I propose adding some functionality to the readline package (really just wrappers of variables from that library) which is necessary to fix ghci bug #998. See the proposed patch at http://hackage.haskell.org/trac/ghc/ticket/1141 as well as the bug report at http://hackage.haskell.org/trac/ghc/ticket/998 The main addition is rl_completion_word_break_hook, which lets us change the set of word break characters based on the context of the line. Specifically for ghci, this is needed to change whether "/" is a word boundary (depending on whether we're expanding a Haskell name or a filename). Note that this variable is only present in readline version 5.0 or later; I've put in some ifdef's to support compiling against older versions. I've also included get/set functions for the rl_attempted_completion_over variable. If it's set to nonzero, readline won't use its default completer when our custom completer returns no results. Thanks, -Judah