[Haskell-beginners] Error when running `cabal install cabal-install`

[Ryan Schmidt]

> On Apr 23, 2015, at 7:23 PM, Peng Yu <pengyu.ut at gmail.com> wrote:
> 
>> Long story short: Try
>> $> cabal install --extra-include-dirs=/opt/local/include --extra-lib-dirs=/opt/local/lib
> 
> I tried it but it still shows the error messages.
> 
> ~$ cabal install --extra-include-dirs=/opt/local/include
> --extra-lib-dirs=/opt/local/lib cabal-install
> 
> Resolving dependencies...
> Configuring cabal-install-1.22.3.0...
> Failed to install cabal-install-1.22.3.0
> Build log ( /Users/py/.cabal/logs/cabal-install-1.22.3.0.log ):
> cabal: Error: some packages failed to install:
> cabal-install-1.22.3.0 failed during the configure step. The exception was:
> user error ('/usr/bin/ghc' exited with an error:

You've installed ghc into /usr/bin? That's probably not a good idea. Prefix /usr is only for the OS vendor to install software into.