NamedWildcardsNotInMonotype.hs:5:1: error:
    • Could not deduce (Eq w0)
      from the context: (Show a, Eq w, Eq a)
        bound by the inferred type for ‘foo’:
                   (Show a, Eq w, Eq a) => a -> a -> String
        at NamedWildcardsNotInMonotype.hs:5:1-33
      The type variable ‘w0’ is ambiguous
    • In the ambiguity check for the inferred type for ‘foo’
      To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
      When checking the inferred type
        foo :: forall w a. (Show a, Eq w, Eq a) => a -> a -> String