hegg v0.5

• Change 'modifyA' to instead operate over e-graphs, instead of being
  constrained to editing the e-class that prompted the modification.
  (Remember that the e-graph lenses in 'Data.Equality.Graph.Lens' are the
  preferred way to edit the e-graph and the desired e-class (by id), and its
  data, etc...)

• Fix compilation of Data.Equality.Graph.Dot, the graphviz rendering backend
  (despite there being some usability bugs still) (by @BinderDavid)

• Dropped support for GHC 9.0 because of the QuantifiedConstraints bug (by @phadej)

• Add AnalysisM, a class for e-graph analysis that are only well-defined
  within a certain monadic context. Accordingly, we also add versions of the
  current e-graph transformation functions (such as add and merge) for
  analysis defined monadically (such as addM and mergeM).

• Add operation to create empty e-classes with explicit domain data
  (experimental, not sure whether this is something good to keep in the API)

hegg v0.4

• Make Language a constraint type synonym instead of a standalone empty class
• Use QuantifiedConstraints instead of Eq1,Ord1,Show1 in the implementation,
  which results in the user only having to provide an Eq a => Eq (language a) instance rather than a Eq1 language one (which is much simpler and can
  usually be done automatically!)
• Make _classes a Traversal lens over all e-classes rather than a Lens into IntMap EClass

hegg v0.3

• A better Analysis tutorial in the README.

• Complete Analysis redesign.

  • The Analysis class now has two type parameters: a domain and a
    language, and no longer has an associated type family
  • The analysis no longer has any knowledge of the e-graph:
    • makeA now has type l domain -> domain, that is, to make a domain
      of a new node we only have to take into consideration the data of
      the sub-nodes of the new node.
    • joinA is unchanged.
    • modifyA now has type EClass domain lang -> (EClass domain lang, [Fix lang]). It takes an e-class and optionally modifies it,
      possibly by adding nodes to it. The return value is the modified
      e-class, and a list of expressions from the language to add to the
      e-class.
  • We can now compose analysis and create language-polymorphic analysis. Such
    two examples are the analysis with domain () which regardless of the
    language simply ignores the domain: instance Analysis () l; and the
    second example is the product of analysis, which composes two separate
    analysis into one: instance (Analysis a l, Analysis b l) => Analysis (a,b) l.
  • An EGraph now also has two type parameters instead of one (the latter is
    the language is the former the domain of the analysis).

• Allow customization of Schedulers through parameters (by accepting a scheduler
  rather than a proxy for it)

hegg v0.2

What's Changed

• Expose runEqualitySaturation to run equality saturation on existing e-graphs
  whole instead of focusing on individual expressions
• (Very) significant performance improvements!
• Make CostFunction polymorphic over the Cost type, requiring that type
  to instance Ord
• Make e-graph abstract. The internal structure can still be modified through
  the available lenses in Data.Equality.Graph.Lens
• Fix a bug related to NodeMap's size.

Full Changelog: v0.1.0.0...v0.2.0.0

hegg v0.1

First release of hegg: e-graphs and equality saturation in Haskell

Release discussion:

• Haskell Discourse
• r/haskell