Giters

conal / MemoTrie

Trie-based memo functions

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool

Unsupported extension: EmptyCase

cryptid11 opened this issue · comments

commented

cabal install Memotrie

Resolving dependencies...
Configuring MemoTrie-0.6.4...
Building MemoTrie-0.6.4...
Preprocessing library MemoTrie-0.6.4...

src/Data/MemoTrie.hs:3:51: Unsupported extension: EmptyCase
Failed to install MemoTrie-0.6.4
cabal: Error: some packages failed to install:
MemoTrie-0.6.4 failed during the building phase. The exception was:
ExitFailure 1

Seems it doesn't works with the standard haskell-platform on ubuntu, that install "The Glorious Glasgow Haskell Compilation System, version 7.6.3" now I'm going to install the last one 7.8.2 and hope it works...

Seems it create a mess since after few command I arrive here: https://www.fpcomplete.com/user/simonmichael/how-to-cabal-install#could-not-resolve-dependencies--cabal-hell

So sad they are not able to let you use a building envinroment, anyway I'd like the error output to be more specific, also, can you explain me why it doesn't works?

commented

Oh, hm. Perhaps the EmptyCase language extension got added after 7.6.3. Sorry about that. It's easy to replace the \case line. For instance,

  untrie VoidTrie = \ _ -> error "untrie VoidTrie"
                    -- \case  -- needs EmptyCase
commented

@hvr Thanks for the pointers and patching the dependencies. The .cabal now contains

  if impl(ghc >= 7.10.0)
     Build-Depends: base >=4.8.0.0 && <5 
  else
     Build-Depends: base <4.8.0.0, void

For my next release, I gather that I'll want to change the .cabal file. Right? If so, could you suggest a replacement for these lines?

commented

@conal that depends on what you intend to support. Do you want to support only GHC >= 7.8 in future releases? Or do you want to add some compatibility workaround for GHC 7.6 and older?