> So you say (and I do agree). But how can I *observe* that they are the same?
Well, not with a single program run (obviously). But it is the case that for any program P and input sequence X (i.e., keys pressed): running P with X and running {foo = getChar; P'} with X (where P' is P with all occurrences of getChar replaced by foo) will behave identically. --KW 8-) _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe