{-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE NoImplicitPrelude #-} module Main where import Prelude (Maybe(..), Show(..), String, Bool(..), print) pattern ReqNoProv :: Show a => a -> Maybe a pattern ReqNoProv{j} = Just j p1 = ReqNoProv True p7 (ReqNoProv _) = ReqNoProv False p6 = p1 {j = False} main = print p6