The actions performed by unsafePerformIO are simply done at some entirely unpredictable time, perhaps interleaved with actions on the main execution path.
The formal semantics in the notes doesn't have a good way to express that because the purely-functional part is given a denotational semantics... yet unsafePerformIO can occur in the middle of that. So it's tiresome to characterise in theory, and hard to predict in practice. You should only use it when the state it is fiddling with is well partitioned. Simon | -----Original Message----- | From: David Sabel [mailto:[EMAIL PROTECTED]] | Sent: 20 September 2002 13:48 | To: Simon Peyton-Jones; [EMAIL PROTECTED] | Subject: unsafePerformIO | | In read your paper ""Tackling the Awkward Squad: monadic input / output, | concurrency, exceptions, and foreign-language calls in Haskell", and have | a question about unsafePerformIO. | | In your operational semantic of the IO-Monad you tell nothing about, how | 'unsafe' IO actions are performed, is there another paper / documentation | about | this available, or can you - or someone else - give me a review about that? | | David | JWGU Frankfurt | _______________________________________________ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
