Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/tests/conformance98/fields/type/Main.hs
data Foo a = Foo { foo :: a , bar :: Int } deriving Show up s t = s { foo = t } obj = Foo { foo = 1 :: Int , bar = 99 } main = print ( obj , up obj () , obj {foo=True} )