Now that's rapid maintenance, but it's still version hell because you've got to have that compiler installed first (even though HP is supposed to be a way to acquire haskell) and you probably haven't. You've probably got the one from the linux package which hasn't been maintained since, ooh, must have been at least a week ago, so you install the new one and you've trashed cabal. How long is that puzzle gonna take to unravel?
About 12 seconds, if you read http://www.haskell.org/platform/linux.html:
Download the source tarball for Unix-like systems: here
- *haskell-platform-2012.4.0.0.tar.gzhttp://lambda.haskell.org/platform/download/2012.4.0.0/haskell-platform-2012... * - SHA-1: 7976508c50305969f64c721a1d095ae22efff8b7
Get and install GHC 7.4.2 prior to building the platform:
- GHC 7.4.2 http://haskell.org/ghc/download_ghc_7_4_2.html
Finally, unpack the Haskell Platform source tarball, and run (possibly with 'sudo'):
./configure
make
make install
Also, the Haskell Platform ./configure step checks which version of GHC you have installed, and requires you to pass the option --enable-*unsupported*-* ghc*-version in order to compile it with anything other than GHC 7.4.2. Did you try an unsupported version? And now you're complaining?