Usage: ghci [command-line-options-and-input-files] The kinds of input files that can be given on the command-line include: - Haskell source files (.hs or .lhs suffix) - Object files (.o suffix, or .obj on Windows) - Dynamic libraries (.so suffix, or .dll on Windows) In addition, ghci accepts most of the command-line options that plain GHC does. Some of the options that are commonly used are: -fglasgow-exts Allow Glasgow extensions (unboxed types, etc.) -i Search for imported modules in the directory . -H32m Increase GHC's default heap size to 32m -cpp Enable CPP processing of source files Full details can be found in the User's Guide, an online copy of which can be found here: http://www.haskell.org/ghc/documentation.html