On 11-04-27 05:44 PM, serialhex wrote:
in ruby they use what some call "duck typing" if it looks like a duck and quacks like a duck... it's a duck.
Python and Javascript also do duck typing. Haskell does Functor typing. A Functor is something that provides an "fmap" method. List does it, so you can do fmap not [True,False] Maybe also does it, so you can also do fmap not (Just False) Your own data type could also do it. Suppose your data type is (binary tree) data BT a = Z | Y a (BT a) (BT a) deriving Show then you add instance Functor BT where fmap f Z = Z fmap f (Y x t0 t1) = Y (f x) (fmap f t0) (fmap f t1) then BT provides an "fmap" method too, and so you can also do fmap not (Y True (Y False Z Z) Z) If it fmaps like a Functor, it is a Functor. That is Functor typing.