Leary: I don't think that idea works, GHC warns: /home/pgujjula/temp/eq1-example/app/Main.hs:18:10: warning: [-Wmissing-methods] • No explicit implementation for either ‘==’ or ‘/=’ • In the instance declaration for ‘Eq (F1 f a)’ | 18 | instance (Eq1 f, Eq a) => Eq (F1 f a) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Ok, one module loaded. and "func" hangs as a result