[Haskell-cafe] Inferred typing?

In the code below, is the type returned by the return functions inferred from the result type in the function type signature, i.e., just change the result type to Maybe Int and the code will return a Maybe monad, (Just 4), instead of a List monad? Michael ========= import Monad fn :: [Int] -> [Int] fn l = mzero `mplus` (return (head l)) `mplus` (return (last l)) ================ *Main> :l test5 [1 of 1] Compiling Main             ( test5.hs, interpreted ) Ok, modules loaded: Main. *Main> fn [4,5,6,7,8] [4,8] *Main>