X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FFamInstEnv.lhs;h=65c253914e0025f6094903f55db57398255495cd;hb=27759873a8bd45c487a6e636f7a12c37e87f616f;hp=4f83aba811eaa5da1f191728a989355780c3b4b6;hpb=3b1438a9757639d7f37f10e1237e2369ca0ebe4a;p=ghc-hetmet.git diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs index 4f83aba..65c2539 100644 --- a/compiler/types/FamInstEnv.lhs +++ b/compiler/types/FamInstEnv.lhs @@ -5,13 +5,6 @@ FamInstEnv: Type checked family instance declarations \begin{code} -{-# OPTIONS -w #-} --- The above warning supression flag is a temporary kludge. --- While working on this module you are encouraged to remove it and fix --- any warnings in the module. See --- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings --- for details - module FamInstEnv ( FamInst(..), famInstTyCon, famInstTyVars, pprFamInst, pprFamInstHdr, pprFamInsts, @@ -31,8 +24,6 @@ module FamInstEnv ( import InstEnv import Unify -import TcGadt -import TcType import Type import TypeRep import TyCon @@ -40,12 +31,11 @@ import Coercion import VarSet import Var import Name -import OccName -import SrcLoc import UniqFM import Outputable import Maybes import Util +import FastString import Maybe \end{code} @@ -82,6 +72,7 @@ data FamInst famInstTyCon :: FamInst -> TyCon famInstTyCon = fi_tycon +famInstTyVars :: FamInst -> TyVarSet famInstTyVars = fi_tvs \end{code} @@ -96,16 +87,16 @@ instance Outputable FamInst where pprFamInst :: FamInst -> SDoc pprFamInst famInst = hang (pprFamInstHdr famInst) - 2 (ptext SLIT("--") <+> pprNameLoc (getName famInst)) + 2 (ptext (sLit "--") <+> pprNameLoc (getName famInst)) pprFamInstHdr :: FamInst -> SDoc pprFamInstHdr (FamInst {fi_fam = fam, fi_tys = tys, fi_tycon = tycon}) = pprTyConSort <+> pprHead where - pprHead = pprTypeApp fam (ppr fam) tys - pprTyConSort | isDataTyCon tycon = ptext SLIT("data instance") - | isNewTyCon tycon = ptext SLIT("newtype instance") - | isSynTyCon tycon = ptext SLIT("type instance") + pprHead = pprTypeApp fam tys + pprTyConSort | isDataTyCon tycon = ptext (sLit "data instance") + | isNewTyCon tycon = ptext (sLit "newtype instance") + | isSynTyCon tycon = ptext (sLit "type instance") | otherwise = panic "FamInstEnv.pprFamInstHdr" pprFamInsts :: [FamInst] -> SDoc @@ -227,8 +218,25 @@ desugared to we return the matching instance '(FamInst{.., fi_tycon = :R42T}, Int)'. +Note [Over-saturated matches] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +It's ok to look up an over-saturated type constructor. E.g. + type family F a :: * -> * + type instance F (a,b) = Either (a->b) + +The type instance gives rise to a newtype TyCon (at a higher kind +which you can't do in Haskell!): + newtype FPair a b = FP (Either (a->b)) + +Then looking up (F (Int,Bool) Char) will return a FamInstMatch + (FPair, [Int,Bool,Char]) + +The "extra" type argument [Char] just stays on the end. + + \begin{code} type FamInstMatch = (FamInst, [Type]) -- Matching type instance + -- See Note [Over-saturated matches] lookupFamInstEnv :: FamInstEnvs -> TyCon -> [Type] -- What we are looking for @@ -237,13 +245,23 @@ lookupFamInstEnv (pkg_ie, home_ie) fam tys | not (isOpenTyCon fam) = [] | otherwise - = home_matches ++ pkg_matches + = ASSERT( n_tys >= arity ) -- Family type applications must be saturated + home_matches ++ pkg_matches where rough_tcs = roughMatchTcs tys all_tvs = all isNothing rough_tcs home_matches = lookup home_ie pkg_matches = lookup pkg_ie + -- See Note [Over-saturated matches] + arity = tyConArity fam + n_tys = length tys + extra_tys = drop arity tys + (match_tys, add_extra_tys) + | arity > n_tys = (take arity tys, \res_tys -> res_tys ++ extra_tys) + | otherwise = (tys, \res_tys -> res_tys) + -- The second case is the common one, hence functional representation + -------------- lookup env = case lookupUFM env fam of Nothing -> [] -- No instances for this class @@ -264,8 +282,8 @@ lookupFamInstEnv (pkg_ie, home_ie) fam tys = find rest -- Proper check - | Just subst <- tcMatchTys tpl_tvs tpl_tys tys - = (item, substTyVars subst (tyConTyVars tycon)) : find rest + | Just subst <- tcMatchTys tpl_tvs tpl_tys match_tys + = (item, add_extra_tys $ substTyVars subst (tyConTyVars tycon)) : find rest -- No match => try next | otherwise @@ -322,16 +340,11 @@ lookupFamInstEnvUnify (pkg_ie, home_ie) fam tys ) -- Unification will break badly if the variables overlap -- They shouldn't because we allocate separate uniques for them - case tcUnifyTys bind_fn tpl_tys tys of + case tcUnifyTys instanceBindFun tpl_tys tys of Just subst -> let rep_tys = substTyVars subst (tyConTyVars tycon) in ((item, rep_tys), subst) : find rest Nothing -> find rest - --- See explanation at @InstEnv.bind_fn@. --- -bind_fn tv | isTcTyVar tv && isExistentialTyVar tv = Skolem - | otherwise = BindMe \end{code} %************************************************************************ @@ -342,42 +355,63 @@ bind_fn tv | isTcTyVar tv && isExistentialTyVar tv = Skolem \begin{code} topNormaliseType :: FamInstEnvs - -> Type - -> Maybe (Coercion, Type) + -> Type + -> Maybe (Coercion, Type) --- Get rid of *outermost* (or toplevel) type functions by rewriting them +-- Get rid of *outermost* (or toplevel) +-- * type functions +-- * newtypes +-- using appropriate coercions. -- By "outer" we mean that toplevelNormaliseType guarantees to return -- a type that does not have a reducible redex (F ty1 .. tyn) as its -- outermost form. It *can* return something like (Maybe (F ty)), where -- (F ty) is a redex. -topNormaliseType env ty - | Just ty' <- tcView ty = topNormaliseType env ty' - -topNormaliseType env ty@(TyConApp tc tys) - | isOpenTyCon tc - , (ACo co, ty) <- normaliseType env ty - = Just (co, ty) +-- Its a bit like Type.repType, but handles type families too topNormaliseType env ty - = Nothing + = go [] ty + where + go :: [TyCon] -> Type -> Maybe (Coercion, Type) + go rec_nts ty | Just ty' <- coreView ty -- Expand synonyms + = go rec_nts ty' + + go rec_nts (TyConApp tc tys) -- Expand newtypes + | Just co_con <- newTyConCo_maybe tc -- See Note [Expanding newtypes] + = if tc `elem` rec_nts -- in Type.lhs + then Nothing + else let nt_co = mkTyConApp co_con tys + in add_co nt_co rec_nts' nt_rhs + where + nt_rhs = newTyConInstRhs tc tys + rec_nts' | isRecursiveTyCon tc = tc:rec_nts + | otherwise = rec_nts + + go rec_nts (TyConApp tc tys) -- Expand open tycons + | isOpenTyCon tc + , (ACo co, ty) <- normaliseTcApp env tc tys + = -- The ACo says "something happened" + -- Note that normaliseType fully normalises, but it has do to so + -- to be sure that + add_co co rec_nts ty + + go _ _ = Nothing + + add_co co rec_nts ty + = case go rec_nts ty of + Nothing -> Just (co, ty) + Just (co', ty') -> Just (mkTransCoercion co co', ty') -normaliseType :: FamInstEnvs -- environment with family instances - -> Type -- old type - -> (CoercionI,Type) -- (coercion,new type), where - -- co :: old-type ~ new_type --- Normalise the input type, by eliminating all type-function redexes - -normaliseType env ty - | Just ty' <- coreView ty = normaliseType env ty' - -normaliseType env ty@(TyConApp tyCon tys) - = let -- First normalise the arg types +--------------- +normaliseTcApp :: FamInstEnvs -> TyCon -> [Type] -> (CoercionI, Type) +normaliseTcApp env tc tys + = let -- First normalise the arg types so that they'll match + -- when we lookup in in the instance envt (cois, ntys) = mapAndUnzip (normaliseType env) tys - tycon_coi = mkTyConAppCoI tyCon ntys cois + tycon_coi = mkTyConAppCoI tc ntys cois in -- Now try the top-level redex - case lookupFamInstEnv env tyCon ntys of + case lookupFamInstEnv env tc ntys of -- A matching family instance exists [(fam_inst, tys)] -> (fix_coi, nty) where @@ -390,29 +424,36 @@ normaliseType env ty@(TyConApp tyCon tys) -- No unique matching family instance exists; -- we do not do anything - other -> (tycon_coi, TyConApp tyCon ntys) - - where + _ -> (tycon_coi, TyConApp tc ntys) +--------------- +normaliseType :: FamInstEnvs -- environment with family instances + -> Type -- old type + -> (CoercionI, Type) -- (coercion,new type), where + -- co :: old-type ~ new_type +-- Normalise the input type, by eliminating *all* type-function redexes +-- Returns with IdCo if nothing happens -normaliseType env ty@(AppTy ty1 ty2) - = let (coi1,nty1) = normaliseType env ty1 - (coi2,nty2) = normaliseType env ty2 - in (mkAppTyCoI nty1 coi1 nty2 coi2, AppTy nty1 nty2) -normaliseType env ty@(FunTy ty1 ty2) - = let (coi1,nty1) = normaliseType env ty1 - (coi2,nty2) = normaliseType env ty2 - in (mkFunTyCoI nty1 coi1 nty2 coi2, FunTy nty1 nty2) -normaliseType env ty@(ForAllTy tyvar ty1) - = let (coi,nty1) = normaliseType env ty1 - in (mkForAllTyCoI tyvar coi,ForAllTy tyvar nty1) -normaliseType env ty@(NoteTy note ty1) - = let (coi,nty1) = normaliseType env ty1 - in (mkNoteTyCoI note coi,NoteTy note nty1) -normaliseType env ty@(TyVarTy _) - = (IdCo,ty) +normaliseType env ty + | Just ty' <- coreView ty = normaliseType env ty' +normaliseType env (TyConApp tc tys) + = normaliseTcApp env tc tys +normaliseType env (AppTy ty1 ty2) + = let (coi1,nty1) = normaliseType env ty1 + (coi2,nty2) = normaliseType env ty2 + in (mkAppTyCoI nty1 coi1 nty2 coi2, AppTy nty1 nty2) +normaliseType env (FunTy ty1 ty2) + = let (coi1,nty1) = normaliseType env ty1 + (coi2,nty2) = normaliseType env ty2 + in (mkFunTyCoI nty1 coi1 nty2 coi2, FunTy nty1 nty2) +normaliseType env (ForAllTy tyvar ty1) + = let (coi,nty1) = normaliseType env ty1 + in (mkForAllTyCoI tyvar coi,ForAllTy tyvar nty1) +normaliseType _ ty@(TyVarTy _) + = (IdCo,ty) normaliseType env (PredTy predty) - = normalisePred env predty + = normalisePred env predty +--------------- normalisePred :: FamInstEnvs -> PredType -> (CoercionI,Type) normalisePred env (ClassP cls tys) = let (cois,tys') = mapAndUnzip (normaliseType env) tys