On 12/08/2010 21:59, Yitzchak Gale wrote:
Wei Hu wrote:
nonTermination _ = blackhole where blackhole = blackhole
My original example was actually:
process :: String -> String process = let x = x in x
Ah yes, that works too. But other similar versions don't, like this one: process :: String -> String process _ = let x = x in x Hence why I added the "tail" in my version. So what happens is this: - the recursive definition causes the main thread to block on itself (known as a "black hole") - the program is deadlocked (no threads to run), so the runtime invokes the GC to see if any threads are unreachable - the GC finds that (a) the main thread is unreachable and blocked on a blackhole, so it gets a NonTermination exception (b) the Handle is unreachable, so its finalizer is started - the finalizer runs first, and closes the Handle - the main thread runs next, and the exception handler for writeFile tries to close the Handle, which has already been finalized Really hClose shouldn't complain about a finalized handle, I'll see if I can fix that. Cheers, Simon