non blocking System.system?

John Meacham john at
Wed Oct 8 15:02:46 EDT 2003

I was curious if there was a version of System.system floating about
which doesn't block all threads when doing concurrency? just doing an
actual fork and exec isn't sufficient because I need to do haskell
things (like write to MVars) after the spawned app finishes.

I imagine this might be written by catching sigCHLD and writing to an
mvar, but I can't seem to get at the siginfo_t structure from the
haskell signal callback to find out the pid of the process which died.

John Meacham - California Institute of Technology, Alum. - john at

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