T10519.hs:5:18: warning: [-Wpartial-type-signatures (in -Wdefault)]
    • Found type wildcard ‘_’ standing for ‘Eq a’
      Where: ‘a’ is a rigid type variable bound by
               the inferred type of foo :: Eq a => a -> a -> Bool
               at T10519.hs:6:1-16
    • In the type signature: foo :: forall a. _ => a -> a -> Bool