Hi Miguel, That's a nice way of writing it.
Thanks, -John On Fri, Feb 13, 2009 at 10:42 AM, Miguel Mitrofanov <miguelim...@yandex.ru>wrote: > What do you need that for? > > Can you live with > > infixl |$| > (|$|) :: [a -> r] -> a -> [r] > fs |$| x = map ($ x) fs > > and, instead of "broadcast fs a b" use > > fs |$| a |$| b > > ? > > > On 13 Feb 2009, at 02:34, John Ky wrote: > > Hi Haskell Cafe, >> >> I tried using type families over functions, but when I try it complains >> that the two lines marked conflict with each other. >> >> class Broadcast a where >> type Return a >> broadcast :: a -> Return a >> >> instance Broadcast [a -> r] where >> type Return [a -> r] = a -> [r] -- Conflict! >> broadcast fs a = [] >> >> instance Broadcast [a -> b -> r] where >> type Return [a -> b -> r] = a -> b -> [r] -- Conflict! >> broadcast fs a b = [] >> >> Given that in Haskell, every function of n+1 arguments is also a function >> of n arguments, this is likely the cause of the conflict. >> >> In this case, currying is not my friend. >> >> Unfortunately this means I'm stuck with numbered function names: >> >> bc0 :: [r] -> [r] >> bc0 rs = rs >> >> bc1 :: [a -> r] -> a -> [r] >> bc1 [] a = [] >> bc1 (r:rs) a = (r a):bc1 rs a >> >> bc2 rs a b = rs `bc1` a `bc1` b >> >> bc3 rs a b c = rs `bc1` a `bc1` b `bc1` c >> >> -- etc >> >> Cheers, >> >> -John >> >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe@haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> > >
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