X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcGadt.lhs;h=cbb4230e748952287e090bd309411caf0c1b16fe;hb=940524aec90652b5ef81789c9a453c57c0e42cc9;hp=558f97e063de68ff97945c1e12858187ac30cac6;hpb=b97e1705d4bfd96d6a274d1fe593fff46edd23f6;p=ghc-hetmet.git diff --git a/compiler/typecheck/TcGadt.lhs b/compiler/typecheck/TcGadt.lhs index 558f97e..cbb4230 100644 --- a/compiler/typecheck/TcGadt.lhs +++ b/compiler/typecheck/TcGadt.lhs @@ -1,4 +1,5 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % @@ -10,35 +11,32 @@ \begin{code} module TcGadt ( - Refinement, emptyRefinement, gadtRefine, - refineType, refineResType, - dataConCanMatch, + Refinement, emptyRefinement, isEmptyRefinement, + gadtRefine, + refineType, refinePred, refineResType, tcUnifyTys, BindFlag(..) ) where -import HsSyn ( ExprCoFn(..), idCoercion, isIdCoercion ) -import Coercion ( Coercion, mkSymCoercion, mkTransCoercion, mkUnsafeCoercion, - mkLeftCoercion, mkRightCoercion, mkCoKind, coercionKindPredTy, - splitCoercionKind, decomposeCo, coercionKind ) -import TcType ( TvSubst(..), TvSubstEnv, substTy, mkTvSubst, - substTyVar, zipTopTvSubst, typeKind, - eqKind, isSubKind, repSplitAppTy_maybe, - tcView, tcGetTyVar_maybe - ) -import Type ( Type, tyVarsOfType, tyVarsOfTypes, tcEqType, mkTyVarTy ) -import TypeRep ( Type(..), PredType(..) ) -import DataCon ( DataCon, dataConUnivTyVars, dataConEqSpec ) -import Var ( CoVar, TyVar, tyVarKind, varUnique ) +#include "HsVersions.h" + +import HsSyn +import Coercion +import Type + +import TypeRep +import Var import VarEnv import VarSet -import ErrUtils ( Message ) -import Maybes ( MaybeErr(..), isJust ) -import Control.Monad ( foldM ) +import ErrUtils +import Maybes +import Control.Monad import Outputable -import Unique ( Unique ) -import UniqFM ( ufmToList ) +import TcType -#include "HsVersions.h" +#ifdef DEBUG +import Unique +import UniqFM +#endif \end{code} @@ -50,6 +48,8 @@ import UniqFM ( ufmToList ) \begin{code} data Refinement = Reft InScopeSet InternalReft + +type InternalReft = TyVarEnv (Coercion, Type) -- INVARIANT: a->(co,ty) then co :: (a:=:ty) -- Not necessarily idemopotent @@ -61,30 +61,44 @@ instance Outputable Refinement where emptyRefinement :: Refinement emptyRefinement = (Reft emptyInScopeSet emptyVarEnv) +isEmptyRefinement :: Refinement -> Bool +isEmptyRefinement (Reft _ env) = isEmptyVarEnv env -refineType :: Refinement -> Type -> (ExprCoFn, Type) +refineType :: Refinement -> Type -> Maybe (Coercion, Type) -- Apply the refinement to the type. -- If (refineType r ty) = (co, ty') -- Then co :: ty:=:ty' +-- Nothing => the refinement does nothing to this type refineType (Reft in_scope env) ty | not (isEmptyVarEnv env), -- Common case any (`elemVarEnv` env) (varSetElems (tyVarsOfType ty)) - = (ExprCoFn (substTy co_subst ty), substTy tv_subst ty) + = Just (substTy co_subst ty, substTy tv_subst ty) | otherwise - = (idCoercion, ty) -- The type doesn't mention any refined type variables + = Nothing -- The type doesn't mention any refined type variables where tv_subst = mkTvSubst in_scope (mapVarEnv snd env) co_subst = mkTvSubst in_scope (mapVarEnv fst env) -refineResType :: Refinement -> Type -> (ExprCoFn, Type) +refinePred :: Refinement -> PredType -> Maybe (Coercion, PredType) +refinePred (Reft in_scope env) pred + | not (isEmptyVarEnv env), -- Common case + any (`elemVarEnv` env) (varSetElems (tyVarsOfPred pred)) + = Just (mkPredTy (substPred co_subst pred), substPred tv_subst pred) + | otherwise + = Nothing -- The type doesn't mention any refined type variables + where + tv_subst = mkTvSubst in_scope (mapVarEnv snd env) + co_subst = mkTvSubst in_scope (mapVarEnv fst env) + +refineResType :: Refinement -> Type -> (HsWrapper, Type) -- Like refineType, but returns the 'sym' coercion -- If (refineResType r ty) = (co, ty') -- Then co :: ty':=:ty +-- It's convenient to return a HsWrapper here refineResType reft ty = case refineType reft ty of - (ExprCoFn co, ty1) -> (ExprCoFn (mkSymCoercion co), ty1) - (id_co, ty1) -> ASSERT( isIdCoercion id_co ) - (idCoercion, ty1) + Just (co, ty1) -> (WpCo (mkSymCoercion co), ty1) + Nothing -> (idHsWrapper, ty) \end{code} @@ -141,7 +155,7 @@ gadtRefine (Reft in_scope env1) ex_tvs co_vars -- Precondition: fvs( co_vars ) # env1 -- That is, the kinds of the co_vars are a --- fixed point of the incoming refinement +-- fixed point of the incoming refinement = ASSERT2( not $ any (`elemVarEnv` env1) (varSetElems $ tyVarsOfTypes $ map tyVarKind co_vars), ppr env1 $$ ppr co_vars $$ ppr (map tyVarKind co_vars) ) @@ -159,14 +173,16 @@ gadtRefine (Reft in_scope env1) where tv_set = mkVarSet ex_tvs in_scope' = foldr extend in_scope co_vars + + -- For each co_var, add it *and* the tyvars it mentions, to in_scope extend co_var in_scope - = extendInScopeSetSet (extendInScopeSet in_scope co_var) - (tyVarsOfType (tyVarKind co_var)) + = extendInScopeSetSet in_scope $ + extendVarSet (tyVarsOfType (tyVarKind co_var)) co_var do_one reft co_var = unify reft (TyVarTy co_var) ty1 ty2 where (ty1,ty2) = splitCoercionKind (tyVarKind co_var) -\end{code} +\end{code} %************************************************************************ %* * @@ -208,15 +224,13 @@ fixTvCoEnv in_scope env where fixpt = mapVarEnv step env - step (co, ty) = (co1, ty') + step (co, ty) = case refineType (Reft in_scope fixpt) ty of + Nothing -> (co, ty) + Just (co', ty') -> (mkTransCoercion co co', ty') -- Apply fixpt one step: -- Use refineType to get a substituted type, ty', and a coercion, co_fn, -- which justifies the substitution. If the coercion is not the identity -- then use transitivity with the original coercion - where - (co_fn, ty') = refineType (Reft in_scope fixpt) ty - co1 | ExprCoFn co'' <- co_fn = mkTransCoercion co co'' - | otherwise = ASSERT( isIdCoercion co_fn ) co ----------------------------- fixTvSubstEnv :: InScopeSet -> TvSubstEnv -> TvSubstEnv @@ -226,26 +240,10 @@ fixTvSubstEnv in_scope env fixpt = mapVarEnv (substTy (mkTvSubst in_scope fixpt)) env ---------------------------- -dataConCanMatch :: DataCon -> [Type] -> Bool --- Returns True iff the data con can match a scrutinee of type (T tys) --- where T is the type constructor for the data con --- --- Instantiate the equations and try to unify them -dataConCanMatch con tys - = isJust (tcUnifyTys (\tv -> BindMe) - (map (substTyVar subst . fst) eq_spec) - (map snd eq_spec)) - where - dc_tvs = dataConUnivTyVars con - eq_spec = dataConEqSpec con - subst = zipTopTvSubst dc_tvs tys - ----------------------------- tryToBind :: TyVarSet -> TyVar -> BindFlag tryToBind tv_set tv | tv `elemVarSet` tv_set = BindMe | otherwise = AvoidMe - \end{code} @@ -256,11 +254,7 @@ tryToBind tv_set tv | tv `elemVarSet` tv_set = BindMe %************************************************************************ \begin{code} -type InternalReft = TyVarEnv (Coercion, Type) - --- INVARIANT: a->(co,ty) then co :: (a:=:ty) --- Not necessarily idemopotent - +#ifdef DEBUG badReftElts :: InternalReft -> [(Unique, (Coercion,Type))] -- Return the BAD elements of the refinement -- Should be empty; used in asserions only @@ -273,6 +267,7 @@ badReftElts env | otherwise = False where (ty1,ty2) = coercionKind co +#endif emptyInternalReft :: InternalReft emptyInternalReft = emptyVarEnv @@ -387,8 +382,10 @@ uUnrefined :: Bool -- Whether the input is swapped -> UM InternalReft -- We know that tv1 isn't refined --- PRE-CONDITION: in the call (uUnrefined r co tv ty ty'), we know that --- co :: tv:=:ty +-- PRE-CONDITION: in the call (uUnrefined False r co tv1 ty2 ty2'), we know that +-- co :: tv1:=:ty2 +-- and if the first argument is True instead, we know +-- co :: ty2:=:tv1 uUnrefined swap subst co tv1 ty2 ty2' | Just ty2'' <- tcView ty2' @@ -550,4 +547,4 @@ kindMisMatch tv1 t2 occursCheck tv ty = hang (ptext SLIT("Can't construct the infinite type")) 2 (ppr tv <+> equals <+> ppr ty) -\end{code} \ No newline at end of file +\end{code}