[Haskell-cafe] Re: nondet function

[Aaron Denney]

On 2006-09-10, Ashley Yakeley <ashley at semantic.org> wrote:
> Is it possible to write nondet?
>
>   nondet :: a -> a -> a
>
>   nondet _|_ _|_ = _|_
>   nondet _|_ q = q
>   nondet p _|_ = p
>   nondet p q = p or q
>
> nondet evaluates its arguments in parallel, and returns the first one of 
> them to evaluate. It's thus a bit different from the "par" of GPH. This 
> isn't referentially transparent, of course, but maybe it could be 
> written in the IO monad:
>
>   nondet p q = unsafePerformIO (getnondet p q)
>
>   getnondet :: a -> a -> IO a

Can you pass p and q to two new threads, have them each force their
argument, and then write it to the same channel?   Then read from that
channel once in the original thread.

-- 
Aaron Denney
-><-