1 Nov
2010
1 Nov
'10
10:40 p.m.
On Mon, 1 Nov 2010, Andrew Coppin wrote:
The other day, I accidentally came up with this:
{-# LANGUAGE RankNTypes #-}
type Either x y = forall r. (x -> r) -> (y -> r) -> r
left :: x -> Either x y left x f g = f x
right :: y -> Either x y right y f g = g y
This is one example; it seems that just about any algebraic type can be encoded this way. I presume that somebody else has thought of this before. Does it have a name?
http://www.haskell.org/haskellwiki/Functions_not_data_structures The article could be more informative. This was asked several times in Haskell-Cafe, thus it should certainly be Category:FAQ - but with what title?