../Plugin.hs:5:31: Couldn't match the rigid variable `a' against `Int' `a' is bound by the polymorphic type `forall a. (Num a) => a -> a -> a' at ../Plugin.hs:5:11-56 Expected type: a -> a -> a Inferred type: Int -> Int -> Int In the expression: (+) :: Int -> Int -> Int In the `function' field of a record