I seem to remember that on Windows there are subtleties to do with whether the pipe ends are inheritable by subprocesses or not. See mkAnonPipe() in the process package for how we deal with this already in
#8943: Add System.Process.createPipe --------------------------------------+------------------------------------ Reporter: tibbe | Owner: Type: feature request | Status: patch Priority: normal | Milestone: 7.10.1 Component: libraries/process | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Comment (by tibbe): simonmar added this info to the discussion thread: process. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8943#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler