Prelude.List.(++) : List a -> List a -> List a Prelude.Strings.(++) : String -> String -> String a is not an implicit argument of Prelude.Interfaces./ Usage is :doc Usage is :wc Usage is :printdef pat {ty503} : Type toplevel.u. pat {__interface504} : Prelude.Interfaces.Fractional {ty503}. Prelude.Interfaces./ {ty503} {__interface504} : pty {ty503} : Type toplevel.u. pty {__interface504} : Prelude.Interfaces.Fractional {ty503}. {ty503} -> {ty503} -> {ty503} (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