----- Original Message -----
From: "Simon Marlow"
As for sharing, we currently don't provide any guarnatees, although we should. It is currently the case that if you write
a = unsafePerformIO (putStr "hello") b = unsafePerformIO (putStr "hello")
and both a and b are evaluated, then you may get either one or two "hello"s on stdout. You can currently make things more deterministic by (a) adding NOINLINE pragmas for a and b, and (b) using the flag -fno-cse to disable common sub-expression elimination. Then you'll get exactly two instances of "hello" on stdout, although we won't guarantee that behaviour for ever. At some point we'll fix it so that unsafePerformIO applications are never duplicated or coalesced.
Are there any (short) examples available where using of unsafePerformIO leads to unexpected behaviour, especially an example with the terms a and b from above? with best regards, David ------------- JWGU Frankfurt