On Thu, Apr 10, 2014 at 10:21 AM, Kim-Ee Yeoh
No problems here:
# ghci GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let whee :: Show a => Eq a => a => Bool; whee x = x == x && null (show x) Prelude> :t whee whee :: (Eq a, Show a) => a -> Bool
It seems to be an issue with giving everything on a single line: $ ghci GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude λ> let whee x = x == x && null (show x) :: Show a => Eq a => a => Bool <interactive>:2:14: Couldn't match expected type `a -> Bool' with actual type `Bool' In the expression: x == x && null (show x) :: Show a => Eq a => a => Bool In an equation for `whee': whee x = x == x && null (show x) :: Show a => Eq a => a => Bool I see now to make it work as a one liner I could do it this way: Prelude λ> :t (\x -> x == x && null (show x)) :: Show a => Eq a => a => Bool (\x -> x == x && null (show x)) :: Show a => Eq a => a => Bool :: (Eq a, Show a) => a -> Bool Thanks!