blob: 856da7cae7932e53b9f65e0fde3fbefffc67832e (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
|
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE RankNTypes #-}
module T19360 where
import GHC.Exts (oneShot)
import Data.Typeable (Typeable, cast)
newtype SDoc = SDoc' (Bool -> Bool)
data EpAnn = EpAnn
showAstData :: D a => Bool -> a -> SDoc
showAstData z = showAstData'
where
showAstData' :: D a => a -> SDoc
showAstData' x =
case cast x of
Just (a :: EpAnn) ->
case z of
True -> showAstData' a
False -> SDoc' (oneShot (\_ -> False))
Nothing -> gmapQr showAstData' x
class Typeable a => D a where
gmapQr :: forall r. (forall d. D d => d -> r) -> a -> r
instance D EpAnn where
gmapQr g EpAnn = g EpAnn
|
