Graham Klyne wrote: > At 12:27 11/11/04 +0000, Ben Rudiak-Gould wrote: [..] > >going to be safe, because it's just not the case that > > > > x = once (newIORef ()) > > y = x > > > >has the same intended meaning as > > > > x = once (newIORef ()) > > y = once (newIORef ()) > > > >No amount of compiler-specific magic is going to fix this. > > Ah, yes, I take the point now. > > Isn't this generally the case for any value in the IO monad? (Brushing a > murky area of equivalence; the same IO computation used twice may yield > different results, so I'm not clear to what extent it is meaningful to say > that any IO value is the same as any other, including itself, in any > observable sense.)
No. "getChar" is always "the IO operation that reads a character from stdin". You can always substitute one instance of "getChar" for another; you can even say "foo = getChar" and substitute "foo" for every occurrence of "getChar". A value of type IO a is a *computation*; its result may change, but the computation itself cannot. --KW 8-) _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
