free haskell compilers
nhc is small, portable, standards-compliant compiler for Haskell 98. It comes with extensive tool support for automatic compilation, foreign language interfacing, heap and time profiling, tracing, and debugging.

nhc98 is available for all 32-bit Unix-like platforms (including MacOS-X, Cygwin/Windows, Linux, Solaris, *BSD, AIX, HP-UX, Ultrix, IRIX)
Yhc is a Haskell 98 Compiler. Based on nhc98, but with an entirely rewritten backend, it takes lots of good features from nhc98, and adds lots of new ones.