Prelude.List.(++) : List a -> List a -> List a Prelude.Strings.(++) : String -> String -> String (input):1:11:a is not an implicit argument of Prelude.Interfaces./ Usage is :doc Usage is :wc Usage is :printdef pat {ty_503} : Type toplevel.u. pat {__interface_504} : Prelude.Interfaces.Fractional {ty_503}. Prelude.Interfaces./ {ty_503} {__interface_504} : pty {ty_503} : Type toplevel.u. pty {__interface_504} : Prelude.Interfaces.Fractional {ty_503}. {ty_503} -> {ty_503} -> {ty_503} (input):1:1: error: expected: ":", dependent type signature, end of input / ^ (input):1:1: error: expected: ":", dependent type signature, end of input ++ ^ Can't find implementation for Fractional ty