{-# LANGUAGE PolyKinds #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} module T13738 where import Data.Coerce import Data.Proxy foo x = coerce @(forall (a :: k). Proxy a -> Int) @(forall (a :: k). Proxy a -> Int) x