how to fix haskell goodness on the mac

gistfile1.txt

1) figure out where the cabal-install installed binarys lie,
they're probably installed at .cabal/bin
don't touch that subfolder (but when you uninstall  ghc  / the haskell platform, remove everything else, except maybe the .caba/config file, which you may want to adjust to set the 
compile profiling libs to true, though that has a 2x increase in compile time )

2) make sure you have ghc 7.0.3 because if you've upgraded to xcode 4 
you need it (and even if you do the alternate fix, 7.0.3 has some bug fixes)

2.5) if you don't have ghc 7.0.3, go to the ghc website. Also be sure to DL the 64 bit version
because  I don't believe that you get any upside when linking to libs if they're 64bit from a 32 compiled piece of code (ie you cant!)

3) remove the previous ghc / haskell platform install (but keep the .cabal/bin) dir that you've hopefully added to your path :)

4) make sure that for whatever ffi / c code dependencies, you have the associated c libs. I like to use mac homebrew to install those to /usr/local/whatever

5) install ghc the new version, do cabal update,  cabal install happiness