struct Id a =
    id :: a -> a
 
struct Any < Id a

struct Any2 < Id a =
    extra :: Int

s1 = struct id x = x

s2 = struct id x = 'a':x

s3 = struct id x = x; extra = 2

-- bad1 = struct id x = 'a':x ; extra = 2

ok1 y = if y.extra == 1 then y.id ('a':) "" else y.id ""

-- bad2 = \y -> if True then y.id ('a':) "" else y.id ""

ok2 :: Any2 -> String
ok2 y = if True then y.id ('a':) "" else y.id ""