input.hs

module Main where

f1 :: (Show a, Eq a) => a
f1 a = a

f2 ::
  (Show a
  , Eq a)
  => a
f2 a = a

-- We don't currently realise that the inner tuple type
-- is a constraint tuple.
f3 ::
  ( Generic a
  , (Show a, Num a)
  , Eq a)
  => a
f3 a = a

f4 ::
  (Show a, Num a)
  =>
  Eq a
  => a
f4 a = a

f5 ::
  (Show a
  -- an interloping comment
  , Eq a)
  => a
f5 a = a

class (Show a, Eq a) => Class1 a where

data (Generic a, (Show a, Eq a)) => A a

deriving instance (Show a, Eq a) => Class1 Int

-- We can't know this is a constraint tuple type rather than a normal
-- tuple type without type information
type MyConstraints a = (Show a, Eq a)

-- https://github.com/fourmolu/fourmolu/issues/451
data Foo = forall a. (B, A a) => Foo a