2009/7/21 Roel van Dijk
I am also wondering what the following would/should mean:
(1, , ( , 2), ) 'a' 'b' 'c'
I would expect it to be a type error, since I think the following is the only sane type the tuple can have (assuming numeric literals :: Int):
(1, , ( , 2), ) :: a -> b -> (Int, a, c -> (c, Int), b)
Ganesh
Ah you're completely right! I would be applying a tuple to a Char which is nonsense.
You can kind of do it if you indicate which 'field' is to be applied: import Control.Applicative newtype Fst b a = Fst (a,b) deriving (Show) newtype Snd a b = Snd (a,b) deriving (Show) instance Functor (Fst b) where fmap f (Fst (a,b)) = Fst (f a,b) instance Functor (Snd a) where fmap f (Snd (a,b)) = Snd (a,f b) f <$$> x = ($x) <$> f ...
Fst ((,)1,3) <$$> 2 -- no section, don't have the patch ;) Fst ((1,2),3)