Compile error ghc 7.8.2

[jgm]

Building HCodecs-0.3...
Preprocessing library HCodecs-0.3...
[1 of 7] Compiling Data.Arbitrary   ( src/Data/Arbitrary.hs, dist/build/Data/Arbitrary.o )
[2 of 7] Compiling Data.ByteString.Builder ( src/Data/ByteString/Builder.hs, dist/build/Data/ByteString/Builder.o )

src/Data/ByteString/Builder.hs:65:1: Warning:
    Module ‘Foreign’ does not export ‘unsafePerformIO’
[3 of 7] Compiling Data.ByteString.Parser ( src/Data/ByteString/Parser.hs, dist/build/Data/ByteString/Parser.o )

src/Data/ByteString/Parser.hs:115:1: Warning:
    Module ‘Foreign’ does not export ‘unsafePerformIO’

src/Data/ByteString/Parser.hs:122:1: Warning:
    Module ‘Control.Monad.ST’ does not export ‘unsafeInterleaveST’

src/Data/ByteString/Parser.hs:332:1: Warning:
    Local definition of ‘join’ clashes with a future Prelude name - this will become an error in GHC 7.10, under the Applicative-Monad Proposal.
[4 of 7] Compiling Data.Audio       ( src/Data/Audio.hs, dist/build/Data/Audio.o )

src/Data/Audio.hs:103:21:
    Not in scope: ‘unsafeFreeze’
    Perhaps you meant ‘unsafeFreezeAux’ (line 103)

src/Data/Audio.hs:106:54: Not in scope: ‘unsafeThaw’
Failed to install HCodecs-0.3
cabal: Error: some packages failed to install:
HCodecs-0.3 failed during the building phase. The exception was:
ExitFailure 1

I tried relaxing the version constraint in music-score to allow HCodecs 0.5, but then got this:

[18 of 71] Compiling Data.Semigroup.Instances ( src/Data/Semigroup/Instances.hs, dist/build/Data/Semigroup/Instances.o )

src/Data/Semigroup/Instances.hs:18:1:
    Duplicate instance declarations:
      instance Num a => Num (Sum a)
        -- Defined at src/Data/Semigroup/Instances.hs:18:1
      instance Num a => Num (Sum a) -- Defined in ‘Data.Monoid’

src/Data/Semigroup/Instances.hs:33:1:
    Duplicate instance declarations:
      instance Num a => Num (Product a)
        -- Defined at src/Data/Semigroup/Instances.hs:33:1
      instance Num a => Num (Product a) -- Defined in ‘Data.Monoid’
Failed to install music-score-1.7
cabal: Error: some packages failed to install:
music-score-1.7 failed during the building phase. The exception was:
ExitFailure 1

Even if you're mainly supporting the latest HP (ghc 7.6.x), a new HP will be out soon with ghc 7.8.x, and it would be good to fix things.

[hanshoglund]

Agreed, thanks!