John Meacham
In a concurrent implementation, a thread performing an infinite loop with no IO or interaction with the outside world can potentially stall switching to another thread forever, in FP, we usually denote an infinite loop by _|_. so I think the first difference would be:
By infinite loop, you mean both non-terminating, and non-productive. A non-terminating but productive pure computation (e.g. ones = 1:ones) is not necessarily a problem. Why? Because ultimately the demand that forces production of the infinite data structure must come from somewhere, and that somewhere must essentially be I/O. (The only alternative consumers are terminating pure (no problem), non-terminating productive pure (so look upward to its demand), or an unproductive non-terminating computation, which brings us full circle.) It is a curious artifact that in certain multi-threaded implementations, a non-terminating non-productive thread does not make the entire system unproductive, but I don't think this is a behaviour anyone would want to rely on. I would say such a program has a bug, and the threaded RTS is just masking it. Regards, Malcolm