6 Mar
2009
6 Mar
'09
10:39 p.m.
Given the following (usual) definition of "map": map :: (a -> b) -> [a] -> [b] map f [] = [] map f (x : xs) = f x : map f xs What's the type of "map map"? GHCi's :t command reveals: *Main> :t map map map map :: [a -> b] -> [[a] -> [b]] I'd be grateful if anyone could provide a systematic type calculation so that I can reason through more complicated examples myself. Thanks. _________________________________________________________________ Windows Live™: Life without walls. http://windowslive.com/explore?ocid=TXT_TAGLM_WL_allup_1a_explore_032009