無名関数にShowのメソッドを定義するとかやりたくないんだが、どうするべきなのか。
/tmp% ghci GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer ... linking ... done. Loading package base ... linking ... done. Prelude> [ ( \x -> x*x ) , ( \x -> x*x*x )] <interactive>:1:0: No instance for (Show (a -> a)) arising from a use of `print' at <interactive>:1:0-33 Possible fix: add an instance declaration for (Show (a -> a)) In a stmt of a 'do' expression: print it Prelude> length [ ( \x -> x*x ) , ( \x -> x*x*x )] 2 Prelude> map (\f -> (f(2))) [ ( \x -> x*x ) , ( \x -> x*x*x )] [4,8]