Hi, superclass.hs myX = 1 :: Int sigmund :: Int -> Int sigmund x = myX prelude> :l superclass.hs [1 of 1] Compiling Main Ok, one module loaded. ================================================================================== superclass.hs myX = 1 :: Int sigmund :: Num -> Num sigmund x = myX prelude> :l superclass.hs typed_checked.hs:3:13: error: • Expecting one more argument to ‘Num’ Expected a type, but ‘Num’ has kind ‘* -> Constraint’ • In the type signature: sigmund :: Num -> Num | 3 | sigmund :: Num -> Num | ^^^ typed_checked.hs:3:20: error: • Expecting one more argument to ‘Num’ Expected a type, but ‘Num’ has kind ‘* -> Constraint’ • In the type signature: sigmund :: Num -> Num =================================================================================== I would think since Num is a superclass of Int defining the type in the superclass would be OK, also in the error message it refers to (see black) what does that refer to? thanks!