module Generics.Regular.TH
( deriveAll,
deriveConstructors,
deriveSelectors,
deriveRegular,
derivePF
) where
import Data.List (intercalate)
import Generics.Regular.Base
import Generics.Regular.Constructor
import Language.Haskell.TH hiding (Fixity())
import Language.Haskell.TH.Syntax (Lift(..))
import Control.Monad
deriveAll :: Name -> String -> Q [Dec]
deriveAll n s =
do a <- deriveConstructors n
b <- deriveSelectors n
c <- deriveRegular n s
return (a ++ b ++ c)
deriveConstructors :: Name -> Q [Dec]
deriveConstructors = constrInstance
deriveSelectors :: Name -> Q [Dec]
deriveSelectors = selectInstance
deriveRegular :: Name -> String -> Q [Dec]
deriveRegular n pfn =
do
pf <- derivePF pfn n
fam <- deriveInst n
return $ pf ++ fam
derivePF :: String -> Name -> Q [Dec]
derivePF pfn n =
do
i <- reify n
fmap (:[]) $ tySynD (mkName pfn) (typeVariables i) (pfType n)
deriveInst :: Name -> Q [Dec]
deriveInst t =
do
i <- reify t
let typ = foldl (\a -> AppT a . VarT . tyVarBndrToName) (ConT t) (typeVariables i)
fcs <- mkFrom t 1 0 t
tcs <- mkTo t 1 0 t
liftM (:[]) $
instanceD (cxt []) (conT ''Regular `appT` return typ)
[funD 'from fcs, funD 'to tcs]
constrInstance :: Name -> Q [Dec]
constrInstance n =
do
i <- reify n
case i of
TyConI (DataD _ n _ cs _) -> mkInstance n cs
TyConI (NewtypeD _ n _ c _) -> mkInstance n [c]
_ -> return []
where
mkInstance n cs = do
ds <- mapM (mkConstrData n) cs
is <- mapM (mkConstrInstance n) cs
return $ ds ++ is
selectInstance :: Name -> Q [Dec]
selectInstance n =
do
i <- reify n
case i of
TyConI (DataD _ n _ cs _) -> mkInstance n cs
TyConI (NewtypeD _ n _ c _) -> mkInstance n [c]
_ -> return []
where
mkInstance n cs = do
ds <- mapM (mkSelectData n) cs
is <- mapM (mkSelectInstance n) cs
return $ concat (ds ++ is)
#ifdef TH_TYVARBNDR
typeVariables :: Info -> [TyVarBndr]
#else
typeVariables :: Info -> [Name]
#endif
typeVariables (TyConI (DataD _ _ tv _ _)) = tv
typeVariables (TyConI (NewtypeD _ _ tv _ _)) = tv
typeVariables _ = []
#ifdef TH_TYVARBNDR
tyVarBndrToName :: TyVarBndr -> Name
tyVarBndrToName (PlainTV name) = name
tyVarBndrToName (KindedTV name _) = name
#else
tyVarBndrToName :: Name -> Name
tyVarBndrToName = id
#endif
stripRecordNames :: Con -> Con
stripRecordNames (RecC n f) =
NormalC n (map (\(_, s, t) -> (s, t)) f)
stripRecordNames c = c
genName :: [Name] -> Name
genName = mkName . (++"_") . intercalate "_" . map nameBase
mkConstrData :: Name -> Con -> Q Dec
mkConstrData dt (NormalC n _) =
dataD (cxt []) (genName [dt, n]) [] [] []
mkConstrData dt r@(RecC _ _) =
mkConstrData dt (stripRecordNames r)
mkConstrData dt (InfixC t1 n t2) =
mkConstrData dt (NormalC n [t1,t2])
mkSelectData :: Name -> Con -> Q [Dec]
mkSelectData dt r@(RecC n fs) = return (map one fs)
where one (f, _, _) = DataD [] (genName [dt, n, f]) [] [] []
mkSelectData dt _ = return []
instance Lift Fixity where
lift Prefix = conE 'Prefix
lift (Infix a n) = conE 'Infix `appE` [| a |] `appE` [| n |]
instance Lift Associativity where
lift LeftAssociative = conE 'LeftAssociative
lift RightAssociative = conE 'RightAssociative
lift NotAssociative = conE 'NotAssociative
mkConstrInstance :: Name -> Con -> Q Dec
mkConstrInstance dt (NormalC n _) = mkConstrInstanceWith dt n []
mkConstrInstance dt (RecC n _) = mkConstrInstanceWith dt n
[ funD 'conIsRecord [clause [wildP] (normalB (conE 'True)) []]]
mkConstrInstance dt (InfixC t1 n t2) =
do
i <- reify n
let fi = case i of
DataConI _ _ _ f -> convertFixity f
_ -> Prefix
instanceD (cxt []) (appT (conT ''Constructor) (conT $ genName [dt, n]))
[funD 'conName [clause [wildP] (normalB (stringE (nameBase n))) []],
funD 'conFixity [clause [wildP] (normalB [| fi |]) []]]
where
convertFixity (Fixity n d) = Infix (convertDirection d) n
convertDirection InfixL = LeftAssociative
convertDirection InfixR = RightAssociative
convertDirection InfixN = NotAssociative
mkConstrInstanceWith :: Name -> Name -> [Q Dec] -> Q Dec
mkConstrInstanceWith dt n extra =
instanceD (cxt []) (appT (conT ''Constructor) (conT $ genName [dt, n]))
(funD 'conName [clause [wildP] (normalB (stringE (nameBase n))) []] : extra)
mkSelectInstance :: Name -> Con -> Q [Dec]
mkSelectInstance dt r@(RecC n fs) = return (map one fs)
where
one (f, _, _) =
InstanceD ([]) (AppT (ConT ''Selector) (ConT $ genName [dt, n, f]))
[FunD 'selName [Clause [WildP] (NormalB (LitE (StringL (nameBase f)))) []]]
mkSelectInstance _ _ = return []
pfType :: Name -> Q Type
pfType n =
do
i <- reify n
let b = case i of
TyConI (DataD _ dt vs cs _) ->
foldr1 sum (map (pfCon (dt, map tyVarBndrToName vs)) cs)
TyConI (NewtypeD _ dt vs c _) ->
pfCon (dt, map tyVarBndrToName vs) c
TyConI (TySynD t _ _) ->
conT ''K `appT` conT t
_ -> error "unknown construct"
b
where
sum :: Q Type -> Q Type -> Q Type
sum a b = conT ''(:+:) `appT` a `appT` b
pfCon :: (Name, [Name]) -> Con -> Q Type
pfCon (dt, vs) (NormalC n []) =
appT (appT (conT ''C) (conT $ genName [dt, n])) (conT ''U)
pfCon (dt, vs) (NormalC n fs) =
appT (appT (conT ''C) (conT $ genName [dt, n])) (foldr1 prod (map (pfField (dt, vs) . snd) fs))
where
prod :: Q Type -> Q Type -> Q Type
prod a b = conT ''(:*:) `appT` a `appT` b
pfCon (dt, vs) r@(RecC n []) =
appT (appT (conT ''C) (conT $ genName [dt, n])) (conT ''U)
pfCon (dt, vs) r@(RecC n fs) =
appT (appT (conT ''C) (conT $ genName [dt, n])) (foldr1 prod (map (pfField' (dt, vs) n) fs))
where
prod :: Q Type -> Q Type -> Q Type
prod a b = conT ''(:*:) `appT` a `appT` b
pfCon d (InfixC t1 n t2) =
pfCon d (NormalC n [t1,t2])
dataDeclToType :: (Name, [Name]) -> Type
dataDeclToType (dt, vs) = foldl (\a b -> AppT a (VarT b)) (ConT dt) vs
pfField :: (Name, [Name]) -> Type -> Q Type
pfField d t | t == dataDeclToType d = conT ''I
pfField d t = conT ''K `appT` return t
pfField' :: (Name, [Name]) -> Name -> (Name, Strict, Type) -> Q Type
pfField' d@(dt, vs) ns (f, _, t) | t == dataDeclToType d = conT ''S `appT` conT (genName [dt, ns, f]) `appT` conT ''I
pfField' (dt, vs) ns (f, _, t) = conT ''S `appT` conT (genName [dt, ns, f]) `appT` (conT ''K `appT` return t)
mkFrom :: Name -> Int -> Int -> Name -> Q [Q Clause]
mkFrom ns m i n =
do
let wrapE e = lrE m i e
i <- reify n
let b = case i of
TyConI (DataD _ dt vs cs _) ->
zipWith (fromCon wrapE ns (dt, map tyVarBndrToName vs) (length cs)) [0..] cs
TyConI (NewtypeD _ dt vs c _) ->
[fromCon wrapE ns (dt, map tyVarBndrToName vs) 1 0 c]
TyConI (TySynD t _ _) ->
[clause [varP (field 0)] (normalB (wrapE $ conE 'K `appE` varE (field 0))) []]
_ -> error "unknown construct"
return b
mkTo :: Name -> Int -> Int -> Name -> Q [Q Clause]
mkTo ns m i n =
do
let wrapP p = lrP m i p
i <- reify n
let b = case i of
TyConI (DataD _ dt vs cs _) ->
zipWith (toCon wrapP ns (dt, map tyVarBndrToName vs) (length cs)) [0..] cs
TyConI (NewtypeD _ dt vs c _) ->
[toCon wrapP ns (dt, map tyVarBndrToName vs) 1 0 c]
TyConI (TySynD t _ _) ->
[clause [wrapP $ conP 'K [varP (field 0)]] (normalB $ varE (field 0)) []]
_ -> error "unknown construct"
return b
fromCon :: (Q Exp -> Q Exp) -> Name -> (Name, [Name]) -> Int -> Int -> Con -> Q Clause
fromCon wrap ns (dt, vs) m i (NormalC cn []) =
clause
[conP cn []]
(normalB $ wrap $ lrE m i $ conE 'C `appE` (conE 'U)) []
fromCon wrap ns (dt, vs) m i (NormalC cn fs) =
clause
[conP cn (map (varP . field) [0..length fs 1])]
(normalB $ wrap $ lrE m i $ conE 'C `appE` foldr1 prod (zipWith (fromField (dt, vs)) [0..] (map snd fs))) []
where
prod x y = conE '(:*:) `appE` x `appE` y
fromCon wrap ns (dt, vs) m i r@(RecC cn []) =
clause
[conP cn []]
(normalB $ wrap $ lrE m i $ conE 'C `appE` (conE 'U)) []
fromCon wrap ns (dt, vs) m i r@(RecC cn fs) =
clause
[conP cn (map (varP . field) [0..length fs 1])]
(normalB $ wrap $ lrE m i $ conE 'C `appE` foldr1 prod (zipWith (fromField' (dt, vs)) [0..] fs)) []
where
prod x y = conE '(:*:) `appE` x `appE` y
fromCon wrap ns (dt, vs) m i (InfixC t1 cn t2) =
fromCon wrap ns (dt, vs) m i (NormalC cn [t1,t2])
fromField :: (Name, [Name]) -> Int -> Type -> Q Exp
fromField (dt, vs) nr t | t == dataDeclToType (dt, vs) = conE 'I `appE` varE (field nr)
fromField (dt, vs) nr t = conE 'K `appE` varE (field nr)
fromField' :: (Name, [Name]) -> Int -> (Name, Strict, Type) -> Q Exp
fromField' (dt, vs) nr (_, _, t) | t == dataDeclToType (dt, vs) = conE 'S `appE` (conE 'I `appE` varE (field nr))
fromField' (dt, vs) nr (_, _, t) = conE 'S `appE` (conE 'K `appE` varE (field nr))
toCon :: (Q Pat -> Q Pat) -> Name -> (Name, [Name]) -> Int -> Int -> Con -> Q Clause
toCon wrap ns (dt, vs) m i (NormalC cn []) =
clause
[wrap $ lrP m i $ conP 'C [conP 'U []]]
(normalB $ conE cn) []
toCon wrap ns (dt, vs) m i (NormalC cn fs) =
clause
[wrap $ lrP m i $ conP 'C [foldr1 prod (zipWith (toField (dt, vs)) [0..] (map snd fs))]]
(normalB $ foldl appE (conE cn) (map (varE . field) [0..length fs 1])) []
where
prod x y = conP '(:*:) [x,y]
toCon wrap ns (dt, vs) m i r@(RecC cn []) =
clause
[wrap $ lrP m i $ conP 'C [conP 'U []]]
(normalB $ conE cn) []
toCon wrap ns (dt, vs) m i r@(RecC cn fs) =
clause
[wrap $ lrP m i $ conP 'C [foldr1 prod (zipWith (toField' (dt, vs)) [0..] fs)]]
(normalB $ foldl appE (conE cn) (map (varE . field) [0..length fs 1])) []
where
prod x y = conP '(:*:) [x,y]
toCon wrap ns (dt, vs) m i (InfixC t1 cn t2) =
toCon wrap ns (dt, vs) m i (NormalC cn [t1,t2])
toField :: (Name, [Name]) -> Int -> Type -> Q Pat
toField (dt, vs) nr t | t == dataDeclToType (dt, vs) = conP 'I [varP (field nr)]
toField (dt, vs) nr t = conP 'K [varP (field nr)]
toField' :: (Name, [Name]) -> Int -> (Name, Strict, Type) -> Q Pat
toField' (dt, vs) nr (_, _, t) | t == dataDeclToType (dt, vs) = conP 'S [conP 'I [varP (field nr)]]
toField' (dt, vs) nr (_, _, t) = conP 'S [conP 'K [varP (field nr)]]
field :: Int -> Name
field n = mkName $ "f" ++ show n
lrP :: Int -> Int -> (Q Pat -> Q Pat)
lrP 1 0 p = p
lrP m 0 p = conP 'L [p]
lrP m i p = conP 'R [lrP (m1) (i1) p]
lrE :: Int -> Int -> (Q Exp -> Q Exp)
lrE 1 0 e = e
lrE m 0 e = conE 'L `appE` e
lrE m i e = conE 'R `appE` lrE (m1) (i1) e