Error building dependencies in GHC 8

[mcandre]

Hi, I'm trying to access the choice function from the random-extras package in GHC 8, however one of random-extras' dependencies, rvar-0.2.0.3, fails to install. Could random-extras reimplement fix the build tree for GHC 8?

$ cabal install random-extras
...
Resolving dependencies...
Downloading log-domain-0.12...
Configuring flexible-defaults-0.0.1.2...
Configuring log-domain-0.12...
Building flexible-defaults-0.0.1.2...
Failed to install flexible-defaults-0.0.1.2
Build log ( /Users/andrew/.cabal/logs/ghc-8.4.1/flexible-defaults-0.0.1.2-5YVuvRryN6dKBYkpG8slnb.log ):
cabal: Entering directory '/var/folders/53/300vy1ys7tv8h8fr_z3tm8gr0000gn/T/cabal-tmp-68096/flexible-defaults-0.0.1.2'
Configuring flexible-defaults-0.0.1.2...
Preprocessing library for flexible-defaults-0.0.1.2..
Building library for flexible-defaults-0.0.1.2..
[1 of 3] Compiling Language.Haskell.TH.FlexibleDefaults.Solve ( src/Language/Haskell/TH/FlexibleDefaults/Solve.hs, dist/build/Language/Haskell/TH/FlexibleDefaults/Solve.o )

src/Language/Haskell/TH/FlexibleDefaults/Solve.hs:13:1: warning: [-Wunused-imports]
    The import of ‘Data.Monoid’ is redundant
      except perhaps to import instances from ‘Data.Monoid’
    To import instances alone, use: import Data.Monoid()
   |
13 | import Data.Monoid 
   | ^^^^^^^^^^^^^^^^^^
[2 of 3] Compiling Language.Haskell.TH.FlexibleDefaults.DSL ( src/Language/Haskell/TH/FlexibleDefaults/DSL.hs, dist/build/Language/Haskell/TH/FlexibleDefaults/DSL.o )

src/Language/Haskell/TH/FlexibleDefaults/DSL.hs:24:10: error:
    • No instance for (Semigroup (Impls s))
        arising from the superclasses of an instance declaration
    • In the instance declaration for ‘Monoid (Impls s)’
   |
24 | instance Monoid (Impls s) where
   |          ^^^^^^^^^^^^^^^^
cabal: Leaving directory '/var/folders/53/300vy1ys7tv8h8fr_z3tm8gr0000gn/T/cabal-tmp-68096/flexible-defaults-0.0.1.2'
Building log-domain-0.12...
Installed log-domain-0.12
cabal: Error: some packages failed to install:
flexible-defaults-0.0.1.2-5YVuvRryN6dKBYkpG8slnb failed during the building
phase. The exception was:
ExitFailure 1
hscharm-0.0.1-2sR9rPsnwG4qKDuRsupr0 depends on hscharm-0.0.1 which failed to
install.
random-extras-0.19-HQHjDk80wOkFDKkp8CNQyT depends on random-extras-0.19 which
failed to install.
random-fu-0.2.7.0-KW7mlIb5wDTKCMDAGjJKbE depends on random-fu-0.2.7.0 which
failed to install.
random-source-0.3.0.6-KbJteEsOOeBIWQGMWuMNT3 depends on random-source-0.3.0.6
which failed to install.
rvar-0.2.0.3-375a3ypLolVJNDmT1DhOf1 depends on rvar-0.2.0.3 which failed to
install.

I'm using ghc 8.4.1, cabal 2.2.0.0, on macOS 10.13 High Sierra.

As a workaround, I'm using head . System.Random.Shuffle.shuffle' with the random-shuffle package.

[retnuh]

This also fails (on the same dependency, flexible-defaults-0.0.1.2) when trying to install lambdabot.