From: http://en.wikibooks.org/wiki/Haskell/Applicative_Functors ============================= import Control.Applicative f :: (a -> b -> c) fmap :: Functor f => (d -> e) -> f d -> f e fmap f :: Functor f => f a -> f (b -> c)    -- Identify d with a, and e with (b -> c) sumsqr :: Int -> Int -> Int    -- my f sumsqr i j = i*i+j*j ============================= I'm trying to understand how the above works but... [michael@localhost ~]$ ghci GHCi, version 6.12.1: http://www.haskell.org/ghc/  :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude> :l bozo.hs [1 of 1] Compiling Main             ( bozo.hs, interpreted ) bozo.hs:5:0: Invalid type signature Failed, modules loaded: none. Prelude> Michael