gistfile1.txt

==> Downloading http://www.haskell.org/ghc/dist/7.8.1-rc2/ghc-7.8.0.20140228-src.tar.bz2
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==> Downloading https://www.haskell.org/ghc/dist/7.8.1-rc2/ghc-7.8.0.20140228-x86_64-apple-darwin-lion.tar.bz2
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==> ./configure --prefix=/private/tmp/ghc-khpP/ghc-7.8.0.20140228/subfo --with-gcc=clang
==> make -j1 install
==> ./configure --prefix=/usr/local/Cellar/ghc/7.8.0.20140228 --build=x86_64-apple-darwin --with-gcc=clang
==> make
libraries/Cabal/Cabal/Distribution/Version.hs:700:19:
    Parse error in pattern: Parse.skipSpaces
    Possibly caused by a missing 'do'?
make[1]: *** [utils/ghc-cabal/dist/build/tmp/ghc-cabal] Error 1
make: *** [all] Error 2

READ THIS: https://github.com/Homebrew/homebrew/wiki/troubleshooting

These open issues may also help:
ghc 7.8.2 dynamic linking problem (https://github.com/Homebrew/homebrew/issues/29241)
ghc --devel failed to build on 10.9.2 (https://github.com/Homebrew/homebrew/issues/30000)