RE: Concurrent question

Suppose I have a program with two (ghc-)threads, one that does execute some `system' commands, and another one that accepts socket connections.

While the system thread waits (for the system call to finish), will the other thread be awake (and accept new connections)?

No, unfortunately not. GHC's runtime system doesn't currently support threads waiting on process completion, so these operations will block the whole system at the moment. Cheers, Simon