10.04.2012, 02:00, "Ryan Ingram" <ryani.s...@gmail.com>: > A concurring opinion here, and an example. > > iff :: Bol -> a -> a -> a > iff True x _ = x > iff False _ x = x > > f, g :: Bool -> Bool > f x = x > g x = iff x True False > > Are these two functions equal? I would say yes, they are. Yet once you can > pattern match on functions, you can easily tell these functions apart, and > create a function > > h :: (Bool -> Bool) -> Bool > such that h f => True but h g => False. > > -- ryan
I've just remembered an interesting statement that there is a language where each equivalence class of programs Dan Doel mentioned (f = g iff forall x. f x = g x) has a single program in it. That is there is a one-to-one correspondence between programs and functions. Though as far as I understood one cannot construct a translator from this language to another language. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
