Could not find module ‘Control.Parallel.Strategies’

[calvinb]

@jorendorff when I

make play

on your Haskell project, I get

Minimax.hs:9:8:
    Could not find module ‘Control.Parallel.Strategies’

Is there something out of place in the source, or do you think this is a problem with my environment? I'm on Yosemite using ghc from brew. Thanks.

[jorendorff]

Oh. It's an external package that you have to install. I commented it in Minimax.hs, but I should have instead documented it in the README or something...

[jorendorff]

The comment I meant is this one, it'll tell you what to do:

-- Hi! If this import doesn't work for you, you just need to `cabal install parallel`. :)
import Control.Parallel.Strategies(parMap, parTuple2, r0, rseq)
-- Or you can just delete it, and change the following line of code to:
--     pmap = map
--
-- pmap computes exactly the same thing as map, when it works. There are just two differences:
-- 1.  pmap can only produce lists of pairs.
-- 2.  pmap spreads out the computation across multiple CPU cores when you run with +RTS -N4.
pmap = parMap (parTuple2 r0 rseq)

[calvinb]

@jorendorff That got me past that error and on to another one:

Minimax.hs:113:1:
    Non type-variable argument in the constraint: Eq (Move g)
    (Use FlexibleContexts to permit this)
    When checking that ‘bestMoveWithDepthLimit’ has the inferred type
      bestMoveWithDepthLimit :: forall g.
                                (Eq (Move g), Show (Move g), Game g) =>
                                (g -> Float) -> Int -> g -> Move g

Do you have FlexibleContexts enabled? If so, haven't found how to do that except through the source, so I'm curious. Thanks for your help.

[jorendorff]

@calvinb That can be fixed by upgrading to a newer GHC (or by adding FlexibleContexts to the source, and I would totally take a PR for that).