Text Edit won't save with correct file extension
I am trying to edit Haskell files with Text Edit. However when I save the file it automatically adds .txt or .rtf and won't let me use .txt. Even when I go into finder and change the file extension it immediately changes it back to .rtf or .txt. It works when I save perl files. How do I get Text Edit to save Haskell files? I am using Lion.
MacBook Pro (15-inch Mid 2010)