tcfail042.hs:16: Context `{PrelBase.Num taHh}' required by inferred type, but missing on a type signature `PrelBase.Num' `taHh' arising from an instance declaration at tcfail042.hs:16 When checking superclass constraints of an instance declaration tcfail042.hs:4: Module Main must include a definition for `Main.main' Compilation had errors