arrowp (hackage): A preprocessor that reads Haskell with arrow notation and outputs Haskell 98.  Note that GHC 6.2 or later has built-in support for arrow notation, so if you're only using GHC, you don't need this preprocessor: just rename your arrow module as an ordinary Haskell source file and add a LANGUAGE Arrows pragma at the top.  GHC also gives better error messages for arrow code.
Keywords: development|program