LibTactics.v

(** * LibTactics: A Collection of Handy General-Purpose Tactics *)

(* Chapter maintained by Arthur Chargueraud *)

(** This file contains a set of tactics that extends the set of builtin
    tactics provided with the standard distribution of Coq. It intends
    to overcome a number of limitations of the standard set of tactics,
    and thereby to help user to write shorter and more robust scripts.

    Hopefully, Coq tactics will be improved as time goes by, and this
    file should ultimately be useless. In the meanwhile, serious Coq
    users will probably find it very useful.

    The present file contains the implementation and the detailed
    documentation of those tactics. The SF reader need not read this
    file; instead, he/she is encouraged to read the chapter named
    UseTactics.v, which is gentle introduction to the most useful
    tactics from the LibTactic library.
*)

(** The main features offered are:
       - More convenient syntax for naming hypotheses, with tactics for
         introduction and inversion that take as input only the name of
         hypotheses of type [Prop], rather than the name of all variables.
       - Tactics providing true support for manipulating N-ary conjunctions,
         disjunctions and existentials, hidding the fact that the underlying
         implementation is based on binary propositions.
       - Convenient support for automation: tactics followed with the symbol
       "~" or "*" will call automation on the generated subgoals.
       The symbol "~" stands for [auto] and "*" for [intuition eauto].
       These bindings can be customized.
     - Forward-chaining tactics are provided to instantiate lemmas
       either with variable or hypotheses or a mix of both.
     - A more powerful implementation of [apply] is provided (it is based
       on [refine] and thus behaves better with respect to conversion).
     - An improved inversion tactic which substitutes equalities on variables
       generated by the standard inversion mecanism. Moreover, it supports
       the elimination of dependently-typed equalities (requires axiom [K],
       which is a weak form of Proof Irrelevance).
     - Tactics for saving time when writing proofs, with tactics to
       asserts hypotheses or sub-goals, and improved tactics for
       clearing, renaming, and sorting hypotheses. *)

(** External credits:
- thanks to Xavier Leroy for providing the idea of tactic [forward]
- thanks to Georges Gonthier for the implementation trick in [rapply]
*)

Set Implicit Arguments.

Require Import Coq.Lists.List.

Declare Scope ltac_scope.

(* ################################################################# *)
(** * Fixing Stdlib *)

(* Very important to remove hint trans_eq_bool from LibBool,
 otherwise eauto slows down dramatically:
Lemma test : forall b, b = false.
time eauto 7. (* takes over 4 seconds to fail! *) *)

Local Remove Hints Bool.trans_eq_bool : core.

(* ################################################################# *)
(** * Tools for Programming with Ltac *)

(* ================================================================= *)
(** ** Identity Continuation *)

Ltac idcont tt :=
idtac.

(* ================================================================= *)
(** ** Untyped Arguments for Tactics *)

(** Any Coq value can be boxed into the type [Boxer]. This is
  useful to use Coq computations for implementing tactics. *)

Inductive Boxer : Type :=
| boxer : forall (A:Type), A -> Boxer.

(* ================================================================= *)
(** ** Optional Arguments for Tactics  *)

(** [ltac_no_arg] is a constant that can be used to simulate
  optional arguments in tactic definitions.
  Use [mytactic ltac_no_arg] on the tactic invokation,
  and use [match arg with ltac_no_arg => ..] or
  [match type of arg with ltac_No_arg  => ..] to
  test whether an argument was provided. *)

Inductive ltac_No_arg : Set :=
| ltac_no_arg : ltac_No_arg.

(* ================================================================= *)
(** ** Wildcard Arguments for Tactics  *)

(** [ltac_wild] is a constant that can be used to simulate
  wildcard arguments in tactic definitions. Notation is [__]. *)

Inductive ltac_Wild : Set :=
| ltac_wild : ltac_Wild.

Notation "'__'" := ltac_wild : ltac_scope.

(** [ltac_wilds] is another constant that is typically used to
  simulate a sequence of [N] wildcards, with [N] chosen
  appropriately depending on the context. Notation is [___]. *)

Inductive ltac_Wilds : Set :=
| ltac_wilds : ltac_Wilds.

Notation "'___'" := ltac_wilds : ltac_scope.

Open Scope ltac_scope.

(* ================================================================= *)
(** ** Position Markers *)

(** [ltac_Mark] and [ltac_mark] are dummy definitions used as sentinel
  by tactics, to mark a certain position in the context or in the goal. *)

Inductive ltac_Mark : Type :=
| ltac_mark : ltac_Mark.

(** [gen_until_mark] repeats [generalize] on hypotheses from the
  context, starting from the bottom and stopping as soon as reaching
  an hypothesis of type [Mark]. If fails if [Mark] does not
  appear in the context. *)

Ltac gen_until_mark :=
match goal with H: ?T |- _ =>
match T with
| ltac_Mark => clear H
| _ => generalize H; clear H; gen_until_mark
end end.

(** [gen_until_mark_with_processing F] is similar to [gen_until_mark]
  except that it calls [F] on each hypothesis immediately before
  generalizing it. This is useful for processing the hypotheses. *)

Ltac gen_until_mark_with_processing cont :=
match goal with H: ?T |- _ =>
match T with
| ltac_Mark => clear H
| _ => cont H; generalize H; clear H;
       gen_until_mark_with_processing cont
end end.

(** [intro_until_mark] repeats [intro] until reaching an hypothesis of
  type [Mark]. It throws away the hypothesis [Mark].
  It fails if [Mark] does not appear as an hypothesis in the
  goal. *)

Ltac intro_until_mark :=
match goal with
| |- (ltac_Mark -> _) => intros _
| _ => intro; intro_until_mark
end.

(* ================================================================= *)
(** ** List of Arguments for Tactics  *)

(** A datatype of type [list Boxer] is used to manipulate list of
  Coq values in ltac. Notation is [>> v1 v2 ... vN] for building
  a list containing the values [v1] through [vN]. *)
(* Note: could attempt the use of a recursive notation *)

Notation "'>>'" :=
(@nil Boxer)
(at level 0)
: ltac_scope.
Notation "'>>' v1" :=
((boxer v1)::nil)
(at level 0, v1 at level 0)
: ltac_scope.
Notation "'>>' v1 v2" :=
((boxer v1)::(boxer v2)::nil)
(at level 0, v1 at level 0, v2 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3" :=
((boxer v1)::(boxer v2)::(boxer v3)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6 v7" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::(boxer v7)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0, v7 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6 v7 v8" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::(boxer v7)::(boxer v8)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0, v7 at level 0,
 v8 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6 v7 v8 v9" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::(boxer v7)::(boxer v8)::(boxer v9)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0, v7 at level 0,
 v8 at level 0, v9 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6 v7 v8 v9 v10" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::(boxer v7)::(boxer v8)::(boxer v9)::(boxer v10)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0, v7 at level 0,
 v8 at level 0, v9 at level 0, v10 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6 v7 v8 v9 v10 v11" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::(boxer v7)::(boxer v8)::(boxer v9)::(boxer v10)
 ::(boxer v11)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0, v7 at level 0,
 v8 at level 0, v9 at level 0, v10 at level 0, v11 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6 v7 v8 v9 v10 v11 v12" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::(boxer v7)::(boxer v8)::(boxer v9)::(boxer v10)
 ::(boxer v11)::(boxer v12)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0, v7 at level 0,
 v8 at level 0, v9 at level 0, v10 at level 0, v11 at level 0,
 v12 at level 0)
: ltac_scope.
Notation "'>>' v1 v2 v3 v4 v5 v6 v7 v8 v9 v10 v11 v12 v13" :=
((boxer v1)::(boxer v2)::(boxer v3)::(boxer v4)::(boxer v5)
 ::(boxer v6)::(boxer v7)::(boxer v8)::(boxer v9)::(boxer v10)
 ::(boxer v11)::(boxer v12)::(boxer v13)::nil)
(at level 0, v1 at level 0, v2 at level 0, v3 at level 0,
 v4 at level 0, v5 at level 0, v6 at level 0, v7 at level 0,
 v8 at level 0, v9 at level 0, v10 at level 0, v11 at level 0,
 v12 at level 0, v13 at level 0)
: ltac_scope.

(** The tactic [list_boxer_of] inputs a term [E] and returns a term
  of type "list boxer", according to the following rules:
  - if [E] is already of type "list Boxer", then it returns [E];
  - otherwise, it returns the list [(boxer E)::nil]. *)
Ltac list_boxer_of E :=
match type of E with
| List.list Boxer => constr:(E)
| _ => constr:((boxer E)::nil)
end.

(* ================================================================= *)
(** ** Databases of Lemmas  *)

(** Use the hint facility to implement a database mapping
  terms to terms. To declare a new database, use a definition:
  [Definition mydatabase := True.]

  Then, to map [mykey] to [myvalue], write the hint:
  [Hint Extern 1 (Register mydatabase mykey) => Provide myvalue.]

  Finally, to query the value associated with a key, run the
  tactic [ltac_database_get mydatabase mykey]. This will leave
  at the head of the goal the term [myvalue]. It can then be
  named and exploited using [intro]. *)

Inductive Ltac_database_token : Prop := ltac_database_token.

Definition ltac_database (D:Boxer) (T:Boxer) (A:Boxer) := Ltac_database_token.

Notation "'Register' D T" := (ltac_database (boxer D) (boxer T) _)
(at level 69, D at level 0, T at level 0).

Lemma ltac_database_provide : forall (A:Boxer) (D:Boxer) (T:Boxer),
ltac_database D T A.
Proof using. split. Qed.

Ltac Provide T := apply (@ltac_database_provide (boxer T)).

Ltac ltac_database_get D T :=
let A := fresh "TEMP" in evar (A:Boxer);
let H := fresh "TEMP" in
assert (H : ltac_database (boxer D) (boxer T) A);
[ subst A; auto
| subst A; match type of H with ltac_database _ _ (boxer ?L) =>
             generalize L end; clear H ].

(* Note for a possible alternative implementation of the ltac_database_token:
 Inductive Ltac_database : Type :=
   | ltac_database : forall A, A -> Ltac_database.
 Implicit Arguments ltac_database [A].
*)

(* ================================================================= *)
(** ** On-the-Fly Removal of Hypotheses *)

(** In a list of arguments [>> H1 H2 .. HN] passed to a tactic
  such as [lets] or [applys] or [forwards] or [specializes],
  the term [rm], an identity function, can be placed in front
  of the name of an hypothesis to be deleted. *)

Definition rm (A:Type) (X:A) := X.

(** [rm_term E] removes one hypothesis that admits the same
  type as [E]. *)

Ltac rm_term E :=
let T := type of E in
match goal with H: T |- _ => try clear H end.

(** [rm_inside E] calls [rm_term Ei] for any subterm
  of the form [rm Ei] found in E *)

Ltac rm_inside E :=
let go E := rm_inside E in
match E with
| rm ?X => rm_term X
| ?X1 ?X2 =>
   go X1; go X2
| ?X1 ?X2 ?X3 =>
   go X1; go X2; go X3
| ?X1 ?X2 ?X3 ?X4 =>
   go X1; go X2; go X3; go X4
| ?X1 ?X2 ?X3 ?X4 ?X5 =>
   go X1; go X2; go X3; go X4; go X5
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X6 =>
   go X1; go X2; go X3; go X4; go X5; go X6
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X6 ?X7 =>
   go X1; go X2; go X3; go X4; go X5; go X6; go X7
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X6 ?X7 ?X8 =>
   go X1; go X2; go X3; go X4; go X5; go X6; go X7; go X8
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X6 ?X7 ?X8 ?X9 =>
   go X1; go X2; go X3; go X4; go X5; go X6; go X7; go X8; go X9
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X6 ?X7 ?X8 ?X9 ?X10 =>
   go X1; go X2; go X3; go X4; go X5; go X6; go X7; go X8; go X9; go X10
| _ => idtac
end.

(** For faster performance, one may deactivate [rm_inside] by
  replacing the body of this definition with [idtac]. *)

Ltac fast_rm_inside E :=
rm_inside E.

(* ================================================================= *)
(** ** Numbers as Arguments *)

(** When tactic takes a natural number as argument, it may be
  parsed either as a natural number or as a relative number.
  In order for tactics to convert their arguments into natural numbers,
  we provide a conversion tactic.

  Note: the tactic [number_to_nat] is extended in [LibInt] to
  take into account the [Z] type. *)

Require Coq.Numbers.BinNums Coq.ZArith.BinInt.

Definition ltac_int_to_nat (x:BinInt.Z) : nat :=
match x with
| BinInt.Z0 => 0%nat
| BinInt.Zpos p => BinPos.nat_of_P p
| BinInt.Zneg p => 0%nat
end.

Ltac number_to_nat N :=
match type of N with
| nat => constr:(N)
| BinInt.Z => let N' := constr:(ltac_int_to_nat N) in eval compute in N'
end.

(** [ltac_pattern E at K] is the same as [pattern E at K] except that
  [K] is a Coq number (nat or Z) rather than a Ltac integer. Syntax
  [ltac_pattern E as K in H] is also available. *)

Tactic Notation "ltac_pattern" constr(E) "at" constr(K) :=
match number_to_nat K with
| 1 => pattern E at 1
| 2 => pattern E at 2
| 3 => pattern E at 3
| 4 => pattern E at 4
| 5 => pattern E at 5
| 6 => pattern E at 6
| 7 => pattern E at 7
| 8 => pattern E at 8
| _ => fail "ltac_pattern: arity not supported"
end.

Tactic Notation "ltac_pattern" constr(E) "at" constr(K) "in" hyp(H) :=
match number_to_nat K with
| 1 => pattern E at 1 in H
| 2 => pattern E at 2 in H
| 3 => pattern E at 3 in H
| 4 => pattern E at 4 in H
| 5 => pattern E at 5 in H
| 6 => pattern E at 6 in H
| 7 => pattern E at 7 in H
| 8 => pattern E at 8 in H
| _ => fail "ltac_pattern: arity not supported"
end.

(** [ltac_set (x := E) at K] is the same as [set (x := E) at K] except
  that [K] is a Coq number (nat or Z) rather than a Ltac integer. *)

Tactic Notation "ltac_set" "(" ident(X) ":=" constr(E) ")" "at" constr(K) :=
match number_to_nat K with
| 1%nat => set (X := E) at 1
| 2%nat => set (X := E) at 2
| 3%nat => set (X := E) at 3
| 4%nat => set (X := E) at 4
| 5%nat => set (X := E) at 5
| 6%nat => set (X := E) at 6
| 7%nat => set (X := E) at 7
| 8%nat => set (X := E) at 8
| 9%nat => set (X := E) at 9
| 10%nat => set (X := E) at 10
| 11%nat => set (X := E) at 11
| 12%nat => set (X := E) at 12
| 13%nat => set (X := E) at 13
| _ => fail "ltac_set: arity not supported"
end.

(* ================================================================= *)
(** ** Testing Tactics *)

(** [show tac] executes a tactic [tac] that produces a result,
  and then display its result. *)

Tactic Notation "show" tactic(tac) :=
let R := tac in pose R.

(** [dup N] produces [N] copies of the current goal. It is useful
  for building examples on which to illustrate behaviour of tactics.
  [dup] is short for [dup 2]. *)

Lemma dup_lemma : forall P, P -> P -> P.
Proof using. auto. Qed.

Ltac dup_tactic N :=
match number_to_nat N with
| 0 => idtac
| S 0 => idtac
| S ?N' => apply dup_lemma; [ | dup_tactic N' ]
end.

Tactic Notation "dup" constr(N) :=
dup_tactic N.
Tactic Notation "dup" :=
dup 2.

(* ================================================================= *)
(** ** Testing evars and non-evars *)

(** [is_not_evar E] succeeds only if [E] is not an evar;
  it fails otherwise. It thus implements the negation of [is_evar] *)

Ltac is_not_evar E :=
first [ is_evar E; fail 1
      | idtac ].

(** [is_evar_as_bool E] evaluates to [true] if [E] is an evar
  and to [false] otherwise. *)

Ltac is_evar_as_bool E :=
constr:(ltac:(first
  [ is_evar E; exact true
  | exact false ])).

(** [has_no_evar E] succeeds if [E] contains no evars. *)

Ltac has_no_evar E :=
first [ has_evar E; fail 1 | idtac ].

(* ================================================================= *)
(** ** Check No Evar in Goal *)

Ltac check_noevar M :=
first [ has_evar M; fail 2 | idtac ].

Ltac check_noevar_hyp H :=
let T := type of H in check_noevar T.

Ltac check_noevar_goal :=
match goal with |- ?G => check_noevar G end.

(* ================================================================= *)
(** ** Helper Function for Introducing Evars *)

(** [with_evar T (fun M => tac)] creates a new evar that can
  be used in the tactic [tac] under the name [M]. *)

Ltac with_evar_base T cont :=
let x := fresh "TEMP" in evar (x:T); cont x; subst x.

Tactic Notation "with_evar" constr(T) tactic(cont) :=
with_evar_base T cont.

(* ================================================================= *)
(** ** Tagging of Hypotheses *)

(** [get_last_hyp tt] is a function that returns the last hypothesis
  at the bottom of the context. It is useful to obtain the default
  name associated with the hypothesis, e.g.
  [intro; let H := get_last_hyp tt in let H' := fresh "P" H in ...] *)

Ltac get_last_hyp tt :=
match goal with H: _ |- _ => constr:(H) end.

(* ================================================================= *)
(** ** More Tagging of Hypotheses *)

(** [ltac_tag_subst] is a specific marker for hypotheses
  which is used to tag hypotheses that are equalities to
  be substituted. *)

Definition ltac_tag_subst (A:Type) (x:A) := x.

(** [ltac_to_generalize] is a specific marker for hypotheses
  to be generalized. *)

Definition ltac_to_generalize (A:Type) (x:A) := x.

Ltac gen_to_generalize :=
repeat match goal with
  H: ltac_to_generalize _ |- _ => generalize H; clear H end.

Ltac mark_to_generalize H :=
let T := type of H in
change T with (ltac_to_generalize T) in H.

(* ================================================================= *)
(** ** Deconstructing Terms *)

(** [get_head E] is a tactic that returns the head constant of the
  term [E], ie, when applied to a term of the form [P x1 ... xN]
  it returns [P]. If [E] is not an application, it returns [E].
  Warning: the tactic seems to loop in some cases when the goal is
  a product and one uses the result of this function. *)

Ltac get_head E :=
match E with
| ?E' ?x => get_head E'
| _ => constr:(E)
end.

(** [get_fun_arg E] is a tactic that decomposes an application
term [E], ie, when applied to a term of the form [X1 ... XN]
it returns a pair made of [X1 .. X(N-1)] and [XN]. *)

Ltac get_fun_arg E :=
match E with
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X6 ?X7 ?X => constr:((X1 X2 X3 X4 X5 X6 X7,X))
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X6 ?X => constr:((X1 X2 X3 X4 X5 X6,X))
| ?X1 ?X2 ?X3 ?X4 ?X5 ?X => constr:((X1 X2 X3 X4 X5,X))
| ?X1 ?X2 ?X3 ?X4 ?X => constr:((X1 X2 X3 X4,X))
| ?X1 ?X2 ?X3 ?X => constr:((X1 X2 X3,X))
| ?X1 ?X2 ?X => constr:((X1 X2,X))
| ?X1 ?X => constr:((X1,X))
end.

(* ================================================================= *)
(** ** Action at Occurence and Action Not at Occurence *)

(** [ltac_action_at K of E do Tac] isolates the [K]-th occurence of [E] in the
  goal, setting it in the form [P E] for some named pattern [P],
  then calls tactic [Tac], and finally unfolds [P]. Syntax
  [ltac_action_at K of E in H do Tac] is also available. *)

Tactic Notation "ltac_action_at" constr(K) "of" constr(E) "do" tactic(Tac) :=
let p := fresh "TEMP" in ltac_pattern E at K;
match goal with |- ?P _ => set (p:=P) end;
Tac; unfold p; clear p.

Tactic Notation "ltac_action_at" constr(K) "of" constr(E) "in" hyp(H) "do" tactic(Tac) :=
let p := fresh "TEMP" in ltac_pattern E at K in H;
match type of H with ?P _ => set (p:=P) in H end;
Tac; unfold p in H; clear p.

(** [protects E do Tac] temporarily assigns a name to the expression [E]
  so that the execution of tactic [Tac] will not modify [E]. This is
  useful for instance to restrict the action of [simpl]. *)

Tactic Notation "protects" constr(E) "do" tactic(Tac) :=
(* let x := fresh "TEMP" in sets_eq x: E; T; subst x. *)
let x := fresh "TEMP" in let H := fresh "TEMP" in
set (X := E) in *; assert (H : X = E) by reflexivity;
clearbody X; Tac; subst x.

Tactic Notation "protects" constr(E) "do" tactic(Tac) "/" :=
protects E do Tac.

(* ================================================================= *)
(** ** An Alias for [eq] *)

(** [eq'] is an alias for [eq] to be used for equalities in
  inductive definitions, so that they don't get mixed with
  equalities generated by [inversion]. *)

Definition eq' := @eq.

Local Hint Unfold eq' : core.

Notation "x '='' y" := (@eq' _ x y)
(at level 70, y at next level).

(* ################################################################# *)
(** * Common Tactics for Simplifying Goals Like [intuition] *)

Ltac jauto_set_hyps :=
repeat match goal with H: ?T |- _ =>
  match T with
  | _ /\ _ => destruct H
  | exists a, _ => destruct H
  | _ => generalize H; clear H
  end
end.

Ltac jauto_set_goal :=
repeat match goal with
| |- exists a, _ => esplit
| |- _ /\ _ => split
end.

Ltac jauto_set :=
intros; jauto_set_hyps;
intros; jauto_set_goal;
unfold not in *.


(* ################################################################# *)
(** * Backward and Forward Chaining *)

(* ================================================================= *)
(** ** Application *)

Ltac old_refine f :=
refine f. (* ; shelve_unifiable. *)

(** [rapply] is a tactic similar to [eapply] except that it is
  based on the [refine] tactics, and thus is strictly more
  powerful (at least in theory :). In short, it is able to perform
  on-the-fly conversions when required for arguments to match,
  and it is able to instantiate existentials when required. *)

Tactic Notation "rapply" constr(t) :=
first  (* --Note: the @ are not useful *)
[ eexact (@t)
| old_refine (@t)
| old_refine (@t _)
| old_refine (@t _ _)
| old_refine (@t _ _ _)
| old_refine (@t _ _ _ _)
| old_refine (@t _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _ _ _ _ _ _ _)
| old_refine (@t _ _ _ _ _ _ _ _ _ _ _ _ _ _ _)
].

(** No-typeclass refine apply, TEMPORARY for Coq < 8.11. *)

Ltac nrapply H :=
first
[ notypeclasses refine (H)
| notypeclasses refine (H _)
| notypeclasses refine (H _ _)
| notypeclasses refine (H _ _ _)
| notypeclasses refine (H _ _ _ _)
| notypeclasses refine (H _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _ _ _ _ _ _ _)
| notypeclasses refine (H _ _ _ _ _ _ _ _ _ _ _ _ _ _) ].

(** The tactics [applys_N T], where [N] is a natural number,
  provides a more efficient way of using [applys T]. It avoids
  trying out all possible arities, by specifying explicitely
  the arity of function [T]. *)

Tactic Notation "rapply_0" constr(t) :=
old_refine (@t).
Tactic Notation "rapply_1" constr(t) :=
old_refine (@t _).
Tactic Notation "rapply_2" constr(t) :=
old_refine (@t _ _).
Tactic Notation "rapply_3" constr(t) :=
old_refine (@t _ _ _).
Tactic Notation "rapply_4" constr(t) :=
old_refine (@t _ _ _ _).
Tactic Notation "rapply_5" constr(t) :=
old_refine (@t _ _ _ _ _).
Tactic Notation "rapply_6" constr(t) :=
old_refine (@t _ _ _ _ _ _).
Tactic Notation "rapply_7" constr(t) :=
old_refine (@t _ _ _ _ _ _ _).
Tactic Notation "rapply_8" constr(t) :=
old_refine (@t _ _ _ _ _ _ _ _).
Tactic Notation "rapply_9" constr(t) :=
old_refine (@t _ _ _ _ _ _ _ _ _).
Tactic Notation "rapply_10" constr(t) :=
old_refine (@t _ _ _ _ _ _ _ _ _ _).

(** [lets_base H E] adds an hypothesis [H : T] to the context, where [T] is
  the type of term [E]. If [H] is an introduction pattern, it will
  destruct [H] according to the pattern. *)

Ltac lets_base I E := generalize E; intros I.

(** [applys_to H E] transform the type of hypothesis [H] by
  replacing it by the result of the application of the term
  [E] to [H]. Intuitively, it is equivalent to [lets H: (E H)]. *)

Tactic Notation "applys_to" hyp(H) constr(E) :=
let H' := fresh "TEMP" in rename H into H';
(first [ lets_base H (E H')
       | lets_base H (E _ H')
       | lets_base H (E _ _ H')
       | lets_base H (E _ _ _ H')
       | lets_base H (E _ _ _ _ H')
       | lets_base H (E _ _ _ _ _ H')
       | lets_base H (E _ _ _ _ _ _ H')
       | lets_base H (E _ _ _ _ _ _ _ H')
       | lets_base H (E _ _ _ _ _ _ _ _ H')
       | lets_base H (E _ _ _ _ _ _ _ _ _ H') ]
); clear H'.

(** [applys_to H1,...,HN E] applys [E] to several hypotheses *)

Tactic Notation "applys_to" hyp(H1) "," hyp(H2) constr(E) :=
applys_to H1 E; applys_to H2 E.
Tactic Notation "applys_to" hyp(H1) "," hyp(H2) "," hyp(H3) constr(E) :=
applys_to H1 E; applys_to H2 E; applys_to H3 E.
Tactic Notation "applys_to" hyp(H1) "," hyp(H2) "," hyp(H3) "," hyp(H4) constr(E) :=
applys_to H1 E; applys_to H2 E; applys_to H3 E; applys_to H4 E.

(** [constructors] calls [constructor] or [econstructor]. *)

Tactic Notation "constructors" :=
first [ constructor | econstructor ]; unfold eq'.

(* ================================================================= *)
(** ** Assertions *)

(** [asserts H: T] is another syntax for [assert (H : T)], which
  also works with introduction patterns. For instance, one can write:
  [asserts [x P] (exists n, n = 3)], or
  [asserts [H|H] (n = 0 \/ n = 1)]. *)

Tactic Notation "asserts" simple_intropattern(I) ":" constr(T) :=
let H := fresh "TEMP" in assert (H : T);
[ | generalize H; clear H; intros I ].

(** [asserts H1 .. HN: T] is a shorthand for
  [asserts [H1 [H2 [.. HN]]]: T]. *)

Tactic Notation "asserts" simple_intropattern(I1)
simple_intropattern(I2) ":" constr(T) :=
asserts [I1 I2]: T.
Tactic Notation "asserts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) ":" constr(T) :=
asserts [I1 [I2 I3]]: T.
Tactic Notation "asserts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3)
simple_intropattern(I4) ":" constr(T) :=
asserts [I1 [I2 [I3 I4]]]: T.
Tactic Notation "asserts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3)
simple_intropattern(I4) simple_intropattern(I5) ":" constr(T) :=
asserts [I1 [I2 [I3 [I4 I5]]]]: T.
Tactic Notation "asserts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3)
simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) ":" constr(T) :=
asserts [I1 [I2 [I3 [I4 [I5 I6]]]]]: T.

(** [asserts: T] is [asserts H: T] with [H] being chosen automatically. *)

Tactic Notation "asserts" ":" constr(T) :=
let H := fresh "TEMP" in asserts H : T.

(** [cuts H: T] is the same as [asserts H: T] except that the two subgoals
  generated are swapped: the subgoal [T] comes second. Note that contrary
  to [cut], it introduces the hypothesis. *)

Tactic Notation "cuts" simple_intropattern(I) ":" constr(T) :=
cut (T); [ intros I | idtac ].

(** [cuts: T] is [cuts H: T] with [H] being chosen automatically. *)

Tactic Notation "cuts" ":" constr(T) :=
let H := fresh "TEMP" in cuts H: T.

(** [cuts H1 .. HN: T] is a shorthand for
  [cuts \[H1 \[H2 \[.. HN\]\]\]\]: T]. *)

Tactic Notation "cuts" simple_intropattern(I1)
simple_intropattern(I2) ":" constr(T) :=
cuts [I1 I2]: T.
Tactic Notation "cuts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) ":" constr(T) :=
cuts [I1 [I2 I3]]: T.
Tactic Notation "cuts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3)
simple_intropattern(I4) ":" constr(T) :=
cuts [I1 [I2 [I3 I4]]]: T.
Tactic Notation "cuts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3)
simple_intropattern(I4) simple_intropattern(I5) ":" constr(T) :=
cuts [I1 [I2 [I3 [I4 I5]]]]: T.
Tactic Notation "cuts" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3)
simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) ":" constr(T) :=
cuts [I1 [I2 [I3 [I4 [I5 I6]]]]]: T.

(* ================================================================= *)
(** ** Instantiation and Forward-Chaining *)

(** The instantiation tactics are used to instantiate a lemma [E]
  (whose type is a product) on some arguments. The type of [E] is
  made of implications and universal quantifications, e.g.
  [forall x, P x -> forall y z, Q x y z -> R z].

  The first possibility is to provide arguments in order: first [x],
  then a proof of [P x], then [y] etc... In this mode, called "Args",
  all the arguments are to be provided. If a wildcard is provided
  (written [__]), then an existential variable will be introduced in
  place of the argument.

  It is very convenient to give some arguments the lemma should be
  instantiated on, and let the tactic find out automatically where
  underscores should be insterted. Underscore arguments [__] are
  interpret as follows: an underscore means that we want to skip the
  argument that has the same type as the next real argument provided
  (real means not an underscore). If there is no real argument after
  underscore, then the underscore is used for the first possible argument.

  The general syntax is [tactic (>> E1 .. EN)] where [tactic] is
  the name of the tactic (possibly with some arguments) and [Ei]
  are the arguments. Moreover, some tactics accept the syntax
  [tactic E1 .. EN] as short for [tactic (>> E1 .. EN)] for
  values of [N] up to 5.

  Finally, if the argument [EN] given is a triple-underscore [___],
  then it is equivalent to providing a list of wildcards, with
  the appropriate number of wildcards. This means that all
  the remaining arguments of the lemma will be instantiated.
  Definitions in the conclusion are not unfolded in this case. *)

(* Underlying implementation *)

Ltac app_assert t P cont :=
let H := fresh "TEMP" in
assert (H : P); [ | cont(t H); clear H ].

Ltac app_evar t A cont :=
let x := fresh "TEMP" in
evar (x:A);
let t' := constr:(t x) in
let t'' := (eval unfold x in t') in
subst x; cont t''.

Ltac app_arg t P v cont :=
let H := fresh "TEMP" in
assert (H : P); [ apply v | cont(t H); try clear H ].

Ltac build_app_alls t final :=
let rec go t :=
  match type of t with
  | ?P -> ?Q => app_assert t P go
  | forall _:?A, _ => app_evar t A go
  | _ => final t
  end in
go t.

Ltac boxerlist_next_type vs :=
match vs with
| nil => constr:(ltac_wild)
| (boxer ltac_wild)::?vs' => boxerlist_next_type vs'
| (boxer ltac_wilds)::_ => constr:(ltac_wild)
| (@boxer ?T _)::_ => constr:(T)
end.

(* Note: refuse to instantiate a dependent hypothesis with a proposition;
  refuse to instantiate an argument of type Type with one that
  does not have the type Type.
*)

Ltac build_app_hnts t vs final :=
let rec go t vs :=
  match vs with
  | nil => first [ final t | fail 1 ]
  | (boxer ltac_wilds)::_ => first [ build_app_alls t final | fail 1 ]
  | (boxer ?v)::?vs' =>
    let cont t' := go t' vs in
    let cont' t' := go t' vs' in
    let T := type of t in
    let T := eval hnf in T in
    match v with
    | ltac_wild =>
       first [ let U := boxerlist_next_type vs' in
         match U with
         | ltac_wild =>
           match T with
           | ?P -> ?Q => first [ app_assert t P cont' | fail 3 ]
           | forall _:?A, _ => first [ app_evar t A cont' | fail 3 ]
           end
         | _ =>
           match T with  (* should test T for unifiability *)
           | U -> ?Q => first [ app_assert t U cont' | fail 3 ]
           | forall _:U, _ => first [ app_evar t U cont' | fail 3 ]
           | ?P -> ?Q => first [ app_assert t P cont | fail 3 ]
           | forall _:?A, _ => first [ app_evar t A cont | fail 3 ]
           end
         end
       | fail 2 ]
    | _ =>
        match T with
        | ?P -> ?Q => first [ app_arg t P v cont'
                            | app_assert t P cont
                            | fail 3 ]
         | forall _:Type, _ =>
            match type of v with
            | Type => first [ cont' (t v)
                            | app_evar t Type cont
                            | fail 3 ]
            | _ => first [ app_evar t Type cont
                         | fail 3 ]
            end
        | forall _:?A, _ =>
           let V := type of v in
           match type of V with
           | Prop =>  first [ app_evar t A cont
                            | fail 3 ]
           | _ => first [ cont' (t v)
                        | app_evar t A cont
                        | fail 3 ]
           end
        end
    end
  end in
go t vs.

(** newer version : support for typeclasses *)

Ltac app_typeclass t cont :=
let t' := constr:(t _) in
cont t'.

Ltac build_app_alls t final ::=
let rec go t :=
  match type of t with
  | ?P -> ?Q => app_assert t P go
  | forall _:?A, _ =>
      first [ app_evar t A go
            | app_typeclass t go
            | fail 3 ]
  | _ => final t
  end in
go t.

Ltac build_app_hnts t vs final ::=
let rec go t vs :=
  match vs with
  | nil => first [ final t | fail 1 ]
  | (boxer ltac_wilds)::_ => first [ build_app_alls t final | fail 1 ]
  | (boxer ?v)::?vs' =>
    let cont t' := go t' vs in
    let cont' t' := go t' vs' in
    let T := type of t in
    let T := eval hnf in T in
    match v with
    | ltac_wild =>
       first [ let U := boxerlist_next_type vs' in
         match U with
         | ltac_wild =>
           match T with
           | ?P -> ?Q => first [ app_assert t P cont' | fail 3 ]
           | forall _:?A, _ => first [ app_typeclass t cont'
                                     | app_evar t A cont'
                                     | fail 3 ]
           end
         | _ =>
           match T with  (* should test T for unifiability *)
           | U -> ?Q => first [ app_assert t U cont' | fail 3 ]
           | forall _:U, _ => first
               [ app_typeclass t cont'
               | app_evar t U cont'
               | fail 3 ]
           | ?P -> ?Q => first [ app_assert t P cont | fail 3 ]
           | forall _:?A, _ => first
               [ app_typeclass t cont
               | app_evar t A cont
               | fail 3 ]
           end
         end
       | fail 2 ]
    | _ =>
        match T with
        | ?P -> ?Q => first [ app_arg t P v cont'
                            | app_assert t P cont
                            | fail 3 ]
         | forall _:Type, _ =>
            match type of v with
            | Type => first [ cont' (t v)
                            | app_evar t Type cont
                            | fail 3 ]
            | _ => first [ app_evar t Type cont
                         | fail 3 ]
            end
        | forall _:?A, _ =>
           let V := type of v in
           match type of V with
           | Prop => first [ app_typeclass t cont
                            | app_evar t A cont
                            | fail 3 ]
           | _ => first [ cont' (t v)
                        | app_typeclass t cont
                        | app_evar t A cont
                        | fail 3 ]
           end
        end
    end
  end in
go t vs.
(* --Note: use local function for first [...] *)

Ltac build_app args final :=
first [
  match args with (@boxer ?T ?t)::?vs =>
    let t := constr:(t:T) in
    build_app_hnts t vs final;
    fast_rm_inside args
  end
| fail 1 "Instantiation fails for:" args].

Ltac unfold_head_until_product T :=
eval hnf in T.

Ltac args_unfold_head_if_not_product args :=
match args with (@boxer ?T ?t)::?vs =>
  let T' := unfold_head_until_product T in
  constr:((@boxer T' t)::vs)
end.

Ltac args_unfold_head_if_not_product_but_params args :=
match args with
| (boxer ?t)::(boxer ?v)::?vs =>
   args_unfold_head_if_not_product args
| _ => constr:(args)
end.

(** [lets H: (>> E0 E1 .. EN)] will instantiate lemma [E0]
  on the arguments [Ei] (which may be wildcards [__]),
  and name [H] the resulting term. [H] may be an introduction
  pattern, or a sequence of introduction patterns [I1 I2 IN],
  or empty.
  Syntax [lets H: E0 E1 .. EN] is also available. If the last
  argument [EN] is [___] (triple-underscore), then all
  arguments of [H] will be instantiated. *)

Ltac lets_build I Ei :=
let args := list_boxer_of Ei in
let args := args_unfold_head_if_not_product_but_params args in
(*    let Ei''' := args_unfold_head_if_not_product Ei'' in*)
build_app args ltac:(fun R => lets_base I R).

Tactic Notation "lets" simple_intropattern(I) ":" constr(E) :=
lets_build I E.
Tactic Notation "lets" ":" constr(E) :=
let H := fresh in lets H: E.
Tactic Notation "lets" ":" constr(E0)
constr(A1) :=
lets: (>> E0 A1).
Tactic Notation "lets" ":" constr(E0)
constr(A1) constr(A2) :=
lets: (>> E0 A1 A2).
Tactic Notation "lets" ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
lets: (>> E0 A1 A2 A3).
Tactic Notation "lets" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
lets: (>> E0 A1 A2 A3 A4).
Tactic Notation "lets" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
lets: (>> E0 A1 A2 A3 A4 A5).

(* DEPRECATED syntax [lets I1 I2] *)
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2)
":" constr(E) :=
lets [I1 I2]: E.
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) ":" constr(E) :=
lets [I1 [I2 I3]]: E.
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) ":" constr(E) :=
lets [I1 [I2 [I3 I4]]]: E.
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
":" constr(E) :=
lets [I1 [I2 [I3 [I4 I5]]]]: E.

Tactic Notation "lets" simple_intropattern(I) ":" constr(E0)
constr(A1) :=
lets I: (>> E0 A1).
Tactic Notation "lets" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) :=
lets I: (>> E0 A1 A2).
Tactic Notation "lets" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
lets I: (>> E0 A1 A2 A3).
Tactic Notation "lets" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
lets I: (>> E0 A1 A2 A3 A4).
Tactic Notation "lets" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
lets I: (>> E0 A1 A2 A3 A4 A5).

Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2) ":" constr(E0)
constr(A1) :=
lets [I1 I2]: E0 A1.
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2) ":" constr(E0)
constr(A1) constr(A2) :=
lets [I1 I2]: E0 A1 A2.
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2) ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
lets [I1 I2]: E0 A1 A2 A3.
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
lets [I1 I2]: E0 A1 A2 A3 A4.
Tactic Notation "lets" simple_intropattern(I1) simple_intropattern(I2) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
lets [I1 I2]: E0 A1 A2 A3 A4 A5.

(** [forwards H: (>> E0 E1 .. EN)] is short for
  [forwards H: (>> E0 E1 .. EN ___)].
  The arguments [Ei] can be wildcards [__] (except [E0]).
  [H] may be an introduction pattern, or a sequence of
  introduction pattern, or empty.
  Syntax [forwards H: E0 E1 .. EN] is also available. *)

Ltac forwards_build_app_arg Ei :=
let args := list_boxer_of Ei in
let args := (eval simpl in (args ++ ((boxer ___)::nil))) in
let args := args_unfold_head_if_not_product args in
args.

Ltac forwards_then Ei cont :=
let args := forwards_build_app_arg Ei in
let args := args_unfold_head_if_not_product_but_params args in
build_app args cont.

Tactic Notation "forwards" simple_intropattern(I) ":" constr(Ei) :=
let args := forwards_build_app_arg Ei in
lets I: args.

Tactic Notation "forwards" ":" constr(E) :=
let H := fresh in forwards H: E.
Tactic Notation "forwards" ":" constr(E0)
constr(A1) :=
forwards: (>> E0 A1).
Tactic Notation "forwards" ":" constr(E0)
constr(A1) constr(A2) :=
forwards: (>> E0 A1 A2).
Tactic Notation "forwards" ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
forwards: (>> E0 A1 A2 A3).
Tactic Notation "forwards" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
forwards: (>> E0 A1 A2 A3 A4).
Tactic Notation "forwards" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
forwards: (>> E0 A1 A2 A3 A4 A5).

(* --DEPRECATED syntax *)
Tactic Notation "forwards" simple_intropattern(I1) simple_intropattern(I2)
":" constr(E) :=
forwards [I1 I2]: E.
Tactic Notation "forwards" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) ":" constr(E) :=
forwards [I1 [I2 I3]]: E.
Tactic Notation "forwards" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) ":" constr(E) :=
forwards [I1 [I2 [I3 I4]]]: E.
Tactic Notation "forwards" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
":" constr(E) :=
forwards [I1 [I2 [I3 [I4 I5]]]]: E.

Tactic Notation "forwards" simple_intropattern(I) ":" constr(E0)
constr(A1) :=
forwards I: (>> E0 A1).
Tactic Notation "forwards" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) :=
forwards I: (>> E0 A1 A2).
Tactic Notation "forwards" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
forwards I: (>> E0 A1 A2 A3).
Tactic Notation "forwards" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
forwards I: (>> E0 A1 A2 A3 A4).
Tactic Notation "forwards" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
forwards I: (>> E0 A1 A2 A3 A4 A5).

(** [forwards_nounfold I: E] is like [forwards I: E] but does not
  unfold the head constant of [E] if there is no visible quantification
  or hypothesis in [E]. It is meant to be used mainly by tactics. *)

Tactic Notation "forwards_nounfold" simple_intropattern(I) ":" constr(Ei) :=
let args := list_boxer_of Ei in
let args := (eval simpl in (args ++ ((boxer ___)::nil))) in
build_app args ltac:(fun R => lets_base I R).

(** [forwards_nounfold_then E ltac:(fun K => ..)]
  is like [forwards: E] but it provides the resulting term
  to a continuation, under the name [K]. *)

Ltac forwards_nounfold_then Ei cont :=
let args := list_boxer_of Ei in
let args := (eval simpl in (args ++ ((boxer ___)::nil))) in
build_app args cont.

(** [applys (>> E0 E1 .. EN)] instantiates lemma [E0]
  on the arguments [Ei] (which may be wildcards [__]),
  and apply the resulting term to the current goal,
  using the tactic [applys] defined earlier on.
  [applys E0 E1 E2 .. EN] is also available. *)

Ltac applys_build Ei :=
let args := list_boxer_of Ei in
let args := args_unfold_head_if_not_product_but_params args in
build_app args ltac:(fun R =>
 first [ apply R | eapply R | rapply R ]).

Ltac applys_base E :=
match type of E with
| list Boxer => applys_build E
| _ => first [ rapply E | applys_build E ]
end; fast_rm_inside E.

Tactic Notation "applys" constr(E) :=
applys_base E.
Tactic Notation "applys" constr(E0) constr(A1) :=
applys (>> E0 A1).
Tactic Notation "applys" constr(E0) constr(A1) constr(A2) :=
applys (>> E0 A1 A2).
Tactic Notation "applys" constr(E0) constr(A1) constr(A2) constr(A3) :=
applys (>> E0 A1 A2 A3).
Tactic Notation "applys" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) :=
applys (>> E0 A1 A2 A3 A4).
Tactic Notation "applys" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
applys (>> E0 A1 A2 A3 A4 A5).

(** [fapplys (>> E0 E1 .. EN)] instantiates lemma [E0]
  on the arguments [Ei] and on the argument [___] meaning
  that all evars should be explicitly instantiated,
  and apply the resulting term to the current goal.
  [fapplys E0 E1 E2 .. EN] is also available. *)

Ltac fapplys_build Ei :=
let args := list_boxer_of Ei in
let args := (eval simpl in (args ++ ((boxer ___)::nil))) in
let args := args_unfold_head_if_not_product_but_params args in
build_app args ltac:(fun R => apply R).

Tactic Notation "fapplys" constr(E0) :=
match type of E0 with
| list Boxer => fapplys_build E0
| _ => fapplys_build (>> E0)
end.
Tactic Notation "fapplys" constr(E0) constr(A1) :=
fapplys (>> E0 A1).
Tactic Notation "fapplys" constr(E0) constr(A1) constr(A2) :=
fapplys (>> E0 A1 A2).
Tactic Notation "fapplys" constr(E0) constr(A1) constr(A2) constr(A3) :=
fapplys (>> E0 A1 A2 A3).
Tactic Notation "fapplys" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) :=
fapplys (>> E0 A1 A2 A3 A4).
Tactic Notation "fapplys" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
fapplys (>> E0 A1 A2 A3 A4 A5).

(** [specializes H (>> E1 E2 .. EN)] will instantiate hypothesis [H]
  on the arguments [Ei] (which may be wildcards [__]). If the last
  argument [EN] is [___] (triple-underscore), then all arguments of
  [H] get instantiated. *)

Ltac specializes_build H Ei :=
let H' := fresh "TEMP" in rename H into H';
let args := list_boxer_of Ei in
let args := constr:((boxer H')::args) in
let args := args_unfold_head_if_not_product args in
build_app args ltac:(fun R => lets H: R);
clear H'.

Ltac specializes_base H Ei :=
specializes_build H Ei; fast_rm_inside Ei.

Tactic Notation "specializes" hyp(H) :=
specializes_base H (___).
Tactic Notation "specializes" hyp(H) constr(A) :=
specializes_base H A.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) :=
specializes H (>> A1 A2).
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) :=
specializes H (>> A1 A2 A3).
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) constr(A4) :=
specializes H (>> A1 A2 A3 A4).
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
specializes H (>> A1 A2 A3 A4 A5).

(** [specializes_vars H] is equivalent to [specializes H __ .. __]
  with as many double underscore as the number of dependent arguments
  visible from the type of [H]. Note that no unfolding is currently
  being performed (this behavior might change in the future).
  The current implementation is restricted to the case where
  [H] is an existing hypothesis -- Note: this could be generalized. *)

Ltac specializes_var_base H :=
match type of H with
| ?P -> ?Q => fail 1
| forall _:_, _ => specializes H __
end.

Ltac specializes_vars_base H :=
repeat (specializes_var_base H).

Tactic Notation "specializes_var" hyp(H) :=
specializes_var_base H.

Tactic Notation "specializes_vars" hyp(H) :=
specializes_vars_base H.

(* ================================================================= *)
(** ** Experimental Tactics for Application *)

(** [fapply] is a version of [apply] based on [forwards]. *)

Tactic Notation "fapply" constr(E) :=
let H := fresh "TEMP" in forwards H: E;
first [ apply H | eapply H | rapply H | hnf; apply H
      | hnf; eapply H | applys H ].
 (* Note: is applys redundant with rapply ? *)

(** [sapply] stands for "super apply". It tries
  [apply], [eapply], [applys] and [fapply],
  and also tries to head-normalize the goal first. *)

Tactic Notation "sapply" constr(H) :=
first [ apply H | eapply H | rapply H | applys H
      | hnf; apply H | hnf; eapply H | hnf; applys H
      | fapply H ].

(* ================================================================= *)
(** ** Adding Assumptions *)

(** [lets_simpl H: E] is the same as [lets H: E] excepts that it
  calls [simpl] on the hypothesis H.
  [lets_simpl: E] is also provided. *)

Tactic Notation "lets_simpl" ident(H) ":" constr(E) :=
lets H: E; try simpl in H.

Tactic Notation "lets_simpl" ":" constr(T) :=
let H := fresh "TEMP" in lets_simpl H: T.

(** [lets_hnf H: E] is the same as [lets H: E] excepts that it
  calls [hnf] to set the definition in head normal form.
  [lets_hnf: E] is also provided. *)

Tactic Notation "lets_hnf" ident(H) ":" constr(E) :=
lets H: E; hnf in H.

Tactic Notation "lets_hnf" ":" constr(T) :=
let H := fresh "TEMP" in lets_hnf H: T.

(** [puts X: E] is a synonymous for [pose (X := E)].
  Alternative syntax is [puts: E]. *)

Tactic Notation "puts" ident(X) ":" constr(E) :=
pose (X := E).
Tactic Notation "puts" ":" constr(E) :=
let X := fresh "X" in pose (X := E).

(* ================================================================= *)
(** ** Application of Tautologies *)

(** [logic E], where [E] is a fact, is equivalent to
  [assert H:E; [tauto | eapply H; clear H]]. It is useful for instance
  to prove a conjunction [A /\ B] by showing first [A] and then [A -> B],
  through the command [logic (foral A B, A -> (A -> B) -> A /\ B)] *)

Ltac logic_base E cont :=
assert (H:E); [ cont tt | eapply H; clear H ].

Tactic Notation "logic" constr(E) :=
logic_base E ltac:(fun _ => tauto).

(* ================================================================= *)
(** ** Application Modulo Equalities *)

(** The tactic [equates] replaces a goal of the form
  [P x y z] with a goal of the form [P x ?a z] and a
  subgoal [?a = y]. The introduction of the evar [?a] makes
  it possible to apply lemmas that would not apply to the
  original goal, for example a lemma of the form
  [forall n m, P n n m], because [x] and [y] might be equal
  but not convertible.

  Usage is [equates i1 ... ik], where the indices are the
  positions of the arguments to be replaced by evars,
  counting from the right-hand side. If [0] is given as
  argument, then the entire goal is replaced by an evar. *)

Section equatesLemma.
Variables (A0 A1 : Type).
Variables (A2 : forall (x1 : A1), Type).
Variables (A3 : forall (x1 : A1) (x2 : A2 x1), Type).
Variables (A4 : forall (x1 : A1) (x2 : A2 x1) (x3 : A3 x2), Type).
Variables (A5 : forall (x1 : A1) (x2 : A2 x1) (x3 : A3 x2) (x4 : A4 x3), Type).
Variables (A6 : forall (x1 : A1) (x2 : A2 x1) (x3 : A3 x2) (x4 : A4 x3) (x5 : A5 x4), Type).

Lemma equates_0 : forall (P Q:Prop),
P -> P = Q -> Q.
Proof using. intros. subst. auto. Qed.

Lemma equates_1 :
forall (P:A0->Prop) x1 y1,
P y1 -> x1 = y1 -> P x1.
Proof using. intros. subst. auto. Qed.

Lemma equates_2 :
forall y1 (P:A0->forall(x1:A1),Prop) x1 x2,
P y1 x2 -> x1 = y1 -> P x1 x2.
Proof using. intros. subst. auto. Qed.

Lemma equates_3 :
forall y1 (P:A0->forall(x1:A1)(x2:A2 x1),Prop) x1 x2 x3,
P y1 x2 x3 -> x1 = y1 -> P x1 x2 x3.
Proof using. intros. subst. auto. Qed.

Lemma equates_4 :
forall y1 (P:A0->forall(x1:A1)(x2:A2 x1)(x3:A3 x2),Prop) x1 x2 x3 x4,
P y1 x2 x3 x4 -> x1 = y1 -> P x1 x2 x3 x4.
Proof using. intros. subst. auto. Qed.

Lemma equates_5 :
forall y1 (P:A0->forall(x1:A1)(x2:A2 x1)(x3:A3 x2)(x4:A4 x3),Prop) x1 x2 x3 x4 x5,
P y1 x2 x3 x4 x5 -> x1 = y1 -> P x1 x2 x3 x4 x5.
Proof using. intros. subst. auto. Qed.

Lemma equates_6 :
forall y1 (P:A0->forall(x1:A1)(x2:A2 x1)(x3:A3 x2)(x4:A4 x3)(x5:A5 x4),Prop)
x1 x2 x3 x4 x5 x6,
P y1 x2 x3 x4 x5 x6 -> x1 = y1 -> P x1 x2 x3 x4 x5 x6.
Proof using. intros. subst. auto. Qed.

End equatesLemma.

Ltac equates_lemma n :=
match number_to_nat n with
| 0 => constr:(equates_0)
| 1 => constr:(equates_1)
| 2 => constr:(equates_2)
| 3 => constr:(equates_3)
| 4 => constr:(equates_4)
| 5 => constr:(equates_5)
| 6 => constr:(equates_6)
| _ => fail 100 "equates tactic only support up to arity 6"
end.

Ltac equates_one n :=
let L := equates_lemma n in
eapply L.

Ltac equates_several E cont :=
let all_pos := match type of E with
  | List.list Boxer => constr:(E)
  | _ => constr:((boxer E)::nil)
  end in
let rec go pos :=
   match pos with
   | nil => cont tt
   | (boxer ?n)::?pos' => equates_one n; [ instantiate; go pos' | ]
   end in
go all_pos.

Tactic Notation "equates" constr(E) :=
equates_several E ltac:(fun _ => idtac).
Tactic Notation "equates" constr(n1) constr(n2) :=
equates (>> n1 n2).
Tactic Notation "equates" constr(n1) constr(n2) constr(n3) :=
equates (>> n1 n2 n3).
Tactic Notation "equates" constr(n1) constr(n2) constr(n3) constr(n4) :=
equates (>> n1 n2 n3 n4).

(** [applys_eq H i1 .. iK] is the same as
  [equates i1 .. iK] followed by [applys H]
  on the first subgoal.

  DEPRECATED: use [applys_eq H] instead. *)

Tactic Notation "applys_eq" constr(H) constr(E) :=
equates_several E ltac:(fun _ => sapply H).
Tactic Notation "applys_eq" constr(H) constr(n1) constr(n2) :=
applys_eq H (>> n1 n2).
Tactic Notation "applys_eq" constr(H) constr(n1) constr(n2) constr(n3) :=
applys_eq H (>> n1 n2 n3).
Tactic Notation "applys_eq" constr(H) constr(n1) constr(n2) constr(n3) constr(n4) :=
applys_eq H (>> n1 n2 n3 n4).

(** [applys_eq H] helps proving a goal of the form [P x1 .. xN]
  from an hypothesis [H] that concludes [P y1 .. yN], where the
  arguments [xi] and [yi] may or may not be convertible.
  Equalities are produced for all arguments that don't unify.

  The tactic invokes [equates] on all arguments, then calls
  [applys K], and attempts [reflexivity] on the side equalities. *)

Lemma applys_eq_init : forall (P Q:Prop),
P = Q ->
Q ->
P.
Proof using. intros. subst. auto. Qed.

Lemma applys_eq_step_dep : forall B (P Q: (forall A, A->B)) (T:Type),
P = Q ->
P T = Q T.
Proof using. intros. subst. auto. Qed.

Lemma applys_eq_step : forall A B (P Q:A->B) x y,
P = Q ->
x = y ->
P x = Q y.
Proof using. intros. subst. auto. Qed.

Ltac applys_eq_loop tt :=
match goal with
| |- ?P ?x =>
    first [ eapply applys_eq_step; [ applys_eq_loop tt | ]
          | eapply applys_eq_step_dep; applys_eq_loop tt ]
| _ => reflexivity
end.

Ltac applys_eq_core H :=
eapply applys_eq_init;
[ applys_eq_loop tt | applys H ];
try reflexivity.

Tactic Notation "applys_eq" constr(H) :=
applys_eq_core H.

(* ================================================================= *)
(** ** Absurd Goals *)

(** [false_goal] replaces any goal by the goal [False].
  Contrary to the tactic [false] (below), it does not try to do
  anything else *)

Tactic Notation "false_goal" :=
elimtype False.

(** [false_post] is the underlying tactic used to prove goals
  of the form [False]. In the default implementation, it proves
  the goal if the context contains [False] or an hypothesis of the
  form [C x1 .. xN  =  D y1 .. yM], or if the [congruence] tactic
  finds a proof of [x <> x] for some [x]. *)

Ltac false_post :=
solve [ assumption | discriminate | congruence ].

(** [false] replaces any goal by the goal [False], and calls [false_post] *)

Tactic Notation "false" :=
false_goal; try false_post.

(** [tryfalse] tries to solve a goal by contradiction, and leaves
  the goal unchanged if it cannot solve it.
  It is equivalent to [try solve \[ false \]]. *)

Tactic Notation "tryfalse" :=
try solve [ false ].

(** [false E] tries to exploit lemma [E] to prove the goal false.
  [false E1 .. EN] is equivalent to [false (>> E1 .. EN)],
  which tries to apply [applys (>> E1 .. EN)] and if it
  does not work then tries [forwards H: (>> E1 .. EN)]
  followed with [false] *)

Ltac false_then E cont :=
false_goal; first
[ applys E; instantiate
| forwards_then E ltac:(fun M =>
    pose M; jauto_set_hyps; intros; false) ];
cont tt.
(* Note: is [cont] needed? *)

Tactic Notation "false" constr(E) :=
false_then E ltac:(fun _ => idtac).
Tactic Notation "false" constr(E) constr(E1) :=
false (>> E E1).
Tactic Notation "false" constr(E) constr(E1) constr(E2) :=
false (>> E E1 E2).
Tactic Notation "false" constr(E) constr(E1) constr(E2) constr(E3) :=
false (>> E E1 E2 E3).
Tactic Notation "false" constr(E) constr(E1) constr(E2) constr(E3) constr(E4) :=
false (>> E E1 E2 E3 E4).

(** [false_invert H] proves a goal if it absurd after
  calling [inversion H] and [false] *)

Ltac false_invert_for H :=
let M := fresh "TEMP" in pose (M := H); inversion H; false.

Tactic Notation "false_invert" constr(H) :=
try solve [ false_invert_for H | false ].

(** [false_invert] proves any goal provided there is at least
  one hypothesis [H] in the context (or as a universally quantified
  hypothesis visible at the head of the goal) that can be proved absurd by calling
  [inversion H]. *)

Ltac false_invert_iter :=
match goal with H:_ |- _ =>
  solve [ inversion H; false
        | clear H; false_invert_iter
        | fail 2 ] end.

Tactic Notation "false_invert" :=
intros; solve [ false_invert_iter | false ].

(** [tryfalse_invert H] and [tryfalse_invert] are like the
  above but leave the goal unchanged if they don't solve it. *)

Tactic Notation "tryfalse_invert" constr(H) :=
try (false_invert H).

Tactic Notation "tryfalse_invert" :=
try false_invert.

(** [false_neq_self_hyp] proves any goal if the context
  contains an hypothesis of the form [E <> E]. It is
  a restricted and optimized version of [false]. It is
  intended to be used by other tactics only. *)

Ltac false_neq_self_hyp :=
match goal with H: ?x <> ?x |- _ =>
  false_goal; apply H; reflexivity end.


(* ################################################################# *)
(** * Introduction and Generalization *)

(* ================================================================= *)
(** ** Introduction *)

(** [introv] is used to name only non-dependent hypothesis.
- If [introv] is called on a goal of the form [forall x, H],
 it should introduce all the variables quantified with a
 [forall] at the head of the goal, but it does not introduce
 hypotheses that preceed an arrow constructor, like in [P -> Q].
- If [introv] is called on a goal that is not of the form
 [forall x, H] nor [P -> Q], the tactic unfolds definitions
 until the goal takes the form [forall x, H] or [P -> Q].
 If unfolding definitions does not produces a goal of this form,
 then the tactic [introv] does nothing at all. *)

(* [introv_rec] introduces all visible variables.
 It does not try to unfold any definition. *)

Ltac introv_rec :=
match goal with
| |- ?P -> ?Q => idtac
| |- forall _, _ => intro; introv_rec
| |- _ => idtac
end.

(* [introv_noarg] forces the goal to be a [forall] or an [->],
 and then calls [introv_rec] to introduces variables
 (possibly none, in which case [introv] is the same as [hnf]).
 If the goal is not a product, then it does not do anything. *)

Ltac introv_noarg :=
match goal with
| |- ?P -> ?Q => idtac
| |- forall _, _ => introv_rec
| |- ?G => hnf;
   match goal with
   | |- ?P -> ?Q => idtac
   | |- forall _, _ => introv_rec
   end
| |- _ => idtac
end.

(* simpler yet perhaps less efficient imlementation *)
Ltac introv_noarg_not_optimized :=
  intro; match goal with H:_|-_ => revert H end; introv_rec.

(* [introv_arg H] introduces one non-dependent hypothesis
 under the name [H], after introducing the variables
 quantified with a [forall] that preceeds this hypothesis.
 This tactic fails if there does not exist a hypothesis
 to be introduced. *)
(* Note: __ in introv means "intros" *)

Ltac introv_arg H :=
hnf; match goal with
| |- ?P -> ?Q => intros H
| |- forall _, _ => intro; introv_arg H
end.

(* [introv I1 .. IN] iterates [introv Ik] *)

Tactic Notation "introv" :=
introv_noarg.
Tactic Notation "introv" simple_intropattern(I1) :=
introv_arg I1.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2) :=
introv I1; introv I2.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) :=
introv I1; introv I2 I3.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) :=
introv I1; introv I2 I3 I4.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5) :=
introv I1; introv I2 I3 I4 I5.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) :=
introv I1; introv I2 I3 I4 I5 I6.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) :=
introv I1; introv I2 I3 I4 I5 I6 I7.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8) :=
introv I1; introv I2 I3 I4 I5 I6 I7 I8.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8)
simple_intropattern(I9) :=
introv I1; introv I2 I3 I4 I5 I6 I7 I8 I9.
Tactic Notation "introv" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8)
simple_intropattern(I9) simple_intropattern(I10) :=
introv I1; introv I2 I3 I4 I5 I6 I7 I8 I9 I10.

(** [intros_all] repeats [intro] as long as possible. Contrary to [intros],
  it unfolds any definition on the way. Remark that it also unfolds the
  definition of negation, so applying [intros_all] to a goal of the form
  [forall x, P x -> ~Q] will introduce [x] and [P x] and [Q], and will
  leave [False] in the goal. *)

Tactic Notation "intros_all" :=
repeat intro.

(** [intros_hnf] introduces an hypothesis and sets in head normal form *)

Tactic Notation "intro_hnf" :=
intro; match goal with H: _ |- _ => hnf in H end.

(* ================================================================= *)
(** ** Introduction using [=>] and [=>>] *)

(* [=> I1 .. IN] is the same as [intros I1 .. IN] *)

Ltac ltac_intros_post := idtac.

Tactic Notation "=>" :=
intros.
Tactic Notation "=>" simple_intropattern(I1) :=
intros I1.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2) :=
intros I1 I2.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) :=
intros I1 I2 I3.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) :=
intros I1 I2 I3 I4.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5) :=
intros I1 I2 I3 I4 I5.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) :=
intros I1 I2 I3 I4 I5 I6.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) :=
intros I1 I2 I3 I4 I5 I6 I7.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8) :=
intros I1 I2 I3 I4 I5 I6 I7 I8.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8)
simple_intropattern(I9) :=
intros I1 I2 I3 I4 I5 I6 I7 I8 I9.
Tactic Notation "=>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8)
simple_intropattern(I9) simple_intropattern(I10) :=
intros I1 I2 I3 I4 I5 I6 I7 I8 I9 I10.

(* [=>>] first introduces all non-dependent variables,
 then behaves as [intros]. It unfolds the head of the goal using [hnf]
 if there are not head visible quantifiers.

 Remark: instances of [Inhab] are treated as non-dependent and
 are introduced automatically. *)

(* NOTE: this tactic is later redefined for supporting Inhab *)
Ltac intro_nondeps_aux_special_intro G :=
fail.

Ltac intro_nondeps_aux is_already_hnf :=
match goal with
| |- (?P -> ?Q) => idtac
| |- ?G -> _ => intro_nondeps_aux_special_intro G;
                intro; intro_nondeps_aux true
| |- (forall _,_) => intros ?; intro_nondeps_aux true
| |- _ =>
   match is_already_hnf with
   | true => idtac
   | false => hnf; intro_nondeps_aux true
   end
end.

Ltac intro_nondeps tt := intro_nondeps_aux false.

Tactic Notation "=>>" :=
intro_nondeps tt.
Tactic Notation "=>>" simple_intropattern(I1) :=
=>>; intros I1.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2) :=
=>>; intros I1 I2.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) :=
=>>; intros I1 I2 I3.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) :=
=>>; intros I1 I2 I3 I4.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5) :=
=>>; intros I1 I2 I3 I4 I5.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) :=
=>>; intros I1 I2 I3 I4 I5 I6.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) :=
=>>; intros I1 I2 I3 I4 I5 I6 I7.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8) :=
=>>; intros I1 I2 I3 I4 I5 I6 I7 I8.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8)
simple_intropattern(I9) :=
=>>; intros I1 I2 I3 I4 I5 I6 I7 I8 I9.
Tactic Notation "=>>" simple_intropattern(I1) simple_intropattern(I2)
simple_intropattern(I3) simple_intropattern(I4) simple_intropattern(I5)
simple_intropattern(I6) simple_intropattern(I7) simple_intropattern(I8)
simple_intropattern(I9) simple_intropattern(I10) :=
=>>; intros I1 I2 I3 I4 I5 I6 I7 I8 I9 I10.

(* ================================================================= *)
(** ** Generalization *)

(** [gen X1 .. XN] is a shorthand for calling [generalize dependent]
  successively on variables [XN]...[X1]. Note that the variables
  are generalized in reverse order, following the convention of
  the [generalize] tactic: it means that [X1] will be the first
  quantified variable in the resulting goal. *)

Tactic Notation "gen" ident(X1) :=
generalize dependent X1.
Tactic Notation "gen" ident(X1) ident(X2) :=
gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) :=
gen X3; gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) ident(X4)  :=
gen X4; gen X3; gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) ident(X4) ident(X5) :=
gen X5; gen X4; gen X3; gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) ident(X4) ident(X5)
ident(X6) :=
gen X6; gen X5; gen X4; gen X3; gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) ident(X4) ident(X5)
ident(X6) ident(X7) :=
gen X7; gen X6; gen X5; gen X4; gen X3; gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) ident(X4) ident(X5)
ident(X6) ident(X7) ident(X8) :=
gen X8; gen X7; gen X6; gen X5; gen X4; gen X3; gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) ident(X4) ident(X5)
ident(X6) ident(X7) ident(X8) ident(X9) :=
gen X9; gen X8; gen X7; gen X6; gen X5; gen X4; gen X3; gen X2; gen X1.
Tactic Notation "gen" ident(X1) ident(X2) ident(X3) ident(X4) ident(X5)
ident(X6) ident(X7) ident(X8) ident(X9) ident(X10) :=
gen X10; gen X9; gen X8; gen X7; gen X6; gen X5; gen X4; gen X3; gen X2; gen X1.

(** [generalizes X] is a shorthand for calling [generalize X; clear X].
  It is weaker than tactic [gen X] since it does not support
  dependencies. It is mainly intended for writing tactics. *)

Tactic Notation "generalizes" hyp(X) :=
generalize X; clear X.
Tactic Notation "generalizes" hyp(X1) hyp(X2) :=
generalizes X1; generalizes X2.
Tactic Notation "generalizes" hyp(X1) hyp(X2) hyp(X3) :=
generalizes X1 X2; generalizes X3.
Tactic Notation "generalizes" hyp(X1) hyp(X2) hyp(X3) hyp(X4) :=
generalizes X1 X2 X3; generalizes X4.

(* ================================================================= *)
(** ** Naming *)

(** [sets X: E] is the same as [set (X := E) in *], that is,
  it replaces all occurences of [E] by a fresh meta-variable [X]
  whose definition is [E]. *)

Tactic Notation "sets" ident(X) ":" constr(E) :=
set (X := E) in *.

(** [def_to_eq E X H] applies when [X := E] is a local
  definition. It adds an assumption [H: X = E]
  and then clears the definition of [X].
  [def_to_eq_sym] is similar except that it generates
  the equality [H: E = X]. *)

Ltac def_to_eq X HX E :=
assert (HX : X = E) by reflexivity; clearbody X.
Ltac def_to_eq_sym X HX E :=
assert (HX : E = X) by reflexivity; clearbody X.

(** [set_eq X H: E] generates the equality [H: X = E],
  for a fresh name [X], and replaces [E] by [X] in the
  current goal. Syntaxes [set_eq X: E] and
  [set_eq: E] are also available. Similarly,
  [set_eq <- X H: E] generates the equality [H: E = X].

  [sets_eq X HX: E] does the same but replaces [E] by [X]
  everywhere in the goal. [sets_eq X HX: E in H] replaces in [H].
  [set_eq X HX: E in |-] performs no substitution at all. *)

Tactic Notation "set_eq" ident(X) ident(HX) ":" constr(E) :=
set (X := E); def_to_eq X HX E.
Tactic Notation "set_eq" ident(X) ":" constr(E) :=
let HX := fresh "EQ" X in set_eq X HX: E.
Tactic Notation "set_eq" ":" constr(E) :=
let X := fresh "X" in set_eq X: E.

Tactic Notation "set_eq" "<-" ident(X) ident(HX) ":" constr(E) :=
set (X := E); def_to_eq_sym X HX E.
Tactic Notation "set_eq" "<-" ident(X) ":" constr(E) :=
let HX := fresh "EQ" X in set_eq <- X HX: E.
Tactic Notation "set_eq" "<-" ":" constr(E) :=
let X := fresh "X" in set_eq <- X: E.

Tactic Notation "sets_eq" ident(X) ident(HX) ":" constr(E) :=
set (X := E) in *; def_to_eq X HX E.
Tactic Notation "sets_eq" ident(X) ":" constr(E) :=
let HX := fresh "EQ" X in sets_eq X HX: E.
Tactic Notation "sets_eq" ":" constr(E) :=
let X := fresh "X" in sets_eq X: E.

Tactic Notation "sets_eq" "<-" ident(X) ident(HX) ":" constr(E) :=
set (X := E) in *; def_to_eq_sym X HX E.
Tactic Notation "sets_eq" "<-" ident(X) ":" constr(E) :=
let HX := fresh "EQ" X in sets_eq <- X HX: E.
Tactic Notation "sets_eq" "<-" ":" constr(E) :=
let X := fresh "X" in sets_eq <- X: E.

Tactic Notation "set_eq" ident(X) ident(HX) ":" constr(E) "in" hyp(H) :=
set (X := E) in H; def_to_eq X HX E.
Tactic Notation "set_eq" ident(X) ":" constr(E) "in" hyp(H) :=
let HX := fresh "EQ" X in set_eq X HX: E in H.
Tactic Notation "set_eq" ":" constr(E) "in" hyp(H) :=
let X := fresh "X" in set_eq X: E in H.

Tactic Notation "set_eq" "<-" ident(X) ident(HX) ":" constr(E) "in" hyp(H) :=
set (X := E) in H; def_to_eq_sym X HX E.
Tactic Notation "set_eq" "<-" ident(X) ":" constr(E) "in" hyp(H) :=
let HX := fresh "EQ" X in set_eq <- X HX: E in H.
Tactic Notation "set_eq" "<-" ":" constr(E) "in" hyp(H) :=
let X := fresh "X" in set_eq <- X: E in H.

Tactic Notation "set_eq" ident(X) ident(HX) ":" constr(E) "in" "|-" :=
set (X := E) in |-; def_to_eq X HX E.
Tactic Notation "set_eq" ident(X) ":" constr(E) "in" "|-" :=
let HX := fresh "EQ" X in set_eq X HX: E in |-.
Tactic Notation "set_eq" ":" constr(E) "in" "|-" :=
let X := fresh "X" in set_eq X: E in |-.

Tactic Notation "set_eq" "<-" ident(X) ident(HX) ":" constr(E) "in" "|-" :=
set (X := E) in |-; def_to_eq_sym X HX E.
Tactic Notation "set_eq" "<-" ident(X) ":" constr(E) "in" "|-" :=
let HX := fresh "EQ" X in set_eq <- X HX: E in |-.
Tactic Notation "set_eq" "<-" ":" constr(E) "in" "|-" :=
let X := fresh "X" in set_eq <- X: E in |-.

(** [gen_eq X: E] is a tactic whose purpose is to introduce
  equalities so as to work around the limitation of the [induction]
  tactic which typically loses information. [gen_eq E as X] replaces
  all occurences of term [E] with a fresh variable [X] and the equality
  [X = E] as extra hypothesis to the current conclusion. In other words
  a conclusion [C] will be turned into [(X = E) -> C].
  [gen_eq: E] and [gen_eq: E as X] are also accepted. *)

Tactic Notation "gen_eq" ident(X) ":" constr(E) :=
let EQ := fresh "EQ" X in sets_eq X EQ: E; revert EQ.
Tactic Notation "gen_eq" ":" constr(E) :=
let X := fresh "X" in gen_eq X: E.
Tactic Notation "gen_eq" ":" constr(E) "as" ident(X) :=
gen_eq X: E.
Tactic Notation "gen_eq" ident(X1) ":" constr(E1) ","
ident(X2) ":" constr(E2) :=
gen_eq X2: E2; gen_eq X1: E1.
Tactic Notation "gen_eq" ident(X1) ":" constr(E1) ","
ident(X2) ":" constr(E2) "," ident(X3) ":" constr(E3) :=
gen_eq X3: E3; gen_eq X2: E2; gen_eq X1: E1.

(** [sets_let X] finds the first let-expression in the goal
  and names its body [X]. [sets_eq_let X] is similar,
  except that it generates an explicit equality.
  Tactics [sets_let X in H] and [sets_eq_let X in H]
  allow specifying a particular hypothesis (by default,
  the first one that contains a [let] is considered).

  Known limitation: it does not seem possible to support
  naming of multiple let-in constructs inside a term, from ltac. *)

Ltac sets_let_base tac :=
match goal with
| |- context[let _ := ?E in _] => tac E; cbv zeta
| H: context[let _ := ?E in _] |- _ => tac E; cbv zeta in H
end.

Ltac sets_let_in_base H tac :=
match type of H with context[let _ := ?E in _] =>
  tac E; cbv zeta in H end.

Tactic Notation "sets_let" ident(X) :=
sets_let_base ltac:(fun E => sets X: E).
Tactic Notation "sets_let" ident(X) "in" hyp(H) :=
sets_let_in_base H ltac:(fun E => sets X: E).
Tactic Notation "sets_eq_let" ident(X) :=
sets_let_base ltac:(fun E => sets_eq X: E).
Tactic Notation "sets_eq_let" ident(X) "in" hyp(H) :=
sets_let_in_base H ltac:(fun E => sets_eq X: E).

(* ################################################################# *)
(** * Rewriting *)

(** [rewrites E] is similar to [rewrite] except that
  it supports the [rm] directives to clear hypotheses
  on the fly, and that it supports a list of arguments in the form
  [rewrites (>> E1 E2 E3)] to indicate that [forwards] should be
  invoked first before [rewrites] is called. *)

Ltac rewrites_base E cont :=
match type of E with
| List.list Boxer => forwards_then E cont
| _ => cont E; fast_rm_inside E
end.

Tactic Notation "rewrites" constr(E) :=
rewrites_base E ltac:(fun M => rewrite M ).
Tactic Notation "rewrites" constr(E) "in" hyp(H) :=
rewrites_base E ltac:(fun M => rewrite M in H).
Tactic Notation "rewrites" constr(E) "in" "*" :=
rewrites_base E ltac:(fun M => rewrite M in *).
Tactic Notation "rewrites" "<-" constr(E) :=
rewrites_base E ltac:(fun M => rewrite <- M ).
Tactic Notation "rewrites" "<-" constr(E) "in" hyp(H) :=
rewrites_base E ltac:(fun M => rewrite <- M in H).
Tactic Notation "rewrites" "<-" constr(E) "in" "*" :=
rewrites_base E ltac:(fun M => rewrite <- M in *).

(** [erewrites E] is similar to [erewrite] except that
  it supports the [rm] directives to clear hypotheses
  on the fly, and that it supports a list of arguments in the form
  [rewrites (>> E1 E2 E3)] to indicate that [forwards] should be
  invoked first before [rewrites] is called. *)

Tactic Notation "erewrites" constr(E) :=
rewrites_base E ltac:(fun M => erewrite M ).
Tactic Notation "erewrites" constr(E) "in" hyp(H) :=
rewrites_base E ltac:(fun M => erewrite M in H).
Tactic Notation "erewrites" constr(E) "in" "*" :=
rewrites_base E ltac:(fun M => erewrite M in *).
Tactic Notation "erewrites" "<-" constr(E) :=
rewrites_base E ltac:(fun M => erewrite <- M ).
Tactic Notation "erewrites" "<-" constr(E) "in" hyp(H) :=
rewrites_base E ltac:(fun M => erewrite <- M in H).
Tactic Notation "erewrites" "<-" constr(E) "in" "*" :=
rewrites_base E ltac:(fun M => erewrite <- M in *).

(* --Note: should we extend tactics below to use [rewrites]? *)

(** [rewrite_all E] iterates version of [rewrite E] as long as possible.
  Warning: this tactic can easily get into an infinite loop.
  Syntax for rewriting from right to left and/or into an hypothese
  is similar to the one of [rewrite]. *)

Tactic Notation "rewrite_all" constr(E) :=
repeat rewrite E.
Tactic Notation "rewrite_all" "<-" constr(E) :=
repeat rewrite <- E.
Tactic Notation "rewrite_all" constr(E) "in" ident(H) :=
repeat rewrite E in H.
Tactic Notation "rewrite_all" "<-" constr(E) "in" ident(H) :=
repeat rewrite <- E in H.
Tactic Notation "rewrite_all" constr(E) "in" "*" :=
repeat rewrite E in *.
Tactic Notation "rewrite_all" "<-" constr(E) "in" "*" :=
repeat rewrite <- E in *.

(** [asserts_rewrite E] asserts that an equality [E] holds (generating a
  corresponding subgoal) and rewrite it straight away in the current
  goal. It avoids giving a name to the equality and later clearing it.
  Syntax for rewriting from right to left and/or into an hypothese
  is similar to the one of [rewrite]. Note: the tactic [replaces]
  plays a similar role. *)

Ltac asserts_rewrite_tactic E action :=
let EQ := fresh "TEMP" in (assert (EQ : E);
[ idtac | action EQ; clear EQ ]).

Tactic Notation "asserts_rewrite" constr(E) :=
asserts_rewrite_tactic E ltac:(fun EQ => rewrite EQ).
Tactic Notation "asserts_rewrite" "<-" constr(E) :=
asserts_rewrite_tactic E ltac:(fun EQ => rewrite <- EQ).
Tactic Notation "asserts_rewrite" constr(E) "in" hyp(H) :=
asserts_rewrite_tactic E ltac:(fun EQ => rewrite EQ in H).
Tactic Notation "asserts_rewrite" "<-" constr(E) "in" hyp(H) :=
asserts_rewrite_tactic E ltac:(fun EQ => rewrite <- EQ in H).
Tactic Notation "asserts_rewrite" constr(E) "in" "*" :=
asserts_rewrite_tactic E ltac:(fun EQ => rewrite EQ in *).
Tactic Notation "asserts_rewrite" "<-" constr(E) "in" "*" :=
asserts_rewrite_tactic E ltac:(fun EQ => rewrite <- EQ in *).

(** [cuts_rewrite E] is the same as [asserts_rewrite E] except
  that subgoals are permuted. *)

Ltac cuts_rewrite_tactic E action :=
let EQ := fresh "TEMP" in (cuts EQ: E;
[ action EQ; clear EQ | idtac ]).

Tactic Notation "cuts_rewrite" constr(E) :=
cuts_rewrite_tactic E ltac:(fun EQ => rewrite EQ).
Tactic Notation "cuts_rewrite" "<-" constr(E) :=
cuts_rewrite_tactic E ltac:(fun EQ => rewrite <- EQ).
Tactic Notation "cuts_rewrite" constr(E) "in" hyp(H) :=
cuts_rewrite_tactic E ltac:(fun EQ => rewrite EQ in H).
Tactic Notation "cuts_rewrite" "<-" constr(E) "in" hyp(H) :=
cuts_rewrite_tactic E ltac:(fun EQ => rewrite <- EQ in H).

(** [rewrite_except H EQ] rewrites equality [EQ] everywhere
  but in hypothesis [H]. Mainly useful for other tactics. *)

Ltac rewrite_except H EQ :=
let K := fresh "TEMP" in let T := type of H in
set (K := T) in H;
rewrite EQ in *; unfold K in H; clear K.

(** [rewrites E at K] applies when [E] is of the form [T1 = T2]
  rewrites the equality [E] at the [K]-th occurence of [T1]
  in the current goal.
  Syntaxes [rewrites <- E at K] and [rewrites E at K in H]
  are also available. *)

Tactic Notation "rewrites" constr(E) "at" constr(K) :=
match type of E with ?T1 = ?T2 =>
  ltac_action_at K of T1 do (rewrites E) end.
Tactic Notation "rewrites" "<-" constr(E) "at" constr(K) :=
match type of E with ?T1 = ?T2 =>
  ltac_action_at K of T2 do (rewrites <- E) end.
Tactic Notation "rewrites" constr(E) "at" constr(K) "in" hyp(H) :=
match type of E with ?T1 = ?T2 =>
  ltac_action_at K of T1 in H do (rewrites E in H) end.
Tactic Notation "rewrites" "<-" constr(E) "at" constr(K) "in" hyp(H) :=
match type of E with ?T1 = ?T2 =>
  ltac_action_at K of T2 in H do (rewrites <- E in H) end.

(**  ** Replace *)

(** [replaces E with F] is the same as [replace E with F] except that
  the equality [E = F] is generated as first subgoal. Syntax
  [replaces E with F in H] is also available. Note that contrary to
  [replace], [replaces] does not try to solve the equality
  by [assumption]. Note: [replaces E with F] is similar to
  [asserts_rewrite (E = F)]. *)

Tactic Notation "replaces" constr(E) "with" constr(F) :=
let T := fresh "TEMP" in assert (T: E = F); [ | replace E with F; clear T ].

Tactic Notation "replaces" constr(E) "with" constr(F) "in" hyp(H) :=
let T := fresh "TEMP" in assert (T: E = F); [ | replace E with F in H; clear T ].

(** [replaces E at K with F] replaces the [K]-th occurence of [E]
  with [F] in the current goal. Syntax [replaces E at K with F in H]
  is also available. *)

Tactic Notation "replaces" constr(E) "at" constr(K) "with" constr(F) :=
let T := fresh "TEMP" in assert (T: E = F); [ | rewrites T at K; clear T ].

Tactic Notation "replaces" constr(E) "at" constr(K) "with" constr(F) "in" hyp(H) :=
let T := fresh "TEMP" in assert (T: E = F); [ | rewrites T at K in H; clear T ].

(**  ** Change *)

(** [changes] is like [change] except that it does not silently
 fail to perform its task. (Note that, [changes] is implemented
 using [rewrite], meaning that it might perform additional
 beta-reductions compared with the original [change] tactic. *)
(* --Note: should we support "changes (E1 = E2)" *)

Tactic Notation "changes" constr(E1) "with" constr(E2) "in" hyp(H) :=
asserts_rewrite (E1 = E2) in H; [ reflexivity | ].

Tactic Notation "changes" constr(E1) "with" constr(E2) :=
asserts_rewrite (E1 = E2); [ reflexivity | ].

Tactic Notation "changes" constr(E1) "with" constr(E2) "in" "*" :=
asserts_rewrite (E1 = E2) in *; [ reflexivity | ].


(* ================================================================= *)
(** ** Renaming *)

(** [renames X1 to Y1, ..., XN to YN] is a shorthand for a sequence of
  renaming operations [rename Xi into Yi]. *)

Tactic Notation "renames" ident(X1) "to" ident(Y1) :=
rename X1 into Y1.
Tactic Notation "renames" ident(X1) "to" ident(Y1) ","
ident(X2) "to" ident(Y2) :=
renames X1 to Y1; renames X2 to Y2.
Tactic Notation "renames" ident(X1) "to" ident(Y1) ","
ident(X2) "to" ident(Y2) "," ident(X3) "to" ident(Y3) :=
renames X1 to Y1; renames X2 to Y2, X3 to Y3.
Tactic Notation "renames" ident(X1) "to" ident(Y1) ","
ident(X2) "to" ident(Y2) "," ident(X3) "to" ident(Y3) ","
ident(X4) "to" ident(Y4) :=
renames X1 to Y1; renames X2 to Y2, X3 to Y3, X4 to Y4.
Tactic Notation "renames" ident(X1) "to" ident(Y1) ","
ident(X2) "to" ident(Y2) "," ident(X3) "to" ident(Y3) ","
ident(X4) "to" ident(Y4) "," ident(X5) "to" ident(Y5) :=
renames X1 to Y1; renames X2 to Y2, X3 to Y3, X4 to Y4, X5 to Y5.
Tactic Notation "renames" ident(X1) "to" ident(Y1) ","
ident(X2) "to" ident(Y2) "," ident(X3) "to" ident(Y3) ","
ident(X4) "to" ident(Y4) "," ident(X5) "to" ident(Y5) ","
ident(X6) "to" ident(Y6) :=
renames X1 to Y1; renames X2 to Y2, X3 to Y3, X4 to Y4, X5 to Y5, X6 to Y6.

(* ================================================================= *)
(** ** Unfolding *)

(** [unfolds] unfolds the head definition in the goal, i.e. if the
  goal has form [P x1 ... xN] then it calls [unfold P].
  If the goal is an equality, it tries to unfold the head constant
  on the left-hand side, and otherwise tries on the right-hand side.
  If the goal is a product, it calls [intros] first.
  -- warning: this tactic is overriden in LibReflect. *)

Ltac apply_to_head_of E cont :=
let go E :=
  let P := get_head E in cont P in
match E with
| forall _,_ => intros; apply_to_head_of E cont
| ?A = ?B => first [ go A | go B ]
| ?A => go A
end.

Ltac unfolds_base :=
match goal with |- ?G =>
 apply_to_head_of G ltac:(fun P => unfold P) end.

Tactic Notation "unfolds" :=
unfolds_base.

(** [unfolds in H] unfolds the head definition of hypothesis [H], i.e. if
  [H] has type [P x1 ... xN] then it calls [unfold P in H]. *)

Ltac unfolds_in_base H :=
match type of H with ?G =>
 apply_to_head_of G ltac:(fun P => unfold P in H) end.

Tactic Notation "unfolds" "in" hyp(H) :=
unfolds_in_base H.

(** [unfolds in H1,H2,..,HN] allows unfolding the head constant
  in several hypotheses at once. *)

Tactic Notation "unfolds" "in" hyp(H1) hyp(H2) :=
unfolds in H1; unfolds in H2.
Tactic Notation "unfolds" "in" hyp(H1) hyp(H2) hyp(H3) :=
unfolds in H1; unfolds in H2 H3.
Tactic Notation "unfolds" "in" hyp(H1) hyp(H2) hyp(H3) hyp(H4) :=
unfolds in H1; unfolds in H2 H3 H4.
Tactic Notation "unfolds" "in" hyp(H1) hyp(H2) hyp(H3) hyp(H4) hyp(H5) :=
unfolds in H1; unfolds in H2 H3 H4 H5.

(** [unfolds P1,..,PN] is a shortcut for [unfold P1,..,PN in *]. *)

Tactic Notation "unfolds" constr(F1) :=
unfold F1 in *.
Tactic Notation "unfolds" constr(F1) "," constr(F2) :=
unfold F1,F2 in *.
Tactic Notation "unfolds" constr(F1) "," constr(F2)
"," constr(F3) :=
unfold F1,F2,F3 in *.
Tactic Notation "unfolds" constr(F1) "," constr(F2)
"," constr(F3) "," constr(F4) :=
unfold F1,F2,F3,F4 in *.
Tactic Notation "unfolds" constr(F1) "," constr(F2)
"," constr(F3) "," constr(F4) "," constr(F5) :=
unfold F1,F2,F3,F4,F5 in *.
Tactic Notation "unfolds" constr(F1) "," constr(F2)
"," constr(F3) "," constr(F4) "," constr(F5) "," constr(F6) :=
unfold F1,F2,F3,F4,F5,F6 in *.
Tactic Notation "unfolds" constr(F1) "," constr(F2)
"," constr(F3) "," constr(F4) "," constr(F5)
"," constr(F6) "," constr(F7) :=
unfold F1,F2,F3,F4,F5,F6,F7 in *.
Tactic Notation "unfolds" constr(F1) "," constr(F2)
"," constr(F3) "," constr(F4) "," constr(F5)
"," constr(F6) "," constr(F7) "," constr(F8) :=
unfold F1,F2,F3,F4,F5,F6,F7,F8 in *.

(** [folds P1,..,PN] is a shortcut for [fold P1 in *; ..; fold PN in *]. *)

Tactic Notation "folds" constr(H) :=
fold H in *.
Tactic Notation "folds" constr(H1) "," constr(H2) :=
folds H1; folds H2.
Tactic Notation "folds" constr(H1) "," constr(H2) "," constr(H3) :=
folds H1; folds H2; folds H3.
Tactic Notation "folds" constr(H1) "," constr(H2) "," constr(H3)
"," constr(H4) :=
folds H1; folds H2; folds H3; folds H4.
Tactic Notation "folds" constr(H1) "," constr(H2) "," constr(H3)
"," constr(H4) "," constr(H5) :=
folds H1; folds H2; folds H3; folds H4; folds H5.

(* ================================================================= *)
(** ** Simplification *)

(** [simpls] is a shortcut for [simpl in *]. *)

Tactic Notation "simpls" :=
simpl in *.

(** [simpls P1,..,PN] is a shortcut for
  [simpl P1 in *; ..; simpl PN in *]. *)

Tactic Notation "simpls" constr(F1) :=
simpl F1 in *.
Tactic Notation "simpls" constr(F1) "," constr(F2) :=
simpls F1; simpls F2.
Tactic Notation "simpls" constr(F1) "," constr(F2)
"," constr(F3) :=
simpls F1; simpls F2; simpls F3.
Tactic Notation "simpls" constr(F1) "," constr(F2)
"," constr(F3) "," constr(F4) :=
simpls F1; simpls F2; simpls F3; simpls F4.

(** [unsimpl E] replaces all occurence of [X] by [E], where [X] is
 the result which the tactic [simpl] would give when applied to [E].
 It is useful to undo what [simpl] has simplified too far. *)

Tactic Notation "unsimpl" constr(E) :=
let F := (eval simpl in E) in change F with E.

(** [unsimpl E in H] is similar to [unsimpl E] but it applies
  inside a particular hypothesis [H]. *)

Tactic Notation "unsimpl" constr(E) "in" hyp(H) :=
let F := (eval simpl in E) in change F with E in H.

(** [unsimpl E in *] applies [unsimpl E] everywhere possible.
  [unsimpls E] is a synonymous. *)

Tactic Notation "unsimpl" constr(E) "in" "*" :=
let F := (eval simpl in E) in change F with E in *.
Tactic Notation "unsimpls" constr(E) :=
unsimpl E in *.

(** [nosimpl t] protects the Coq term[t] against some forms of
  simplification. See Gonthier's work for details on this trick. *)

Notation "'nosimpl' t" := (match tt with tt => t end)
(at level 10).

(* ================================================================= *)
(** ** Reduction *)

Tactic Notation "hnfs" := hnf in *.

(* ================================================================= *)
(** ** Substitution *)

(** [substs] does the same as [subst], except that it does not fail
  when there are circular equalities in the context. *)

Tactic Notation "substs" :=
repeat (match goal with H: ?x = ?y |- _ =>
          first [ subst x | subst y ] end).

(** Implementation of [substs below], which allows to call
  [subst] on all the hypotheses that lie beyond a given
  position in the proof context. *)

Ltac substs_below limit :=
match goal with H: ?T |- _ =>
match T with
| limit => idtac
| ?x = ?y =>
  first [ subst x; substs_below limit
        | subst y; substs_below limit
        | generalizes H; substs_below limit; intro ]
end end.

(** [substs below body E] applies [subst] on all equalities that appear
  in the context below the first hypothesis whose body is [E].
  If there is no such hypothesis in the context, it is equivalent
  to [subst]. For instance, if [H] is an hypothesis, then
  [substs below H] will substitute equalities below hypothesis [H]. *)

Tactic Notation "substs" "below" "body" constr(M) :=
substs_below M.

(** [substs below H] applies [subst] on all equalities that appear
  in the context below the hypothesis named [H]. Note that
  the current implementation is technically incorrect since it
  will confuse different hypotheses with the same body. *)

Tactic Notation "substs" "below" hyp(H) :=
match type of H with ?M => substs below body M end.

(** [subst_hyp H] substitutes the equality contained in the
  first hypothesis from the context. *)

Ltac intro_subst_hyp := fail. (* definition further on *)

(** [subst_hyp H] substitutes the equality contained in [H]. *)

Ltac subst_hyp_base H :=
match type of H with
| (_,_,_,_,_) = (_,_,_,_,_) => injection H; clear H; do 4 intro_subst_hyp
| (_,_,_,_) = (_,_,_,_) => injection H; clear H; do 4 intro_subst_hyp
| (_,_,_) = (_,_,_) => injection H; clear H; do 3 intro_subst_hyp
| (_,_) = (_,_) => injection H; clear H; do 2 intro_subst_hyp
| ?x = ?x => clear H
| ?x = ?y => first [ subst x | subst y ]
end.

Tactic Notation "subst_hyp" hyp(H) := subst_hyp_base H.

Ltac intro_subst_hyp ::=
let H := fresh "TEMP" in intros H; subst_hyp H.

(** [intro_subst] is a shorthand for [intro H; subst_hyp H]:
  it introduces and substitutes the equality at the head
  of the current goal. *)

Tactic Notation "intro_subst" :=
let H := fresh "TEMP" in intros H; subst_hyp H.

(** [subst_local] substitutes all local definition from the context *)

Ltac subst_local :=
repeat match goal with H:=_ |- _ => subst H end.

(** [subst_eq E] takes an equality [x = t] and replace [x]
  with [t] everywhere in the goal *)

Ltac subst_eq_base E :=
let H := fresh "TEMP" in lets H: E; subst_hyp H.

Tactic Notation "subst_eq" constr(E) :=
subst_eq_base E.

(* ================================================================= *)
(** ** Tactics to Work with Proof Irrelevance *)

Require Import Coq.Logic.ProofIrrelevance.

(** [pi_rewrite E] replaces [E] of type [Prop] with a fresh
  unification variable, and is thus a practical way to
  exploit proof irrelevance, without writing explicitly
  [rewrite (proof_irrelevance E E')]. Particularly useful
  when [E'] is a big expression. *)

Ltac pi_rewrite_base E rewrite_tac :=
let E' := fresh "TEMP" in let T := type of E in evar (E':T);
rewrite_tac (@proof_irrelevance _ E E'); subst E'.

Tactic Notation "pi_rewrite" constr(E) :=
pi_rewrite_base E ltac:(fun X => rewrite X).
Tactic Notation "pi_rewrite" constr(E) "in" hyp(H) :=
pi_rewrite_base E ltac:(fun X => rewrite X in H).

(* ================================================================= *)
(** ** Proving Equalities *)

(** The tactic [fequal] enhances Coq's tactic [f_equal], which does not
  simplify equalities between tuples, nor between dependent pairs of
  the form [exist _ _] or [existT _ _]. For support of dependent pairs,
  the file [LibEqual] must be imported.

  Subgoals solvable by [reflexivity] are automatically discharged.
  See also the the variant [fequals], which discharges more subgoals. *)

(** Note: only [args_eq_2] is actually useful for the implementation of
  [fequal], if we rely on Coq's [f_equal] tactic for other arities.
  We provide these lemmas to show the pattern of lemmas to exploit
  for implementing [fequal] independently of [f_equal]. *)

Section FuncEq.
Variables (A1 A2 A3 A4 A5 A6 A7 B : Type).

Lemma args_eq_1 : forall (f:A1->B) x1 y1,
x1 = y1 ->
f x1 = f y1.
Proof using. intros. subst. auto. Qed.

Lemma args_eq_2 : forall (f:A1->A2->B) x1 y1 x2 y2,
x1 = y1 -> x2 = y2 ->
f x1 x2 = f y1 y2.
Proof using. intros. subst. auto. Qed.

Lemma args_eq_3 : forall (f:A1->A2->A3->B) x1 y1 x2 y2 x3 y3,
x1 = y1 -> x2 = y2 -> x3 = y3 ->
f x1 x2 x3 = f y1 y2 y3.
Proof using. intros. subst. auto. Qed.

Lemma args_eq_4 : forall (f:A1->A2->A3->A4->B) x1 y1 x2 y2 x3 y3 x4 y4,
x1 = y1 -> x2 = y2 -> x3 = y3 -> x4 = y4 ->
f x1 x2 x3 x4 = f y1 y2 y3 y4.
Proof using. intros. subst. auto. Qed.

Lemma args_eq_5 : forall (f:A1->A2->A3->A4->A5->B) x1 y1 x2 y2 x3 y3 x4 y4 x5 y5,
x1 = y1 -> x2 = y2 -> x3 = y3 -> x4 = y4 -> x5 = y5 ->
f x1 x2 x3 x4 x5 = f y1 y2 y3 y4 y5.
Proof using. intros. subst. auto. Qed.

Lemma args_eq_6 : forall (f:A1->A2->A3->A4->A5->A6->B) x1 y1 x2 y2 x3 y3 x4 y4 x5 y5 x6 y6,
x1 = y1 -> x2 = y2 -> x3 = y3 -> x4 = y4 -> x5 = y5 -> x6 = y6 ->
f x1 x2 x3 x4 x5 x6 = f y1 y2 y3 y4 y5 y6.
Proof using. intros. subst. auto. Qed.

Lemma args_eq_7 : forall (f:A1->A2->A3->A4->A5->A6->A7->B) x1 y1 x2 y2 x3 y3 x4 y4 x5 y5 x6 y6 x7 y7,
x1 = y1 -> x2 = y2 -> x3 = y3 -> x4 = y4 -> x5 = y5 -> x6 = y6 -> x7 = y7 ->
f x1 x2 x3 x4 x5 x6 x7 = f y1 y2 y3 y4 y5 y6 y7.
Proof using. intros. subst. auto. Qed.

End FuncEq.

Ltac fequal_post :=
try solve [ reflexivity ].

(** [fequal_support_for_exist], implemented in [LibEqual], is meant
 to simplify goals of the form [exist _ _ = exist _ _ ] and
 [existT _ _ = existT _ _], by exploiting proof irrelevance. *)

Ltac fequal_support_for_exist tt :=
fail.

(** For a n-ary tuple, [fequal], unlike [f_equal] enforces a recursive call
  on the (n-1)-ary tuple associated with the right component. *)

Ltac fequal_base :=
match goal with
| |- (_,_,_) = (_,_,_) =>  apply args_eq_2; [ fequal_base | ]
| |- _ => first
          [ fequal_support_for_exist tt
          | apply args_eq_1
          | apply args_eq_2
          | apply args_eq_3
          | apply args_eq_4
          | apply args_eq_5
          | apply args_eq_6
          | apply args_eq_7
          | f_equal (* fallback to Coq [f_equal] *) ]
end.

Tactic Notation "fequal" :=
fequal_base; fequal_post.

(** [fequals] is the same as [fequal] except that it tries and solve
  all trivial subgoals, using [reflexivity] and [congruence]
  (as well as the proof-irrelevance principle).
  [fequals] applies to goals of the form [f x1 .. xN = f y1 .. yN]
  and produces some subgoals of the form [xi = yi]). *)

Ltac fequals_post :=
try solve [ reflexivity | congruence | apply proof_irrelevance ].

Tactic Notation "fequals" :=
fequal; fequals_post.

(** [fequals_rec] calls [fequals] recursively.
  It is equivalent to [repeat (progress fequals)]. *)

Tactic Notation "fequals_rec" :=
repeat (progress fequals).


(* ################################################################# *)
(** * Inversion *)

(* ================================================================= *)
(** ** Basic Inversion *)

(** [invert keep H] is same to [inversion H] except that it puts all the
  facts obtained in the goal. The keyword [keep] means that the
  hypothesis [H] should not be removed. *)

Tactic Notation "invert" "keep" hyp(H) :=
pose ltac_mark; inversion H; gen_until_mark.

(** [invert keep H as X1 .. XN] is the same as [inversion H as ...] except
  that only hypotheses which are not variable need to be named
  explicitely, in a similar fashion as [introv] is used to name
  only hypotheses. *)

Tactic Notation "invert" "keep" hyp(H) "as" simple_intropattern(I1) :=
invert keep H; introv I1.
Tactic Notation "invert" "keep" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) :=
invert keep H; introv I1 I2.
Tactic Notation "invert" "keep" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) :=
invert keep H; introv I1 I2 I3.

(** [invert H] is same to [inversion H] except that it puts all the
  facts obtained in the goal and clears hypothesis [H].
  In other words, it is equivalent to [invert keep H; clear H]. *)

Tactic Notation "invert" hyp(H) :=
invert keep H; clear H.

(** [invert H as X1 .. XN] is the same as [invert keep H as X1 .. XN]
  but it also clears hypothesis [H]. *)

Tactic Notation "invert_tactic" hyp(H) tactic(tac) :=
let H' := fresh "TEMP" in rename H into H'; tac H'; clear H'.
Tactic Notation "invert" hyp(H) "as" simple_intropattern(I1) :=
invert_tactic H (fun H => invert keep H as I1).
Tactic Notation "invert" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) :=
invert_tactic H (fun H => invert keep H as I1 I2).
Tactic Notation "invert" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) :=
invert_tactic H (fun H => invert keep H as I1 I2 I3).

(* ================================================================= *)
(** ** Inversion with Substitution *)

(** Our inversion tactics is able to get rid of dependent equalities
  generated by [inversion], using proof irrelevance. *)

(* --we do not import Eqdep because it imports nasty hints automatically
  From TLC Require Import Eqdep. *)

Require Import Coq.Program.Equality.


Ltac inverts_tactic H i1 i2 i3 i4 i5 i6 :=
let rec go i1 i2 i3 i4 i5 i6 :=
  match goal with
  | |- (ltac_Mark -> _) => intros _
  | |- (?x = ?y -> _) => let H := fresh "TEMP" in intro H;
                         first [ subst x | subst y ];
                         go i1 i2 i3 i4 i5 i6
  | |- (existT ?P ?p ?x = existT ?P ?p ?y -> _) =>
       let H := fresh "TEMP" in intro H;
       generalize (@inj_pair2 _ P p x y H);
       clear H; go i1 i2 i3 i4 i5 i6
  | |- (?P -> ?Q) => i1; go i2 i3 i4 i5 i6 ltac:(intro)
  | |- (forall _, _) => intro; go i1 i2 i3 i4 i5 i6
  end in
generalize ltac_mark; invert keep H; go i1 i2 i3 i4 i5 i6;
unfold eq' in *.

(** [inverts keep H] is same to [invert keep H] except that it
  applies [subst] to all the equalities generated by the inversion. *)

Tactic Notation "inverts" "keep" hyp(H) :=
inverts_tactic H ltac:(intro) ltac:(intro) ltac:(intro)
                 ltac:(intro) ltac:(intro) ltac:(intro).

(** [inverts keep H as X1 .. XN] is the same as
  [invert keep H as X1 .. XN] except that it applies [subst] to all the
  equalities generated by the inversion *)

Tactic Notation "inverts" "keep" hyp(H) "as" simple_intropattern(I1) :=
inverts_tactic H ltac:(intros I1)
 ltac:(intro) ltac:(intro) ltac:(intro) ltac:(intro) ltac:(intro).
Tactic Notation "inverts" "keep" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) :=
inverts_tactic H ltac:(intros I1) ltac:(intros I2)
 ltac:(intro) ltac:(intro) ltac:(intro) ltac:(intro).
Tactic Notation "inverts" "keep" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) :=
inverts_tactic H ltac:(intros I1) ltac:(intros I2) ltac:(intros I3)
 ltac:(intro) ltac:(intro) ltac:(intro).
Tactic Notation "inverts" "keep" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4) :=
inverts_tactic H ltac:(intros I1) ltac:(intros I2) ltac:(intros I3)
 ltac:(intros I4) ltac:(intro) ltac:(intro).
Tactic Notation "inverts" "keep" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4)
simple_intropattern(I5) :=
inverts_tactic H ltac:(intros I1) ltac:(intros I2) ltac:(intros I3)
 ltac:(intros I4) ltac:(intros I5) ltac:(intro).
Tactic Notation "inverts" "keep" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4)
simple_intropattern(I5) simple_intropattern(I6) :=
inverts_tactic H ltac:(intros I1) ltac:(intros I2) ltac:(intros I3)
 ltac:(intros I4) ltac:(intros I5) ltac:(intros I6).

(** [inverts H] is same to [inverts keep H] except that it
  clears hypothesis [H]. *)

Tactic Notation "inverts" hyp(H) :=
inverts keep H; try clear H.

(** [inverts H as X1 .. XN] is the same as [inverts keep H as X1 .. XN]
  but it also clears the hypothesis [H]. *)

Tactic Notation "inverts_tactic" hyp(H) tactic(tac) :=
let H' := fresh "TEMP" in rename H into H'; tac H'; clear H'.
Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1) :=
invert_tactic H (fun H => inverts keep H as I1).
Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) :=
invert_tactic H (fun H => inverts keep H as I1 I2).
Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) :=
invert_tactic H (fun H => inverts keep H as I1 I2 I3).
Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4) :=
invert_tactic H (fun H => inverts keep H as I1 I2 I3 I4).
Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4)
simple_intropattern(I5) :=
invert_tactic H (fun H => inverts keep H as I1 I2 I3 I4 I5).
Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4)
simple_intropattern(I5) simple_intropattern(I6) :=
invert_tactic H (fun H => inverts keep H as I1 I2 I3 I4 I5 I6).

(** [inverts H as] performs an inversion on hypothesis [H], substitutes
  generated equalities, and put in the goal the other freshly-created
  hypotheses, for the user to name explicitly.
  [inverts keep H as] is the same except that it does not clear [H].
  --Note: maybe reimplement [inverts] above using this one *)

Ltac inverts_as_tactic H :=
let rec go tt :=
  match goal with
  | |- (ltac_Mark -> _) => intros _
  | |- (?x = ?y -> _) => let H := fresh "TEMP" in intro H;
                         first [ subst x | subst y ];
                         go tt
  | |- (existT ?P ?p ?x = existT ?P ?p ?y -> _) =>
       let H := fresh "TEMP" in intro H;
       generalize (@inj_pair2 _ P p x y H);
       clear H; go tt
  | |- (forall _, _) =>
     intro; let H := get_last_hyp tt in mark_to_generalize H; go tt
  end in
pose ltac_mark; inversion H;
generalize ltac_mark; gen_until_mark;
go tt; gen_to_generalize; unfolds ltac_to_generalize;
unfold eq' in *.

Tactic Notation "inverts" "keep" hyp(H) "as" :=
inverts_as_tactic H.

Tactic Notation "inverts" hyp(H) "as" :=
inverts_as_tactic H; clear H.

Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4)
simple_intropattern(I5) simple_intropattern(I6) simple_intropattern(I7) :=
inverts H as; introv I1 I2 I3 I4 I5 I6 I7.
Tactic Notation "inverts" hyp(H) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4)
simple_intropattern(I5) simple_intropattern(I6) simple_intropattern(I7)
simple_intropattern(I8) :=
inverts H as; introv I1 I2 I3 I4 I5 I6 I7 I8.

(** [lets_inverts E as I1 .. IN] is intuitively equivalent to
  [inverts E], with the difference that it applies to any
  expression and not just to the name of an hypothesis. *)

Ltac lets_inverts_base E cont :=
let H := fresh "TEMP" in lets H: E; try cont H.

Tactic Notation "lets_inverts" constr(E) :=
lets_inverts_base E ltac:(fun H => inverts H).
Tactic Notation "lets_inverts" constr(E) "as" simple_intropattern(I1) :=
lets_inverts_base E ltac:(fun H => inverts H as I1).
Tactic Notation "lets_inverts" constr(E) "as" simple_intropattern(I1)
simple_intropattern(I2) :=
lets_inverts_base E ltac:(fun H => inverts H as I1 I2).
Tactic Notation "lets_inverts" constr(E) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) :=
lets_inverts_base E ltac:(fun H => inverts H as I1 I2 I3).
Tactic Notation "lets_inverts" constr(E) "as" simple_intropattern(I1)
simple_intropattern(I2) simple_intropattern(I3) simple_intropattern(I4) :=
lets_inverts_base E ltac:(fun H => inverts H as I1 I2 I3 I4).


(* ================================================================= *)
(** ** Injection with Substitution *)

(** Underlying implementation of [injects] *)

Ltac injects_tactic H :=
let rec go _ :=
  match goal with
  | |- (ltac_Mark -> _) => intros _
  | |- (?x = ?y -> _) => let H := fresh "TEMP" in intro H;
                         first [ subst x | subst y | idtac ];
                         go tt
  end in
generalize ltac_mark; injection H; go tt.

(** [injects keep H] takes an hypothesis [H] of the form
  [C a1 .. aN = C b1 .. bN] and substitute all equalities
  [ai = bi] that have been generated. *)

Tactic Notation "injects" "keep" hyp(H) :=
injects_tactic H.

(** [injects H] is similar to [injects keep H] but clears
  the hypothesis [H]. *)

Tactic Notation "injects" hyp(H) :=
injects_tactic H; clear H.

(** [inject H as X1 .. XN] is the same as [injection]
  followed by [intros X1 .. XN] *)

Tactic Notation "inject" hyp(H) :=
injection H.
Tactic Notation "inject" hyp(H) "as" ident(X1) :=
injection H; intros X1.
Tactic Notation "inject" hyp(H) "as" ident(X1) ident(X2) :=
injection H; intros X1 X2.
Tactic Notation "inject" hyp(H) "as" ident(X1) ident(X2) ident(X3) :=
injection H; intros X1 X2 X3.
Tactic Notation "inject" hyp(H) "as" ident(X1) ident(X2) ident(X3)
ident(X4) :=
injection H; intros X1 X2 X3 X4.
Tactic Notation "inject" hyp(H) "as" ident(X1) ident(X2) ident(X3)
ident(X4) ident(X5) :=
injection H; intros X1 X2 X3 X4 X5.

(* ================================================================= *)
(** ** Inversion and Injection with Substitution --rough implementation *)

(** The tactics [inversions] and [injections] provided in this section
  are similar to [inverts] and [injects] except that they perform
  substitution on all equalities from the context and not only
  the ones freshly generated. The counterpart is that they have
  simpler implementations.

  DEPRECATED: these tactics should no longer be used. *)

(** [inversions keep H] is the same as [inversions H] but it does
  not clear hypothesis [H]. *)

Tactic Notation "inversions" "keep" hyp(H) :=
inversion H; subst.

(** [inversions H] is a shortcut for [inversion H] followed by [subst]
  and [clear H].
  It is a rough implementation of [inverts keep H] which behave
  badly when the proof context already contains equalities.
  It is provided in case the better implementation turns out to be
  too slow. *)

Tactic Notation "inversions" hyp(H) :=
inversion H; subst; try clear H.

(** [injections keep H] is the same as [injection H] followed
  by [intros] and [subst]. It is a rough implementation of
  [injects keep H] which behave
  badly when the proof context already contains equalities,
  or when the goal starts with a forall or an implication. *)

Tactic Notation "injections" "keep" hyp(H) :=
injection H; intros; subst.

(** [injections H] is the same as [injection H] followed
  by [clear H] and [intros] and [subst]. It is a rough
  implementation of [injects keep H] which behave
  badly when the proof context already contains equalities,
  or when the goal starts with a forall or an implication. *)

Tactic Notation "injections" "keep" hyp(H) :=
injection H; clear H; intros; subst.

(* ================================================================= *)
(** ** Case Analysis *)

(** [cases] is similar to [case_eq E] except that it generates the
  equality in the context and not in the goal, and generates the
  equality the other way round. The syntax [cases E as H]
  allows specifying the name [H] of that hypothesis. *)

Tactic Notation "cases" constr(E) "as" ident(H) :=
let X := fresh "TEMP" in
set (X := E) in *; def_to_eq_sym X H E;
destruct X.

Tactic Notation "cases" constr(E) :=
let H := fresh "Eq" in cases E as H.

(** [case_if_post H] is to be defined later as a tactic to clean
  up hypothesis [H] and the goal.
  By defaults, it looks for obvious contradictions.
  Currently, this tactic is extended in LibReflect to clean up
  boolean propositions. *)

Ltac case_if_post H :=
tryfalse.

(** [case_if] looks for a pattern of the form [if ?B then ?E1 else ?E2]
  in the goal, and perform a case analysis on [B] by calling
  [destruct B]. Subgoals containing a contradiction are discarded.
  [case_if] looks in the goal first, and otherwise in the
  first hypothesis that contains an [if] statement.
  [case_if in H] can be used to specify which hypothesis to consider.
  Syntaxes [case_if as Eq] and [case_if in H as Eq] allows to name
  the hypothesis coming from the case analysis. *)

Ltac case_if_on_tactic_core E Eq :=
match type of E with
| {_}+{_} => destruct E as [Eq | Eq]
| _ => let X := fresh "TEMP" in
       sets_eq <- X Eq: E;
       destruct X
end.

Ltac case_if_on_tactic E Eq :=
case_if_on_tactic_core E Eq; case_if_post Eq.

Tactic Notation "case_if_on" constr(E) "as" simple_intropattern(Eq) :=
case_if_on_tactic E Eq.

Tactic Notation "case_if" "as" simple_intropattern(Eq) :=
match goal with
| |- context [if ?B then _ else _] => case_if_on B as Eq
| K: context [if ?B then _ else _] |- _ => case_if_on B as Eq
end.

Tactic Notation "case_if" "in" hyp(H) "as" simple_intropattern(Eq) :=
match type of H with context [if ?B then _ else _] =>
  case_if_on B as Eq end.

Tactic Notation "case_if" :=
let Eq := fresh "C" in case_if as Eq.

Tactic Notation "case_if" "in" hyp(H) :=
let Eq := fresh "C" in case_if in H as Eq.

(** [cases_if] is similar to [case_if] with two main differences:
  if it creates an equality of the form [x = y] and then
  substitutes it in the goal *)

Ltac cases_if_on_tactic_core E Eq :=
match type of E with
| {_}+{_} => destruct E as [Eq|Eq]; try subst_hyp Eq
| _ => let X := fresh "TEMP" in
       sets_eq <- X Eq: E;
       destruct X
end.

Ltac cases_if_on_tactic E Eq :=
cases_if_on_tactic_core E Eq; tryfalse; case_if_post Eq.

Tactic Notation "cases_if_on" constr(E) "as" simple_intropattern(Eq) :=
cases_if_on_tactic E Eq.

Tactic Notation "cases_if" "as" simple_intropattern(Eq) :=
match goal with
| |- context [if ?B then _ else _] => cases_if_on B as Eq
| K: context [if ?B then _ else _] |- _ => cases_if_on B as Eq
end.

Tactic Notation "cases_if" "in" hyp(H) "as" simple_intropattern(Eq) :=
match type of H with context [if ?B then _ else _] =>
  cases_if_on B as Eq end.

Tactic Notation "cases_if" :=
let Eq := fresh "C" in cases_if as Eq.

Tactic Notation "cases_if" "in" hyp(H) :=
let Eq := fresh "C" in cases_if in H as Eq.

(** [case_ifs] is like [repeat case_if] *)

Ltac case_ifs_core :=
repeat case_if.

Tactic Notation "case_ifs" :=
case_ifs_core.

(** [destruct_if] looks for a pattern of the form [if ?B then ?E1 else ?E2]
  in the goal, and perform a case analysis on [B] by calling
  [destruct B]. It looks in the goal first, and otherwise in the
  first hypothesis that contains an [if] statement. *)

Ltac destruct_if_post := tryfalse.

Tactic Notation "destruct_if"
"as" simple_intropattern(Eq1) simple_intropattern(Eq2) :=
match goal with
| |- context [if ?B then _ else _] => destruct B as [Eq1|Eq2]
| K: context [if ?B then _ else _] |- _ => destruct B as [Eq1|Eq2]
end;
destruct_if_post.

Tactic Notation "destruct_if" "in" hyp(H)
"as" simple_intropattern(Eq1) simple_intropattern(Eq2) :=
match type of H with context [if ?B then _ else _] =>
  destruct B as [Eq1|Eq2] end;
destruct_if_post.

Tactic Notation "destruct_if" "as" simple_intropattern(Eq) :=
destruct_if as Eq Eq.
Tactic Notation "destruct_if" "in" hyp(H) "as" simple_intropattern(Eq) :=
destruct_if in H as Eq Eq.

Tactic Notation "destruct_if" :=
let Eq := fresh "C" in destruct_if as Eq Eq.
Tactic Notation "destruct_if" "in" hyp(H) :=
let Eq := fresh "C" in destruct_if in H as Eq Eq.

(** [cases'] is provided for compatibility with [remember]. *)

(** [cases' E] is similar to [case_eq E] except that it generates the
  equality in the context and not in the goal. The syntax [cases' E as H]
  allows specifying the name [H] of that hypothesis. *)

Tactic Notation "cases'" constr(E) "as" ident(H) :=
let X := fresh "TEMP" in
set (X := E) in *; def_to_eq X H E;
destruct X.

Tactic Notation "cases'" constr(E) :=
let x := fresh "Eq" in cases' E as H.

(** [cases_if'] is similar to [cases_if] except that it generates
  the symmetric equality. *)

Ltac cases_if_on' E Eq :=
match type of E with
| {_}+{_} => destruct E as [Eq|Eq]; try subst_hyp Eq
| _ => let X := fresh "TEMP" in
       sets_eq X Eq: E;
       destruct X
end; case_if_post Eq.

Tactic Notation "cases_if'" "as" simple_intropattern(Eq) :=
match goal with
| |- context [if ?B then _ else _] => cases_if_on' B Eq
| K: context [if ?B then _ else _] |- _ => cases_if_on' B Eq
end.

Tactic Notation "cases_if'" :=
let Eq := fresh "C" in cases_if' as Eq.

(* ################################################################# *)
(** * Induction *)

(** [inductions E] is a shorthand for [dependent induction E].
  [inductions E gen X1 .. XN] is a shorthand for
  [dependent induction E generalizing X1 .. XN]. *)



Ltac inductions_post :=
unfold eq' in *.

Tactic Notation "inductions" ident(E) :=
dependent induction E; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) :=
dependent induction E generalizing X1; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) ident(X2) :=
dependent induction E generalizing X1 X2; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) ident(X2)
ident(X3) :=
dependent induction E generalizing X1 X2 X3; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) ident(X2)
ident(X3) ident(X4) :=
dependent induction E generalizing X1 X2 X3 X4; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) ident(X2)
ident(X3) ident(X4) ident(X5) :=
dependent induction E generalizing X1 X2 X3 X4 X5; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) ident(X2)
ident(X3) ident(X4) ident(X5) ident(X6) :=
dependent induction E generalizing X1 X2 X3 X4 X5 X6; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) ident(X2)
ident(X3) ident(X4) ident(X5) ident(X6) ident(X7) :=
dependent induction E generalizing X1 X2 X3 X4 X5 X6 X7; inductions_post.
Tactic Notation "inductions" ident(E) "gen" ident(X1) ident(X2)
ident(X3) ident(X4) ident(X5) ident(X6) ident(X7) ident(X8) :=
dependent induction E generalizing X1 X2 X3 X4 X5 X6 X7 X8; inductions_post.

(** [induction_wf IH: E X] is used to apply the well-founded induction
  principle, for a given well-founded relation. It applies to a goal
  [PX] where [PX] is a proposition on [X]. First, it sets up the
  goal in the form [(fun a => P a) X], using [pattern X], and then
  it applies the well-founded induction principle instantiated on [E].

  Here [E] may be either:
 - a proof of [wf R] for [R] of type [A->A->Prop]
 - a binary relation of type [A->A->Prop]
 - a measure of type [A -> nat] // only when LibWf is used. *)

(* DEPRECATED
Tactic Notation "induction_wf" ident(IH) ":" constr(E) ident(X) :=
pattern X; apply (well_founded_ind E); clear X; intros X IH.
*)

Ltac induction_wf_process_wf_hyp tt := (* refined in LibWf *)
idtac.

Ltac induction_wf_process_measure E := (* refined in LibWf *)
fail.

Ltac induction_wf_core_then IH E X cont :=
let clearX tt :=
  first [ clear X | fail 3 "the variable on which the induction is done appears in the hypotheses" ] in
pattern X;
first [ eapply (@well_founded_ind _ E)
      | eapply (@well_founded_ind _ (E _))
      | eapply (@well_founded_ind _ (E _ _))
      | eapply (@well_founded_ind _ (E _ _ _))
      | induction_wf_process_measure E
      | applys well_founded_ind E ];
clearX tt;
first [ induction_wf_process_wf_hyp tt
      | intros X IH; cont tt ].

Ltac induction_wf_core IH E X :=
induction_wf_core_then IH E X ltac:(fun _ => idtac).

Tactic Notation "induction_wf" ident(IH) ":" constr(E) ident(X) :=
induction_wf_core IH E X.

(** Induction on the height of a derivation: the helper tactic
  [induct_height] helps proving the equivalence of the auxiliary
  judgment that includes a counter for the maximal height
  (see LibTacticsDemos for an example) *)

Require Import Coq.Arith.Compare_dec.
Require Import Coq.micromega.Lia.

Lemma induct_height_max2 : forall n1 n2 : nat,
exists n, n1 < n /\ n2 < n.
Proof using.
intros. destruct (lt_dec n1 n2).
exists (S n2). lia.
exists (S n1). lia.
Qed.

Ltac induct_height_step x :=
match goal with
| H: exists _, _ |- _ =>
   let n := fresh "n" in let y := fresh "x" in
   destruct H as [n ?];
   forwards (y&?&?): induct_height_max2 n x;
   induct_height_step y
| _ => exists (S x); eauto
end.

Ltac induct_height := induct_height_step O.

(* ################################################################# *)
(** * Coinduction *)

(** Tactic [cofixs IH] is like [cofix IH] except that the
  coinduction hypothesis is tagged in the form [IH: COIND P]
  instead of being just [IH: P]. This helps other tactics
  clearing the coinduction hypothesis using [clear_coind] *)

Definition COIND (P:Prop) := P.

Tactic Notation "cofixs" ident(IH) :=
cofix IH;
match type of IH with ?P => change P with (COIND P) in IH end.

(** Tactic [clear_coind] clears all the coinduction hypotheses,
  assuming that they have been tagged *)

Ltac clear_coind :=
repeat match goal with H: COIND _ |- _ => clear H end.

(** Tactic [abstracts tac] is like [abstract tac] except that
  it clears the coinduction hypotheses so that the productivity
  check will be happy. For example, one can use [abstracts lia]
  to obtain the same behavior as [lia] but with an auxiliary
  lemma being generated. *)

Tactic Notation "abstracts" tactic(tac) :=
clear_coind; tac.


(* ################################################################# *)
(** * Decidable Equality *)

(** [decides_equality] is the same as [decide equality] excepts that it
  is able to unfold definitions at head of the current goal. *)

Ltac decides_equality_tactic :=
first [ decide equality | progress(unfolds); decides_equality_tactic ].

Tactic Notation "decides_equality" :=
decides_equality_tactic.

(* ################################################################# *)
(** * Equivalence *)

(** [iff H] can be used to prove an equivalence [P <-> Q] and name [H]
  the hypothesis obtained in each case. The syntaxes [iff] and [iff H1 H2]
  are also available to specify zero or two names. The tactic [iff <- H]
  swaps the two subgoals, i.e. produces (Q -> P) as first subgoal. *)

Lemma iff_intro_swap : forall (P Q : Prop),
(Q -> P) -> (P -> Q) -> (P <-> Q).
Proof using. intuition. Qed.

Tactic Notation "iff" simple_intropattern(H1) simple_intropattern(H2) :=
split; [ intros H1 | intros H2 ].
Tactic Notation "iff" simple_intropattern(H) :=
iff H H.
Tactic Notation "iff" :=
let H := fresh "H" in iff H.

Tactic Notation "iff" "<-" simple_intropattern(H1) simple_intropattern(H2) :=
apply iff_intro_swap; [ intros H1 | intros H2 ].
Tactic Notation "iff" "<-" simple_intropattern(H) :=
iff <- H H.
Tactic Notation "iff" "<-" :=
let H := fresh "H" in iff <- H.

(* ################################################################# *)
(** * N-ary Conjunctions and Disjunctions *)

(** N-ary Conjunctions Splitting in Goals *)

(** Underlying implementation of [splits]. *)

Ltac splits_tactic N :=
match N with
| O => fail
| S O => idtac
| S ?N' => split; [| splits_tactic N']
end.

Ltac unfold_goal_until_conjunction :=
match goal with
| |- _ /\ _ => idtac
| _ => progress(unfolds); unfold_goal_until_conjunction
end.

Ltac get_term_conjunction_arity T :=
match T with
| _ /\ _ /\ _ /\ _ /\ _ /\ _ /\ _ /\ _ => constr:(8)
| _ /\ _ /\ _ /\ _ /\ _ /\ _ /\ _ => constr:(7)
| _ /\ _ /\ _ /\ _ /\ _ /\ _ => constr:(6)
| _ /\ _ /\ _ /\ _ /\ _ => constr:(5)
| _ /\ _ /\ _ /\ _ => constr:(4)
| _ /\ _ /\ _ => constr:(3)
| _ /\ _ => constr:(2)
| _ -> ?T' => get_term_conjunction_arity T'
| _ => let P := get_head T in
       let T' := eval unfold P in T in
       match T' with
       | T => fail 1
       | _ => get_term_conjunction_arity T'
       end
       (* --todo: warning this can loop... *)
end.

Ltac get_goal_conjunction_arity :=
match goal with |- ?T => get_term_conjunction_arity T end.

(** [splits] applies to a goal of the form [(T1 /\ .. /\ TN)] and
  destruct it into [N] subgoals [T1] .. [TN]. If the goal is not a
  conjunction, then it unfolds the head definition. *)

Tactic Notation "splits" :=
unfold_goal_until_conjunction;
let N := get_goal_conjunction_arity in
splits_tactic N.

(** [splits N] is similar to [splits], except that it will unfold as many
  definitions as necessary to obtain an [N]-ary conjunction. *)

Tactic Notation "splits" constr(N) :=
let N := number_to_nat N in
splits_tactic N.

(** N-ary Conjunctions Deconstruction *)

(** Underlying implementation of [destructs]. *)

Ltac destructs_conjunction_tactic N T :=
match N with
| 2 => destruct T as [? ?]
| 3 => destruct T as [? [? ?]]
| 4 => destruct T as [? [? [? ?]]]
| 5 => destruct T as [? [? [? [? ?]]]]
| 6 => destruct T as [? [? [? [? [? ?]]]]]
| 7 => destruct T as [? [? [? [? [? [? ?]]]]]]
end.

(** [destructs T] allows destructing a term [T] which is a N-ary
  conjunction. It is equivalent to [destruct T as (H1 .. HN)],
  except that it does not require to manually specify N different
  names. *)

Tactic Notation "destructs" constr(T) :=
let TT := type of T in
let N := get_term_conjunction_arity TT in
destructs_conjunction_tactic N T.

(** [destructs N T] is equivalent to [destruct T as (H1 .. HN)],
  except that it does not require to manually specify N different
  names. Remark that it is not restricted to N-ary conjunctions. *)

Tactic Notation "destructs" constr(N) constr(T) :=
let N := number_to_nat N in
destructs_conjunction_tactic N T.

(** Proving Goals that are N-ary Disjunctions *)

(** Underlying implementation of [branch]. *)

Ltac branch_tactic K N :=
match constr:((K,N)) with
| (_,0) => fail 1
| (0,_) => fail 1
| (1,1) => idtac
| (1,_) => left
| (S ?K', S ?N') => right; branch_tactic K' N'
end.

Ltac unfold_goal_until_disjunction :=
match goal with
| |- _ \/ _ => idtac
| _ => progress(unfolds); unfold_goal_until_disjunction
end.

Ltac get_term_disjunction_arity T :=
match T with
| _ \/ _ \/ _ \/ _ \/ _ \/ _ \/ _ \/ _ => constr:(8)
| _ \/ _ \/ _ \/ _ \/ _ \/ _ \/ _ => constr:(7)
| _ \/ _ \/ _ \/ _ \/ _ \/ _ => constr:(6)
| _ \/ _ \/ _ \/ _ \/ _ => constr:(5)
| _ \/ _ \/ _ \/ _ => constr:(4)
| _ \/ _ \/ _ => constr:(3)
| _ \/ _ => constr:(2)
| _ -> ?T' => get_term_disjunction_arity T'
| _ => let P := get_head T in
       let T' := eval unfold P in T in
       match T' with
       | T => fail 1
       | _ => get_term_disjunction_arity T'
       end
end.

Ltac get_goal_disjunction_arity :=
match goal with |- ?T => get_term_disjunction_arity T end.

(** [branch N] applies to a goal of the form
  [P1 \/ ... \/ PK \/ ... \/ PN] and leaves the goal [PK].
  It only able to unfold the head definition (if there is one),
  but for more complex unfolding one should use the tactic
  [branch K of N]. *)

Tactic Notation "branch" constr(K) :=
let K := number_to_nat K in
unfold_goal_until_disjunction;
let N := get_goal_disjunction_arity in
branch_tactic K N.

(** [branch K of N] is similar to [branch K] except that the
  arity of the disjunction [N] is given manually, and so this
  version of the tactic is able to unfold definitions.
  In other words, applies to a goal of the form
  [P1 \/ ... \/ PK \/ ... \/ PN] and leaves the goal [PK]. *)

Tactic Notation "branch" constr(K) "of" constr(N) :=
let N := number_to_nat N in
let K := number_to_nat K in
branch_tactic K N.

(** N-ary Disjunction Deconstruction *)

(** Underlying implementation of [branches]. *)

Ltac destructs_disjunction_tactic N T :=
match N with
| 2 => destruct T as [? | ?]
| 3 => destruct T as [? | [? | ?]]
| 4 => destruct T as [? | [? | [? | ?]]]
| 5 => destruct T as [? | [? | [? | [? | ?]]]]
end.

(** [branches T] allows destructing a term [T] which is a N-ary
  disjunction. It is equivalent to [destruct T as [ H1 | .. | HN ] ],
  and produces [N] subgoals corresponding to the [N] possible cases. *)

Tactic Notation "branches" constr(T) :=
let TT := type of T in
let N := get_term_disjunction_arity TT in
destructs_disjunction_tactic N T.

(** [branches N T] is the same as [branches T] except that the arity is
  forced to [N]. This version is useful to unfold definitions
  on the fly. *)

Tactic Notation "branches" constr(N) constr(T) :=
let N := number_to_nat N in
destructs_disjunction_tactic N T.

(** [branches] automatically finds a hypothesis [h] that is a disjunction
  and destructs it. *)

Tactic Notation "branches" :=
match goal with h: _ \/ _ |- _ => branches h end.

(** N-ary Existentials *)

(* Underlying implementation of [exists]. *)

Ltac get_term_existential_arity T :=
match T with
| exists x1 x2 x3 x4 x5 x6 x7 x8, _ => constr:(8)
| exists x1 x2 x3 x4 x5 x6 x7, _ => constr:(7)
| exists x1 x2 x3 x4 x5 x6, _ => constr:(6)
| exists x1 x2 x3 x4 x5, _ => constr:(5)
| exists x1 x2 x3 x4, _ => constr:(4)
| exists x1 x2 x3, _ => constr:(3)
| exists x1 x2, _ => constr:(2)
| exists x1, _ => constr:(1)
| _ -> ?T' => get_term_existential_arity T'
| _ => let P := get_head T in
       let T' := eval unfold P in T in
       match T' with
       | T => fail 1
       | _ => get_term_existential_arity T'
       end
end.

Ltac get_goal_existential_arity :=
match goal with |- ?T => get_term_existential_arity T end.

(** [exists T1 ... TN] is a shorthand for [exists T1; ...; exists TN].
  It is intended to prove goals of the form [exist X1 .. XN, P].
  If an argument provided is [__] (double underscore), then an
  evar is introduced. [exists T1 .. TN ___] is equivalent to
  [exists T1 .. TN __ __ __] with as many [__] as possible. *)

Tactic Notation "exists_original" constr(T1) :=
exists T1.
Tactic Notation "exists" constr(T1) :=
match T1 with
| ltac_wild => esplit
| ltac_wilds => repeat esplit
| _ => exists T1
end.
Tactic Notation "exists" constr(T1) constr(T2) :=
exists T1; exists T2.
Tactic Notation "exists" constr(T1) constr(T2) constr(T3) :=
exists T1; exists T2; exists T3.
Tactic Notation "exists" constr(T1) constr(T2) constr(T3) constr(T4) :=
exists T1; exists T2; exists T3; exists T4.
Tactic Notation "exists" constr(T1) constr(T2) constr(T3) constr(T4)
constr(T5) :=
exists T1; exists T2; exists T3; exists T4; exists T5.
Tactic Notation "exists" constr(T1) constr(T2) constr(T3) constr(T4)
constr(T5) constr(T6) :=
exists T1; exists T2; exists T3; exists T4; exists T5; exists T6.

(** For compatibility with Coq syntax, [exists T1, .., TN] is also provided. *)

Tactic Notation "exists" constr(T1) "," constr(T2) :=
exists T1 T2.
Tactic Notation "exists" constr(T1) "," constr(T2) "," constr(T3) :=
exists T1 T2 T3.
Tactic Notation "exists" constr(T1) "," constr(T2) "," constr(T3) "," constr(T4) :=
exists T1 T2 T3 T4.
Tactic Notation "exists" constr(T1) "," constr(T2) "," constr(T3) "," constr(T4) ","
constr(T5) :=
exists T1 T2 T3 T4 T5.
Tactic Notation "exists" constr(T1) "," constr(T2) "," constr(T3) "," constr(T4) ","
constr(T5) "," constr(T6) :=
exists T1 T2 T3 T4 T5 T6.

(* The tactic [exists___ N] is short for [exists __ ... __]
 with [N] double-underscores. The tactic [exists] is equivalent
 to calling [exists___ N], where the value of [N] is obtained
 by counting the number of existentials syntactically present
 at the head of the goal. The behaviour of [exists] differs
 from that of [exists ___] is the case where the goal is a
 definition which yields an existential only after unfolding. *)

Tactic Notation "exists___" constr(N) :=
let rec aux N :=
  match N with
  | 0 => idtac
  | S ?N' => esplit; aux N'
  end in
let N := number_to_nat N in aux N.

(* --todo: deprecated *)
Tactic Notation "exists___" :=
let N := get_goal_existential_arity in
exists___ N.

(* --todo: does not seem to work *)
Tactic Notation "exists" :=
exists___.

(* --todo: [exists_all] is the new syntax for [exists___] *)
Tactic Notation "exists_all" := exists___.

(** Existentials and Conjunctions in Hypotheses *)

(** [unpack] or [unpack H] destructs conjunctions and existentials in
  all or one hypothesis. *)

Ltac unpack_core :=
repeat match goal with
| H: _ /\ _ |- _ => destruct H
| H: exists (varname: _), _ |- _ =>
    (* kludge to preserve the name of the quantified variable *)
    let name := fresh varname in
    destruct H as [name ?]
end.

Ltac unpack_hypothesis H :=
try match type of H with
| _ /\ _ =>
    let h1 := fresh "TEMP" in
    let h2 := fresh "TEMP" in
    destruct H as [ h1 h2 ];
    unpack_hypothesis h1;
    unpack_hypothesis h2
| exists (varname: _), _ =>
    (* kludge to preserve the name of the quantified variable *)
    let name := fresh varname in
    let body := fresh "TEMP" in
    destruct H as [name body];
    unpack_hypothesis body
end.

Tactic Notation "unpack" :=
unpack_core.
Tactic Notation "unpack" constr(H) :=
unpack_hypothesis H.

(* ################################################################# *)
(** * Tactics to Prove Typeclass Instances *)

(** [typeclass] is an automation tactic specialized for finding
  typeclass instances. *)

Tactic Notation "typeclass" :=
let go _ := eauto with typeclass_instances in
solve [ go tt | constructor; go tt ].

(** [solve_typeclass] is a simpler version of [typeclass], to use
  in hint tactics for resolving instances *)

Tactic Notation "solve_typeclass" :=
solve [ eauto with typeclass_instances ].

(* ################################################################# *)
(** * Tactics to Invoke Automation *)

(* ================================================================= *)
(** ** Definitions for Parsing Compatibility *)

Tactic Notation "f_equal" :=
f_equal.
Tactic Notation "constructor" :=
constructor.
Tactic Notation "simple" :=
simpl.

Tactic Notation "split" :=
split.

Tactic Notation "right" :=
right.
Tactic Notation "left" :=
left.

(* ================================================================= *)
(** ** [hint] to Add Hints Local to a Lemma *)

(** [hint E] adds [E] as an hypothesis so that automation can use it.
  Syntax [hint E1,..,EN] is available *)

Tactic Notation "hint" constr(E) :=
let H := fresh "Hint" in lets H: E.
Tactic Notation "hint" constr(E1) "," constr(E2) :=
hint E1; hint E2.
Tactic Notation "hint" constr(E1) "," constr(E2) "," constr(E3) :=
hint E1; hint E2; hint(E3).
Tactic Notation "hint" constr(E1) "," constr(E2) "," constr(E3) "," constr(E4) :=
hint E1; hint E2; hint(E3); hint(E4 ).

(* ================================================================= *)
(** ** [jauto], a New Automation Tactic *)

(** [jauto] is better at [intuition eauto] because it can open existentials
  from the context. In the same time, [jauto] can be faster than
  [intuition eauto] because it does not destruct disjunctions from the
  context. The strategy of [jauto] can be summarized as follows:
  - open all the existentials and conjunctions from the context
  - call esplit and split on the existentials and conjunctions in the goal
  - call eauto. *)

Tactic Notation "jauto" :=
try solve [ jauto_set; eauto ].

Tactic Notation "jauto_fast" :=
try solve [ auto | eauto | jauto ].

(** [iauto] is a shorthand for [intuition eauto] *)

Tactic Notation "iauto" := try solve [intuition eauto].

(* ================================================================= *)
(** ** Definitions of Automation Tactics *)

(** The two following tactics defined the default behaviour of
  "light automation" and "strong automation". These tactics
  may be redefined at any time using the syntax [Ltac .. ::= ..]. *)

(** [auto_tilde] is the tactic which will be called each time a symbol
  [~] is used after a tactic. *)

Ltac auto_tilde_default := auto.
Ltac auto_tilde := auto_tilde_default.

(** [auto_star] is the tactic which will be called each time a symbol
  [*] is used after a tactic. *)

Ltac auto_star_default := try solve [ auto | eauto | intuition eauto ].
(* --todo: should be jauto *)
Ltac auto_star := try solve [ jauto ]. (* SPECIAL VERSION FOR SF *)

(** [autos~] is a notation for tactic [auto_tilde]. It may be followed
  by lemmas (or proofs terms) which auto will be able to use
  for solving the goal.

  [autos] is an alias for [autos~] *)

Tactic Notation "autos" :=
auto_tilde.
Tactic Notation "autos" "~" :=
auto_tilde.
Tactic Notation "autos" "~" constr(E1) :=
lets: E1; auto_tilde.
Tactic Notation "autos" "~" constr(E1) constr(E2) :=
lets: E1; autos~ E2.
Tactic Notation "autos" "~" constr(E1) constr(E2) constr(E3) :=
lets: E1; autos~ E2 E3.
Tactic Notation "autos" "~" constr(E1) constr(E2) constr(E3) constr(E4) :=
lets: E1; autos~ E2 E3 E4.
Tactic Notation "autos" "~" constr(E1) constr(E2) constr(E3) constr(E4)
constr(E5):=
lets: E1; autos~ E2 E3 E4 E5.

(* New syntax using coma *)
Tactic Notation "autos" :=
auto_tilde.
Tactic Notation "autos" "~" :=
auto_tilde.
Tactic Notation "autos" "~" constr(E1) :=
lets: E1; auto_tilde.
Tactic Notation "autos" "~" constr(E1) "," constr(E2) :=
lets: E1; autos~ E2.
Tactic Notation "autos" "~" constr(E1) "," constr(E2) "," constr(E3) :=
lets: E1; autos~ E2 E3.
Tactic Notation "autos" "~" constr(E1) "," constr(E2) "," constr(E3) "," constr(E4) :=
lets: E1; autos~ E2 E3 E4.
Tactic Notation "autos" "~" constr(E1) "," constr(E2) "," constr(E3) "," constr(E4) ","
constr(E5):=
lets: E1; autos~ E2 E3 E4 E5.

(** [autos*] is a notation for tactic [auto_star]. It may be followed
  by lemmas (or proofs terms) which auto will be able to use
  for solving the goal. *)

Tactic Notation "autos" "*" :=
auto_star.
Tactic Notation "autos" "*" constr(E1) :=
lets: E1; auto_star.
Tactic Notation "autos" "*" constr(E1) constr(E2) :=
lets: E1; autos* E2.
Tactic Notation "autos" "*" constr(E1) constr(E2) constr(E3) :=
lets: E1; autos* E2 E3.
Tactic Notation "autos" "*" constr(E1) constr(E2) constr(E3) constr(E4) :=
lets: E1; autos* E2 E3 E4.
Tactic Notation "autos" "*" constr(E1) constr(E2) constr(E3) constr(E4)
constr(E5):=
lets: E1; autos* E2 E3 E4 E5.

(* New syntax using coma *)

Tactic Notation "autos" "*" :=
auto_star.
Tactic Notation "autos" "*" constr(E1) :=
lets: E1; auto_star.
Tactic Notation "autos" "*" constr(E1) "," constr(E2) :=
lets: E1; autos* E2.
Tactic Notation "autos" "*" constr(E1) "," constr(E2) "," constr(E3) :=
lets: E1; autos* E2 E3.
Tactic Notation "autos" "*" constr(E1) "," constr(E2) "," constr(E3) "," constr(E4) :=
lets: E1; autos* E2 E3 E4.
Tactic Notation "autos" "*" constr(E1) "," constr(E2) "," constr(E3) "," constr(E4) ","
constr(E5):=
lets: E1; autos* E2 E3 E4 E5.

(** [auto_false] is a version of [auto] able to spot some contradictions.
  There is an ad-hoc support for goals in [<->]: split is called first.
  [auto_false~] and [auto_false*] are also available. *)

Ltac auto_false_base cont :=
try solve [
  intros_all; try match goal with |- _ <-> _ => split end;
  solve [ cont tt | intros_all; false; cont tt ] ].

Tactic Notation "auto_false" :=
 auto_false_base ltac:(fun tt => auto).
Tactic Notation "auto_false" "~" :=
 auto_false_base ltac:(fun tt => auto_tilde).
Tactic Notation "auto_false" "*" :=
 auto_false_base ltac:(fun tt => auto_star).

Tactic Notation "dauto" :=
dintuition eauto.

(* ================================================================= *)
(** ** Parsing for Light Automation *)

(** Any tactic followed by the symbol [~] will have [auto_tilde] called
  on all of its subgoals. Three exceptions:
  - [cuts] and [asserts] only call [auto] on their first subgoal,
  - [apply~] relies on [sapply] rather than [apply],
  - [tryfalse~] is defined as [tryfalse by auto_tilde].

 Some builtin tactics are not defined using tactic notations
 and thus cannot be extended, e.g., [simpl] and [unfold].
 For these, notation such as [simpl~] will not be available. *)

Tactic Notation "equates" "~" constr(E) :=
 equates E; auto_tilde.
Tactic Notation "equates" "~" constr(n1) constr(n2) :=
equates n1 n2; auto_tilde.
Tactic Notation "equates" "~" constr(n1) constr(n2) constr(n3) :=
equates n1 n2 n3; auto_tilde.
Tactic Notation "equates" "~" constr(n1) constr(n2) constr(n3) constr(n4) :=
equates n1 n2 n3 n4; auto_tilde.

Tactic Notation "applys_eq" "~" constr(H) :=
applys_eq H; auto_tilde.
Tactic Notation "applys_eq" "~" constr(H) constr(E) :=
applys_eq H E; auto_tilde.
Tactic Notation "applys_eq" "~" constr(H) constr(n1) constr(n2) :=
applys_eq H n1 n2; auto_tilde.
Tactic Notation "applys_eq" "~" constr(H) constr(n1) constr(n2) constr(n3) :=
applys_eq H n1 n2 n3; auto_tilde.
Tactic Notation "applys_eq" "~" constr(H) constr(n1) constr(n2) constr(n3) constr(n4) :=
applys_eq H n1 n2 n3 n4; auto_tilde.

Tactic Notation "apply" "~" constr(H) :=
sapply H; auto_tilde.

Tactic Notation "destruct" "~" constr(H) :=
destruct H; auto_tilde.
Tactic Notation "destruct" "~" constr(H) "as" simple_intropattern(I) :=
destruct H as I; auto_tilde.
Tactic Notation "f_equal" "~" :=
f_equal; auto_tilde.
Tactic Notation "induction" "~" constr(H) :=
induction H; auto_tilde.
Tactic Notation "inversion" "~" constr(H) :=
inversion H; auto_tilde.
Tactic Notation "split" "~" :=
split; auto_tilde.
Tactic Notation "subst" "~" :=
subst; auto_tilde.
Tactic Notation "right" "~" :=
right; auto_tilde.
Tactic Notation "left" "~" :=
left; auto_tilde.
Tactic Notation "constructor" "~" :=
constructor; auto_tilde.
Tactic Notation "constructors" "~" :=
constructors; auto_tilde.

Tactic Notation "false" "~" :=
false; auto_tilde.
Tactic Notation "false" "~" constr(E) :=
false_then E ltac:(fun _ => auto_tilde).
Tactic Notation "false" "~" constr(E0) constr(E1) :=
false~ (>> E0 E1).
Tactic Notation "false" "~" constr(E0) constr(E1) constr(E2) :=
false~ (>> E0 E1 E2).
Tactic Notation "false" "~" constr(E0) constr(E1) constr(E2) constr(E3) :=
false~ (>> E0 E1 E2 E3).
Tactic Notation "false" "~" constr(E0) constr(E1) constr(E2) constr(E3) constr(E4) :=
false~ (>> E0 E1 E2 E3 E4).
Tactic Notation "tryfalse" "~" :=
try solve [ false~ ].

Tactic Notation "asserts" "~" simple_intropattern(H) ":" constr(E) :=
asserts H: E; [ auto_tilde | idtac ].
Tactic Notation "asserts" "~" ":" constr(E) :=
let H := fresh "H" in asserts~ H: E.
Tactic Notation "cuts" "~" simple_intropattern(H) ":" constr(E) :=
cuts H: E; [ auto_tilde | idtac ].
Tactic Notation "cuts" "~" ":" constr(E) :=
cuts: E; [ auto_tilde | idtac ].

Tactic Notation "lets" "~" simple_intropattern(I) ":" constr(E) :=
lets I: E; auto_tilde.
Tactic Notation "lets" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) :=
lets I: E0 A1; auto_tilde.
Tactic Notation "lets" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) :=
lets I: E0 A1 A2; auto_tilde.
Tactic Notation "lets" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
lets I: E0 A1 A2 A3; auto_tilde.
Tactic Notation "lets" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
lets I: E0 A1 A2 A3 A4; auto_tilde.
Tactic Notation "lets" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
lets I: E0 A1 A2 A3 A4 A5; auto_tilde.

Tactic Notation "lets" "~" ":" constr(E) :=
lets: E; auto_tilde.
Tactic Notation "lets" "~" ":" constr(E0)
constr(A1) :=
lets: E0 A1; auto_tilde.
Tactic Notation "lets" "~" ":" constr(E0)
constr(A1) constr(A2) :=
lets: E0 A1 A2; auto_tilde.
Tactic Notation "lets" "~" ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
lets: E0 A1 A2 A3; auto_tilde.
Tactic Notation "lets" "~" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
lets: E0 A1 A2 A3 A4; auto_tilde.
Tactic Notation "lets" "~" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
lets: E0 A1 A2 A3 A4 A5; auto_tilde.

Tactic Notation "forwards" "~" simple_intropattern(I) ":" constr(E) :=
forwards I: E; auto_tilde.
Tactic Notation "forwards" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) :=
forwards I: E0 A1; auto_tilde.
Tactic Notation "forwards" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) :=
forwards I: E0 A1 A2; auto_tilde.
Tactic Notation "forwards" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
forwards I: E0 A1 A2 A3; auto_tilde.
Tactic Notation "forwards" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
forwards I: E0 A1 A2 A3 A4; auto_tilde.
Tactic Notation "forwards" "~" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
forwards I: E0 A1 A2 A3 A4 A5; auto_tilde.

Tactic Notation "forwards" "~" ":" constr(E) :=
forwards: E; auto_tilde.
Tactic Notation "forwards" "~" ":" constr(E0)
constr(A1) :=
forwards: E0 A1; auto_tilde.
Tactic Notation "forwards" "~" ":" constr(E0)
constr(A1) constr(A2) :=
forwards: E0 A1 A2; auto_tilde.
Tactic Notation "forwards" "~" ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
forwards: E0 A1 A2 A3; auto_tilde.
Tactic Notation "forwards" "~" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
forwards: E0 A1 A2 A3 A4; auto_tilde.
Tactic Notation "forwards" "~" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
forwards: E0 A1 A2 A3 A4 A5; auto_tilde.

Tactic Notation "applys" "~" constr(H) :=
sapply H; auto_tilde. (*todo?*)
Tactic Notation "applys" "~" constr(E0) constr(A1) :=
applys E0 A1; auto_tilde.
Tactic Notation "applys" "~" constr(E0) constr(A1) :=
applys E0 A1; auto_tilde.
Tactic Notation "applys" "~" constr(E0) constr(A1) constr(A2) :=
applys E0 A1 A2; auto_tilde.
Tactic Notation "applys" "~" constr(E0) constr(A1) constr(A2) constr(A3) :=
applys E0 A1 A2 A3; auto_tilde.
Tactic Notation "applys" "~" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) :=
applys E0 A1 A2 A3 A4; auto_tilde.
Tactic Notation "applys" "~" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
applys E0 A1 A2 A3 A4 A5; auto_tilde.

Tactic Notation "specializes" "~" hyp(H) :=
specializes H; auto_tilde.
Tactic Notation "specializes" "~" hyp(H) constr(A1) :=
specializes H A1; auto_tilde.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) :=
specializes H A1 A2; auto_tilde.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) :=
specializes H A1 A2 A3; auto_tilde.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) constr(A4) :=
specializes H A1 A2 A3 A4; auto_tilde.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
specializes H A1 A2 A3 A4 A5; auto_tilde.

Tactic Notation "fapply" "~" constr(E) :=
fapply E; auto_tilde.
Tactic Notation "sapply" "~" constr(E) :=
sapply E; auto_tilde.

Tactic Notation "logic" "~" constr(E) :=
logic_base E ltac:(fun _ => auto_tilde).

Tactic Notation "intros_all" "~" :=
intros_all; auto_tilde.

Tactic Notation "unfolds" "~" :=
unfolds; auto_tilde.
Tactic Notation "unfolds" "~" constr(F1) :=
unfolds F1; auto_tilde.
Tactic Notation "unfolds" "~" constr(F1) "," constr(F2) :=
unfolds F1, F2; auto_tilde.
Tactic Notation "unfolds" "~" constr(F1) "," constr(F2) "," constr(F3) :=
unfolds F1, F2, F3; auto_tilde.
Tactic Notation "unfolds" "~" constr(F1) "," constr(F2) "," constr(F3) ","
constr(F4) :=
unfolds F1, F2, F3, F4; auto_tilde.

Tactic Notation "simple" "~" :=
simpl; auto_tilde.
Tactic Notation "simple" "~" "in" hyp(H) :=
simpl in H; auto_tilde.
Tactic Notation "simpls" "~" :=
simpls; auto_tilde.
Tactic Notation "hnfs" "~" :=
hnfs; auto_tilde.
Tactic Notation "hnfs" "~" "in" hyp(H) :=
hnf in H; auto_tilde.
Tactic Notation "substs" "~" :=
substs; auto_tilde.
Tactic Notation "intro_hyp" "~" hyp(H) :=
subst_hyp H; auto_tilde.
Tactic Notation "intro_subst" "~" :=
intro_subst; auto_tilde.
Tactic Notation "subst_eq" "~" constr(E) :=
subst_eq E; auto_tilde.

Tactic Notation "rewrite" "~" constr(E) :=
rewrite E; auto_tilde.
Tactic Notation "rewrite" "~" "<-" constr(E) :=
rewrite <- E; auto_tilde.
Tactic Notation "rewrite" "~" constr(E) "in" hyp(H) :=
rewrite E in H; auto_tilde.
Tactic Notation "rewrite" "~" "<-" constr(E) "in" hyp(H) :=
rewrite <- E in H; auto_tilde.

Tactic Notation "rewrites" "~" constr(E) :=
rewrites E; auto_tilde.
Tactic Notation "rewrites" "~" constr(E) "in" hyp(H) :=
rewrites E in H; auto_tilde.
Tactic Notation "rewrites" "~" constr(E) "in" "*" :=
rewrites E in *; auto_tilde.
Tactic Notation "rewrites" "~" "<-" constr(E) :=
rewrites <- E; auto_tilde.
Tactic Notation "rewrites" "~" "<-" constr(E) "in" hyp(H) :=
rewrites <- E in H; auto_tilde.
Tactic Notation "rewrites" "~" "<-" constr(E) "in" "*" :=
rewrites <- E in *; auto_tilde.

Tactic Notation "rewrite_all" "~" constr(E) :=
rewrite_all E; auto_tilde.
Tactic Notation "rewrite_all" "~" "<-" constr(E) :=
rewrite_all <- E; auto_tilde.
Tactic Notation "rewrite_all" "~" constr(E) "in" ident(H) :=
rewrite_all E in H; auto_tilde.
Tactic Notation "rewrite_all" "~" "<-" constr(E) "in" ident(H) :=
rewrite_all <- E in H; auto_tilde.
Tactic Notation "rewrite_all" "~" constr(E) "in" "*" :=
rewrite_all E in *; auto_tilde.
Tactic Notation "rewrite_all" "~" "<-" constr(E) "in" "*" :=
rewrite_all <- E in *; auto_tilde.

Tactic Notation "asserts_rewrite" "~" constr(E) :=
asserts_rewrite E; auto_tilde.
Tactic Notation "asserts_rewrite" "~" "<-" constr(E) :=
asserts_rewrite <- E; auto_tilde.
Tactic Notation "asserts_rewrite" "~" constr(E) "in" hyp(H) :=
asserts_rewrite E in H; auto_tilde.
Tactic Notation "asserts_rewrite" "~" "<-" constr(E) "in" hyp(H) :=
asserts_rewrite <- E in H; auto_tilde.
Tactic Notation "asserts_rewrite" "~" constr(E) "in" "*" :=
asserts_rewrite E in *; auto_tilde.
Tactic Notation "asserts_rewrite" "~" "<-" constr(E) "in" "*" :=
asserts_rewrite <- E in *; auto_tilde.

Tactic Notation "cuts_rewrite" "~" constr(E) :=
cuts_rewrite E; auto_tilde.
Tactic Notation "cuts_rewrite" "~" "<-" constr(E) :=
cuts_rewrite <- E; auto_tilde.
Tactic Notation "cuts_rewrite" "~" constr(E) "in" hyp(H) :=
cuts_rewrite E in H; auto_tilde.
Tactic Notation "cuts_rewrite" "~" "<-" constr(E) "in" hyp(H) :=
cuts_rewrite <- E in H; auto_tilde.

Tactic Notation "erewrite" "~" constr(E) :=
erewrite E; auto_tilde.
Tactic Notation "erewrites" "~" constr(E) :=
erewrites E; auto_tilde.

Tactic Notation "fequal" "~" :=
fequal; auto_tilde.
Tactic Notation "fequals" "~" :=
fequals; auto_tilde.
Tactic Notation "pi_rewrite" "~" constr(E) :=
pi_rewrite E; auto_tilde.
Tactic Notation "pi_rewrite" "~" constr(E) "in" hyp(H) :=
pi_rewrite E in H; auto_tilde.

Tactic Notation "invert" "~" hyp(H) :=
invert H; auto_tilde.
Tactic Notation "inverts" "~" hyp(H) :=
inverts H; auto_tilde.
Tactic Notation "inverts" "~" hyp(E) "as" :=
inverts E as; auto_tilde.
Tactic Notation "injects" "~" hyp(H) :=
injects H; auto_tilde.
Tactic Notation "inversions" "~" hyp(H) :=
inversions H; auto_tilde.

Tactic Notation "cases" "~" constr(E) "as" ident(H) :=
cases E as H; auto_tilde.
Tactic Notation "cases" "~" constr(E) :=
cases E; auto_tilde.
Tactic Notation "case_if" "~" :=
case_if; auto_tilde.
Tactic Notation "case_ifs" "~" :=
case_ifs; auto_tilde.
Tactic Notation "case_if" "~" "in" hyp(H) :=
case_if in H; auto_tilde.
Tactic Notation "cases_if" "~" :=
cases_if; auto_tilde.
Tactic Notation "cases_if" "~" "in" hyp(H) :=
cases_if in H; auto_tilde.
Tactic Notation "destruct_if" "~" :=
destruct_if; auto_tilde.
Tactic Notation "destruct_if" "~" "in" hyp(H) :=
destruct_if in H; auto_tilde.

Tactic Notation "cases'" "~" constr(E) "as" ident(H) :=
cases' E as H; auto_tilde.
Tactic Notation "cases'" "~" constr(E) :=
cases' E; auto_tilde.
Tactic Notation "cases_if'" "~" "as" ident(H) :=
cases_if' as H; auto_tilde.
Tactic Notation "cases_if'" "~" :=
cases_if'; auto_tilde.

Tactic Notation "decides_equality" "~" :=
decides_equality; auto_tilde.

Tactic Notation "iff" "~" :=
iff; auto_tilde.
Tactic Notation "iff" "~" simple_intropattern(I) :=
iff I; auto_tilde.
Tactic Notation "splits" "~" :=
splits; auto_tilde.
Tactic Notation "splits" "~" constr(N) :=
splits N; auto_tilde.

Tactic Notation "destructs" "~" constr(T) :=
destructs T; auto_tilde.
Tactic Notation "destructs" "~" constr(N) constr(T) :=
destructs N T; auto_tilde.

Tactic Notation "branch" "~" constr(N) :=
branch N; auto_tilde.
Tactic Notation "branch" "~" constr(K) "of" constr(N) :=
branch K of N; auto_tilde.

Tactic Notation "branches" "~" :=
branches; auto_tilde.
Tactic Notation "branches" "~" constr(T) :=
branches T; auto_tilde.
Tactic Notation "branches" "~" constr(N) constr(T) :=
branches N T; auto_tilde.

Tactic Notation "exists" "~" :=
exists; auto_tilde.
Tactic Notation "exists___" "~" :=
exists___; auto_tilde.
Tactic Notation "exists" "~" constr(T1) :=
exists T1; auto_tilde.
Tactic Notation "exists" "~" constr(T1) constr(T2) :=
exists T1 T2; auto_tilde.
Tactic Notation "exists" "~" constr(T1) constr(T2) constr(T3) :=
exists T1 T2 T3; auto_tilde.
Tactic Notation "exists" "~" constr(T1) constr(T2) constr(T3) constr(T4) :=
exists T1 T2 T3 T4; auto_tilde.
Tactic Notation "exists" "~" constr(T1) constr(T2) constr(T3) constr(T4)
constr(T5) :=
exists T1 T2 T3 T4 T5; auto_tilde.
Tactic Notation "exists" "~" constr(T1) constr(T2) constr(T3) constr(T4)
constr(T5) constr(T6) :=
exists T1 T2 T3 T4 T5 T6; auto_tilde.

Tactic Notation "exists" "~" constr(T1) "," constr(T2) :=
exists T1 T2; auto_tilde.
Tactic Notation "exists" "~" constr(T1) "," constr(T2) "," constr(T3) :=
exists T1 T2 T3; auto_tilde.
Tactic Notation "exists" "~" constr(T1) "," constr(T2) "," constr(T3) ","
constr(T4) :=
exists T1 T2 T3 T4; auto_tilde.
Tactic Notation "exists" "~" constr(T1) "," constr(T2) "," constr(T3) ","
constr(T4) "," constr(T5) :=
exists T1 T2 T3 T4 T5; auto_tilde.
Tactic Notation "exists" "~" constr(T1) "," constr(T2) "," constr(T3) ","
constr(T4) "," constr(T5) "," constr(T6) :=
exists T1 T2 T3 T4 T5 T6; auto_tilde.

(* ================================================================= *)
(** ** Parsing for Strong Automation *)

(** Any tactic followed by the symbol [*] will have [auto*] called
  on all of its subgoals. The exceptions to these rules are the
  same as for light automation.

  Exception: use [subs*] instead of [subst*] if you
  import the library [Coq.Classes.Equivalence]. *)

Tactic Notation "equates" "*" constr(E) :=
 equates E; auto_star.
Tactic Notation "equates" "*" constr(n1) constr(n2) :=
equates n1 n2; auto_star.
Tactic Notation "equates" "*" constr(n1) constr(n2) constr(n3) :=
equates n1 n2 n3; auto_star.
Tactic Notation "equates" "*" constr(n1) constr(n2) constr(n3) constr(n4) :=
equates n1 n2 n3 n4; auto_star.

Tactic Notation "applys_eq" "*" constr(H) :=
applys_eq H; auto_star.
Tactic Notation "applys_eq" "*" constr(H) constr(E) :=
applys_eq H E; auto_star.
Tactic Notation "applys_eq" "*" constr(H) constr(n1) constr(n2) :=
applys_eq H n1 n2; auto_star.
Tactic Notation "applys_eq" "*" constr(H) constr(n1) constr(n2) constr(n3) :=
applys_eq H n1 n2 n3; auto_star.
Tactic Notation "applys_eq" "*" constr(H) constr(n1) constr(n2) constr(n3) constr(n4) :=
applys_eq H n1 n2 n3 n4; auto_star.

Tactic Notation "apply" "*" constr(H) :=
sapply H; auto_star.

Tactic Notation "destruct" "*" constr(H) :=
destruct H; auto_star.
Tactic Notation "destruct" "*" constr(H) "as" simple_intropattern(I) :=
destruct H as I; auto_star.
Tactic Notation "f_equal" "*" :=
f_equal; auto_star.
Tactic Notation "induction" "*" constr(H) :=
induction H; auto_star.
Tactic Notation "inversion" "*" constr(H) :=
inversion H; auto_star.
Tactic Notation "split" "*" :=
split; auto_star.
Tactic Notation "subs" "*" :=
subst; auto_star.
Tactic Notation "subst" "*" :=
subst; auto_star.
Tactic Notation "right" "*" :=
right; auto_star.
Tactic Notation "left" "*" :=
left; auto_star.
Tactic Notation "constructor" "*" :=
constructor; auto_star.
Tactic Notation "constructors" "*" :=
constructors; auto_star.

Tactic Notation "false" "*" :=
false; auto_star.
Tactic Notation "false" "*" constr(E) :=
false_then E ltac:(fun _ => auto_star).
Tactic Notation "false" "*" constr(E0) constr(E1) :=
false* (>> E0 E1).
Tactic Notation "false" "*" constr(E0) constr(E1) constr(E2) :=
false* (>> E0 E1 E2).
Tactic Notation "false" "*" constr(E0) constr(E1) constr(E2) constr(E3) :=
false* (>> E0 E1 E2 E3).
Tactic Notation "false" "*" constr(E0) constr(E1) constr(E2) constr(E3) constr(E4) :=
false* (>> E0 E1 E2 E3 E4).
Tactic Notation "tryfalse" "*" :=
try solve [ false* ].

Tactic Notation "asserts" "*" simple_intropattern(H) ":" constr(E) :=
asserts H: E; [ auto_star | idtac ].
Tactic Notation "asserts" "*" ":" constr(E) :=
let H := fresh "H" in asserts* H: E.
Tactic Notation "cuts" "*" simple_intropattern(H) ":" constr(E) :=
cuts H: E; [ auto_star | idtac ].
Tactic Notation "cuts" "*" ":" constr(E) :=
cuts: E; [ auto_star | idtac ].

Tactic Notation "lets" "*" simple_intropattern(I) ":" constr(E) :=
lets I: E; auto_star.
Tactic Notation "lets" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) :=
lets I: E0 A1; auto_star.
Tactic Notation "lets" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) :=
lets I: E0 A1 A2; auto_star.
Tactic Notation "lets" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
lets I: E0 A1 A2 A3; auto_star.
Tactic Notation "lets" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
lets I: E0 A1 A2 A3 A4; auto_star.
Tactic Notation "lets" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
lets I: E0 A1 A2 A3 A4 A5; auto_star.

Tactic Notation "lets" "*" ":" constr(E) :=
lets: E; auto_star.
Tactic Notation "lets" "*" ":" constr(E0)
constr(A1) :=
lets: E0 A1; auto_star.
Tactic Notation "lets" "*" ":" constr(E0)
constr(A1) constr(A2) :=
lets: E0 A1 A2; auto_star.
Tactic Notation "lets" "*" ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
lets: E0 A1 A2 A3; auto_star.
Tactic Notation "lets" "*" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
lets: E0 A1 A2 A3 A4; auto_star.
Tactic Notation "lets" "*" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
lets: E0 A1 A2 A3 A4 A5; auto_star.

Tactic Notation "forwards" "*" simple_intropattern(I) ":" constr(E) :=
forwards I: E; auto_star.
Tactic Notation "forwards" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) :=
forwards I: E0 A1; auto_star.
Tactic Notation "forwards" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) :=
forwards I: E0 A1 A2; auto_star.
Tactic Notation "forwards" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
forwards I: E0 A1 A2 A3; auto_star.
Tactic Notation "forwards" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
forwards I: E0 A1 A2 A3 A4; auto_star.
Tactic Notation "forwards" "*" simple_intropattern(I) ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
forwards I: E0 A1 A2 A3 A4 A5; auto_star.

Tactic Notation "forwards" "*" ":" constr(E) :=
forwards: E; auto_star.
Tactic Notation "forwards" "*" ":" constr(E0)
constr(A1) :=
forwards: E0 A1; auto_star.
Tactic Notation "forwards" "*" ":" constr(E0)
constr(A1) constr(A2) :=
forwards: E0 A1 A2; auto_star.
Tactic Notation "forwards" "*" ":" constr(E0)
constr(A1) constr(A2) constr(A3) :=
forwards: E0 A1 A2 A3; auto_star.
Tactic Notation "forwards" "*" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) :=
forwards: E0 A1 A2 A3 A4; auto_star.
Tactic Notation "forwards" "*" ":" constr(E0)
constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
forwards: E0 A1 A2 A3 A4 A5; auto_star.

Tactic Notation "applys" "*" constr(H) :=
sapply H; auto_star. (*todo?*)
Tactic Notation "applys" "*" constr(E0) constr(A1) :=
applys E0 A1; auto_star.
Tactic Notation "applys" "*" constr(E0) constr(A1) :=
applys E0 A1; auto_star.
Tactic Notation "applys" "*" constr(E0) constr(A1) constr(A2) :=
applys E0 A1 A2; auto_star.
Tactic Notation "applys" "*" constr(E0) constr(A1) constr(A2) constr(A3) :=
applys E0 A1 A2 A3; auto_star.
Tactic Notation "applys" "*" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) :=
applys E0 A1 A2 A3 A4; auto_star.
Tactic Notation "applys" "*" constr(E0) constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
applys E0 A1 A2 A3 A4 A5; auto_star.

Tactic Notation "specializes" "*" hyp(H) :=
specializes H; auto_star.
Tactic Notation "specializes" "~" hyp(H) constr(A1) :=
specializes H A1; auto_star.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) :=
specializes H A1 A2; auto_star.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) :=
specializes H A1 A2 A3; auto_star.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) constr(A4) :=
specializes H A1 A2 A3 A4; auto_star.
Tactic Notation "specializes" hyp(H) constr(A1) constr(A2) constr(A3) constr(A4) constr(A5) :=
specializes H A1 A2 A3 A4 A5; auto_star.

Tactic Notation "fapply" "*" constr(E) :=
fapply E; auto_star.
Tactic Notation "sapply" "*" constr(E) :=
sapply E; auto_star.

Tactic Notation "logic" constr(E) :=
logic_base E ltac:(fun _ => auto_star).

Tactic Notation "intros_all" "*" :=
intros_all; auto_star.

Tactic Notation "unfolds" "*" :=
unfolds; auto_star.
Tactic Notation "unfolds" "*" constr(F1) :=
unfolds F1; auto_star.
Tactic Notation "unfolds" "*" constr(F1) "," constr(F2) :=
unfolds F1, F2; auto_star.
Tactic Notation "unfolds" "*" constr(F1) "," constr(F2) "," constr(F3) :=
unfolds F1, F2, F3; auto_star.
Tactic Notation "unfolds" "*" constr(F1) "," constr(F2) "," constr(F3) ","
constr(F4) :=
unfolds F1, F2, F3, F4; auto_star.

Tactic Notation "simple" "*" :=
simpl; auto_star.
Tactic Notation "simple" "*" "in" hyp(H) :=
simpl in H; auto_star.
Tactic Notation "simpls" "*" :=
simpls; auto_star.
Tactic Notation "hnfs" "*" :=
hnfs; auto_star.
Tactic Notation "hnfs" "*" "in" hyp(H) :=
hnf in H; auto_star.
Tactic Notation "substs" "*" :=
substs; auto_star.
Tactic Notation "intro_hyp" "*" hyp(H) :=
subst_hyp H; auto_star.
Tactic Notation "intro_subst" "*" :=
intro_subst; auto_star.
Tactic Notation "subst_eq" "*" constr(E) :=
subst_eq E; auto_star.

Tactic Notation "rewrite" "*" constr(E) :=
rewrite E; auto_star.
Tactic Notation "rewrite" "*" "<-" constr(E) :=
rewrite <- E; auto_star.
Tactic Notation "rewrite" "*" constr(E) "in" hyp(H) :=
rewrite E in H; auto_star.
Tactic Notation "rewrite" "*" "<-" constr(E) "in" hyp(H) :=
rewrite <- E in H; auto_star.

Tactic Notation "rewrites" "*" constr(E) :=
rewrites E; auto_star.
Tactic Notation "rewrites" "*" constr(E) "in" hyp(H):=
rewrites E in H; auto_star.
Tactic Notation "rewrites" "*" constr(E) "in" "*":=
rewrites E in *; auto_star.
Tactic Notation "rewrites" "*" "<-" constr(E) :=
rewrites <- E; auto_star.
Tactic Notation "rewrites" "*" "<-" constr(E) "in" hyp(H):=
rewrites <- E in H; auto_star.
Tactic Notation "rewrites" "*" "<-" constr(E) "in" "*":=
rewrites <- E in *; auto_star.

Tactic Notation "rewrite_all" "*" constr(E) :=
rewrite_all E; auto_star.
Tactic Notation "rewrite_all" "*" "<-" constr(E) :=
rewrite_all <- E; auto_star.
Tactic Notation "rewrite_all" "*" constr(E) "in" ident(H) :=
rewrite_all E in H; auto_star.
Tactic Notation "rewrite_all" "*" "<-" constr(E) "in" ident(H) :=
rewrite_all <- E in H; auto_star.
Tactic Notation "rewrite_all" "*" constr(E) "in" "*" :=
rewrite_all E in *; auto_star.
Tactic Notation "rewrite_all" "*" "<-" constr(E) "in" "*" :=
rewrite_all <- E in *; auto_star.

Tactic Notation "asserts_rewrite" "*" constr(E) :=
asserts_rewrite E; auto_star.
Tactic Notation "asserts_rewrite" "*" "<-" constr(E) :=
asserts_rewrite <- E; auto_star.
Tactic Notation "asserts_rewrite" "*" constr(E) "in" hyp(H) :=
asserts_rewrite E; auto_star.
Tactic Notation "asserts_rewrite" "*" "<-" constr(E) "in" hyp(H) :=
asserts_rewrite <- E; auto_star.
Tactic Notation "asserts_rewrite" "*" constr(E) "in" "*" :=
asserts_rewrite E in *; auto_tilde.
Tactic Notation "asserts_rewrite" "*" "<-" constr(E) "in" "*" :=
asserts_rewrite <- E in *; auto_tilde.

Tactic Notation "cuts_rewrite" "*" constr(E) :=
cuts_rewrite E; auto_star.
Tactic Notation "cuts_rewrite" "*" "<-" constr(E) :=
cuts_rewrite <- E; auto_star.
Tactic Notation "cuts_rewrite" "*" constr(E) "in" hyp(H) :=
cuts_rewrite E in H; auto_star.
Tactic Notation "cuts_rewrite" "*" "<-" constr(E) "in" hyp(H) :=
cuts_rewrite <- E in H; auto_star.

Tactic Notation "erewrite" "*" constr(E) :=
erewrite E; auto_star.
Tactic Notation "erewrites" "*" constr(E) :=
erewrites E; auto_star.

Tactic Notation "fequal" "*" :=
fequal; auto_star.
Tactic Notation "fequals" "*" :=
fequals; auto_star.
Tactic Notation "pi_rewrite" "*" constr(E) :=
pi_rewrite E; auto_star.
Tactic Notation "pi_rewrite" "*" constr(E) "in" hyp(H) :=
pi_rewrite E in H; auto_star.

Tactic Notation "invert" "*" hyp(H) :=
invert H; auto_star.
Tactic Notation "inverts" "*" hyp(H) :=
inverts H; auto_star.
Tactic Notation "inverts" "*" hyp(E) "as" :=
inverts E as; auto_star.
Tactic Notation "injects" "*" hyp(H) :=
injects H; auto_star.
Tactic Notation "inversions" "*" hyp(H) :=
inversions H; auto_star.

Tactic Notation "cases" "*" constr(E) "as" ident(H) :=
cases E as H; auto_star.
Tactic Notation "cases" "*" constr(E) :=
cases E; auto_star.
Tactic Notation "case_if" "*" :=
case_if; auto_star.
Tactic Notation "case_ifs" "*" :=
case_ifs; auto_star.
Tactic Notation "case_if" "*" "in" hyp(H) :=
case_if in H; auto_star.
Tactic Notation "cases_if" "*" :=
cases_if; auto_star.
Tactic Notation "cases_if" "*" "in" hyp(H) :=
cases_if in H; auto_star.
Tactic Notation "destruct_if" "*" :=
destruct_if; auto_star.
Tactic Notation "destruct_if" "*" "in" hyp(H) :=
destruct_if in H; auto_star.

Tactic Notation "cases'" "*" constr(E) "as" ident(H) :=
cases' E as H; auto_star.
Tactic Notation "cases'" "*" constr(E) :=
cases' E; auto_star.
Tactic Notation "cases_if'" "*" "as" ident(H) :=
cases_if' as H; auto_star.
Tactic Notation "cases_if'" "*" :=
cases_if'; auto_star.

Tactic Notation "decides_equality" "*" :=
decides_equality; auto_star.

Tactic Notation "iff" "*" :=
iff; auto_star.
Tactic Notation "iff" "*" simple_intropattern(I) :=
iff I; auto_star.
Tactic Notation "splits" "*" :=
splits; auto_star.
Tactic Notation "splits" "*" constr(N) :=
splits N; auto_star.

Tactic Notation "destructs" "*" constr(T) :=
destructs T; auto_star.
Tactic Notation "destructs" "*" constr(N) constr(T) :=
destructs N T; auto_star.

Tactic Notation "branch" "*" constr(N) :=
branch N; auto_star.
Tactic Notation "branch" "*" constr(K) "of" constr(N) :=
branch K of N; auto_star.

Tactic Notation "branches" "*" constr(T) :=
branches T; auto_star.
Tactic Notation "branches" "*" constr(N) constr(T) :=
branches N T; auto_star.

Tactic Notation "exists" "*" :=
exists; auto_star.
Tactic Notation "exists___" "*" :=
exists___; auto_star.
Tactic Notation "exists" "*" constr(T1) :=
exists T1; auto_star.
Tactic Notation "exists" "*" constr(T1) constr(T2) :=
exists T1 T2; auto_star.
Tactic Notation "exists" "*" constr(T1) constr(T2) constr(T3) :=
exists T1 T2 T3; auto_star.
Tactic Notation "exists" "*" constr(T1) constr(T2) constr(T3) constr(T4) :=
exists T1 T2 T3 T4; auto_star.
Tactic Notation "exists" "*" constr(T1) constr(T2) constr(T3) constr(T4)
constr(T5) :=
exists T1 T2 T3 T4 T5; auto_star.
Tactic Notation "exists" "*" constr(T1) constr(T2) constr(T3) constr(T4)
constr(T5) constr(T6) :=
exists T1 T2 T3 T4 T5 T6; auto_star.

Tactic Notation "exists" "*" constr(T1) "," constr(T2) :=
exists T1 T2; auto_star.
Tactic Notation "exists" "*" constr(T1) "," constr(T2) "," constr(T3) :=
exists T1 T2 T3; auto_star.
Tactic Notation "exists" "*" constr(T1) "," constr(T2) "," constr(T3) ","
constr(T4) :=
exists T1 T2 T3 T4; auto_star.
Tactic Notation "exists" "*" constr(T1) "," constr(T2) "," constr(T3) ","
constr(T4) "," constr(T5) :=
exists T1 T2 T3 T4 T5; auto_star.
Tactic Notation "exists" "*" constr(T1) "," constr(T2) "," constr(T3) ","
constr(T4) "," constr(T5) ","  constr(T6) :=
exists T1 T2 T3 T4 T5 T6; auto_star.

(* ################################################################# *)
(** * Tactics to Sort Out the Proof Context *)

(* ================================================================= *)
(** ** Hiding Hypotheses *)

(* Implementation *)

Definition ltac_something (P:Type) (e:P) := e.

Notation "'Something'" :=
(@ltac_something _ _).

Lemma ltac_something_eq : forall (e:Type),
e = (@ltac_something _ e).
Proof using. auto. Qed.

Lemma ltac_something_hide : forall (e:Type),
e -> (@ltac_something _ e).
Proof using. auto. Qed.

Lemma ltac_something_show : forall (e:Type),
(@ltac_something _ e) -> e.
Proof using. auto. Qed.

(** [hide_def x] and [show_def x] can be used to hide/show
  the body of the definition [x]. *)

Tactic Notation "hide_def" hyp(x) :=
let x' := constr:(x) in
let T := eval unfold x in x' in
change T with (@ltac_something _ T) in x.

Tactic Notation "show_def" hyp(x) :=
let x' := constr:(x) in
let U := eval unfold x in x' in
match U with @ltac_something _ ?T =>
  change U with T in x end.

(** [show_def] unfolds [Something] in the goal *)

Tactic Notation "show_def" :=
unfold ltac_something.
Tactic Notation "show_def" "in" hyp(H) :=
unfold ltac_something in H.
Tactic Notation "show_def" "in" "*" :=
unfold ltac_something in *.

(** [hide_defs] and [show_defs] applies to all definitions *)

Tactic Notation "hide_defs" :=
repeat match goal with H := ?T |- _ =>
  match T with
  | @ltac_something _ _ => fail 1
  | _ => change T with (@ltac_something _ T) in H
  end
end.

Tactic Notation "show_defs" :=
repeat match goal with H := (@ltac_something _ ?T) |- _ =>
  change (@ltac_something _ T) with T in H end.

(** [hide_hyp H] replaces the type of [H] with the notation [Something]
  and [show_hyp H] reveals the type of the hypothesis. Note that the
  hidden type of [H] remains convertible the real type of [H]. *)

Tactic Notation "show_hyp" hyp(H) :=
apply ltac_something_show in H.

Tactic Notation "hide_hyp" hyp(H) :=
apply ltac_something_hide in H.

(** [hide_hyps] and [show_hyps] can be used to hide/show all hypotheses
  of type [Prop]. *)

Tactic Notation "show_hyps" :=
repeat match goal with
  H: @ltac_something _ _ |- _ => show_hyp H end.

Tactic Notation "hide_hyps" :=
repeat match goal with H: ?T |- _ =>
  match type of T with
  | Prop =>
    match T with
    | @ltac_something _ _ => fail 2
    | _ => hide_hyp H
    end
  | _ => fail 1
  end
end.

(** [hide H] and [show H] automatically select between
  [hide_hyp] or [hide_def], and [show_hyp] or [show_def].
  Similarly [hide_all] and [show_all] apply to all. *)

Tactic Notation "hide" hyp(H) :=
first [hide_def H | hide_hyp H].

Tactic Notation "show" hyp(H) :=
first [show_def H | show_hyp H].

Tactic Notation "hide_all" :=
hide_hyps; hide_defs.

Tactic Notation "show_all" :=
unfold ltac_something in *.

(** [hide_term E] can be used to hide a term from the goal.
  [show_term] or [show_term E] can be used to reveal it.
  [hide_term E in H] can be used to specify an hypothesis. *)

Tactic Notation "hide_term" constr(E) :=
change E with (@ltac_something _ E).
Tactic Notation "show_term" constr(E) :=
change (@ltac_something _ E) with E.
Tactic Notation "show_term" :=
unfold ltac_something.

Tactic Notation "hide_term" constr(E) "in" hyp(H) :=
change E with (@ltac_something _ E) in H.
Tactic Notation "show_term" constr(E) "in" hyp(H) :=
change (@ltac_something _ E) with E in H.
Tactic Notation "show_term" "in" hyp(H) :=
unfold ltac_something in H.

(** [show_unfold R] unfolds the definition of [R] and
  reveals the hidden definition of R. --todo:test,
  and implement using unfold simply *)
  (* --todo: change "unfolds" *)

Tactic Notation "show_unfold" constr(R1) :=
unfold R1; show_def.
Tactic Notation "show_unfold" constr(R1) "," constr(R2) :=
unfold R1, R2; show_def.

(* ================================================================= *)
(** ** Sorting Hypotheses *)

(** [sort] sorts out hypotheses from the context by moving all the
  propositions (hypotheses of type Prop) to the bottom of the context. *)

Ltac sort_tactic :=
try match goal with H: ?T |- _ =>
match type of T with Prop =>
  generalizes H; (try sort_tactic); intro
end end.

Tactic Notation "sort" :=
sort_tactic.

(* ================================================================= *)
(** ** Clearing Hypotheses *)

(** [clears X1 ... XN] is a variation on [clear] which clears
  the variables [X1]..[XN] as well as all the hypotheses which
  depend on them. Contrary to [clear], it never fails. *)

Tactic Notation "clears" ident(X1) :=
let rec doit _ :=
match goal with
| H:context[X1] |- _ => clear H; try (doit tt)
| _ => clear X1
end in doit tt.
Tactic Notation "clears" ident(X1) ident(X2) :=
clears X1; clears X2.
Tactic Notation "clears" ident(X1) ident(X2) ident(X3) :=
clears X1; clears X2; clears X3.
Tactic Notation "clears" ident(X1) ident(X2) ident(X3) ident(X4) :=
clears X1; clears X2; clears X3; clears X4.
Tactic Notation "clears" ident(X1) ident(X2) ident(X3) ident(X4)
ident(X5) :=
clears X1; clears X2; clears X3; clears X4; clears X5.
Tactic Notation "clears" ident(X1) ident(X2) ident(X3) ident(X4)
ident(X5) ident(X6) :=
clears X1; clears X2; clears X3; clears X4; clears X5; clears X6.

(** [clears] (without any argument) clears all the unused variables
  from the context. In other words, it removes any variable
  which is not a proposition (i.e. not of type Prop) and which
  does not appear in another hypothesis nor in the goal. *)
(* --todo: rename to clears_var ? *)

Ltac clears_tactic :=
match goal with H: ?T |- _ =>
match type of T with
| Prop => generalizes H; (try clears_tactic); intro
| ?TT => clear H; (try clears_tactic)
| ?TT => generalizes H; (try clears_tactic); intro
end end.

Tactic Notation "clears" :=
clears_tactic.

(** [clears_all] clears all the hypotheses from the context
  that can be cleared. It leaves only the hypotheses that
  are mentioned in the goal. *)

Ltac clears_or_generalizes_all_core :=
repeat match goal with H: _ |- _ =>
         first [ clear H | generalizes H] end.

Tactic Notation "clears_all" :=
generalize ltac_mark;
clears_or_generalizes_all_core;
intro_until_mark.

(** [clears_but H1 H2 .. HN] clears all hypotheses except the
  one that are mentioned and those that cannot be cleared. *)

Ltac clears_but_core cont :=
generalize ltac_mark;
cont tt;
clears_or_generalizes_all_core;
intro_until_mark.

Tactic Notation "clears_but" :=
clears_but_core ltac:(fun _ => idtac).
Tactic Notation "clears_but" ident(H1) :=
clears_but_core ltac:(fun _ => gen H1).
Tactic Notation "clears_but" ident(H1) ident(H2) :=
clears_but_core ltac:(fun _ => gen H1 H2).
Tactic Notation "clears_but" ident(H1) ident(H2) ident(H3) :=
clears_but_core ltac:(fun _ => gen H1 H2 H3).
Tactic Notation "clears_but" ident(H1) ident(H2) ident(H3) ident(H4) :=
clears_but_core ltac:(fun _ => gen H1 H2 H3 H4).
Tactic Notation "clears_but" ident(H1) ident(H2) ident(H3) ident(H4) ident(H5) :=
clears_but_core ltac:(fun _ => gen H1 H2 H3 H4 H5).

Lemma demo_clears_all_and_clears_but :
forall x y:nat, y < 2 -> x = x -> x >= 2 -> x < 3 -> True.
Proof using.
introv M1 M2 M3. dup 6.
(* [clears_all] clears all hypotheses. *)
clears_all. auto.
(* [clears_but H] clears all but [H] *)
clears_but M3. auto.
clears_but y. auto.
clears_but x. auto.
clears_but M2 M3. auto.
clears_but x y. auto.
Qed.

(** [clears_last] clears the last hypothesis in the context.
  [clears_last N] clears the last [N] hypotheses in the context. *)

Tactic Notation "clears_last" :=
match goal with H: ?T |- _ => clear H end.

Ltac clears_last_base N :=
match number_to_nat N with
| 0 => idtac
| S ?p => clears_last; clears_last_base p
end.

Tactic Notation "clears_last" constr(N) :=
clears_last_base N.


(* ################################################################# *)
(** * Compatibility with standard library *)

(** The module [Program] contains definitions that conflict with the
  current module. If you import [Program], either directly or indirectly
  (e.g. through [Setoid] or [ZArith]), you will need to import the
  compability definitions through the top-level command:
  [Import LibTacticsCompatibility]. *)

Module LibTacticsCompatibility.
Tactic Notation "apply" "*" constr(H) :=
  sapply H; auto_star.
Tactic Notation "subst" "*" :=
  subst; auto_star.
End LibTacticsCompatibility.

Open Scope nat_scope.