Well, the case of the built-in numeric types is somewhat different, but most functions automatically short circuit, since Haskell uses lazy evaluation.
For instance, it's perfectly okay to define myAnd = foldr (&&) True Note that this terminates on infinite lists which contain False as a value: myAnd (False : repeat True) will evaluate to False pretty much immediately. - Cale On 25/06/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > Some simplifications might help you here... > > > prodList [] = 1 > > prodList (0:xs) = 0 > > prodList (x:xs) = x * prodList xs > > Simplified: > prodList xs = foldl (*) 1 xs > > But my original at least made some provision for short circuiting the > whole operation if the list contained a 0. As far as I can figure, > fold, map, etc., are not suitable for any situation in which > short-circuiting would be desirable (e.g. and, or, etc.). Am I wrong? > > (I realize that, given that the function product is already available, > there is no point in defining my function prodList above, but my > question is a more general one, having to do with how best to > implement short-circuiting.) > > Thanks! > > kj > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
