I don't see why the architecture of macports stuff would make a difference. I should perhaps have said in the original post that I have no macports haskell software installed. I am not using the macports haskell-platform port. I am using the OS X Haskell Platform package downloaded from the web: Haskell Platform 2011.2.0.1-i386.pkg. To answer your question, though, here is the gtk2 macports info: