T3540.hs:4:12: error:
    Constraint ‘a ~ Int’ used as a type
    In the type signature for ‘thing’: thing :: a ~ Int

T3540.hs:7:20: error:
    Constraint ‘a ~ Int’ used as a type
    In the type signature for ‘thing1’: thing1 :: Int -> (a ~ Int)

T3540.hs:10:13: error:
    Constraint ‘a ~ Int’ used as a type
    In the type signature for ‘thing2’: thing2 :: (a ~ Int) -> Int

T3540.hs:13:12: error:
    Constraint ‘?dude :: Int’ used as a type
    In the type signature for ‘thing3’: thing3 :: (?dude :: Int) -> Int

T3540.hs:16:11: error:
    Constraint ‘Eq a’ used as a type
    In the type signature for ‘thing4’: thing4 :: (Eq a) -> Int