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-- test reifyInstances
{-# LANGUAGE TypeFamilies #-}
module TH_reifyInstances where
import System.IO
import Language.Haskell.TH
import Text.PrettyPrint.HughesPJ
-- classes
class C1 a where f1 :: a
class C2 a where f2 :: a
instance C2 Int where f2 = 0
instance C2 Bool where f2 = True
-- type families
type family T1 a
type family T2 a
type instance T2 Int = Char
type instance T2 Bool = Int
-- data families
data family D1 a
data family D2 a
data instance D2 Int = DInt | DInt2
data instance D2 Bool = DBool
$(return [])
test :: ()
test = $(let
display :: Name -> Q ()
display n = do
{ intTy <- [t| Int |]
; is1 <- reifyInstances n [intTy]
; runIO $ hPutStrLn stderr (nameBase n)
; runIO $ hPutStrLn stderr (pprint is1)
}
in do { display ''C1
; display ''C2
; display ''T1
; display ''T2
; display ''D1
; display ''D2
; [| () |]
})
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