allow build settings to be overriden by adding mk/validate.mk

[ghc-hetmet.git] / compiler / types / FamInstEnv.lhs

diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs
index 60b55d1..7c06555 100644 (file)
--- a/compiler/types/FamInstEnv.lhs
+++ b/compiler/types/FamInstEnv.lhs
@@ -10,11 +10,14 @@ module FamInstEnv (
        pprFamInst, pprFamInstHdr, pprFamInsts, 
        famInstHead, mkLocalFamInst, mkImportedFamInst,
 
        pprFamInst, pprFamInstHdr, pprFamInsts, 
        famInstHead, mkLocalFamInst, mkImportedFamInst,
 

-       FamInstEnvs, FamInstEnv, emptyFamInstEnv, 
+       FamInstEnvs, FamInstEnv, emptyFamInstEnv, emptyFamInstEnvs, 

        extendFamInstEnv, extendFamInstEnvList, 
        famInstEnvElts, familyInstances,
 
        extendFamInstEnv, extendFamInstEnvList, 
        famInstEnvElts, familyInstances,
 

-       lookupFamInstEnv, lookupFamInstEnvUnify
+       lookupFamInstEnv, lookupFamInstEnvUnify,
+       
+       -- Normalisation
+       topNormaliseType

     ) where
 
 #include "HsVersions.h"
     ) where
 
 #include "HsVersions.h"

@@ -24,7 +27,9 @@ import Unify
 import TcGadt
 import TcType
 import Type
 import TcGadt
 import TcType
 import Type

+import TypeRep

 import TyCon
 import TyCon

+import Coercion

 import VarSet
 import Var
 import Name
 import VarSet
 import Var
 import Name

@@ -32,6 +37,8 @@ import OccName
 import SrcLoc
 import UniqFM
 import Outputable
 import SrcLoc
 import UniqFM
 import Outputable

+import Maybes
+import Util

 
 import Maybe
 \end{code}
 
 import Maybe
 \end{code}

@@ -51,7 +58,7 @@ data FamInst
 
                -- Used for "rough matching"; same idea as for class instances
            , fi_tcs   :: [Maybe Name]  -- Top of type args
 
                -- Used for "rough matching"; same idea as for class instances
            , fi_tcs   :: [Maybe Name]  -- Top of type args

-               -- INVARIANT: fi_tcs = roughMatchTcs is_tys
+               -- INVARIANT: fi_tcs = roughMatchTcs fi_tys

 
                -- Used for "proper matching"; ditto
            , fi_tvs   :: TyVarSet      -- Template tyvars for full match
 
                -- Used for "proper matching"; ditto
            , fi_tvs   :: TyVarSet      -- Template tyvars for full match

@@ -82,13 +89,13 @@ instance Outputable FamInst where
 pprFamInst :: FamInst -> SDoc
 pprFamInst famInst
   = hang (pprFamInstHdr famInst)
 pprFamInst :: FamInst -> SDoc
 pprFamInst famInst
   = hang (pprFamInstHdr famInst)

-       2 (ptext SLIT("--") <+> (pprDefnLoc (getSrcLoc famInst)))
+       2 (ptext SLIT("--") <+> (pprDefnLoc (getSrcSpan famInst)))

 
 pprFamInstHdr :: FamInst -> SDoc
 pprFamInstHdr (FamInst {fi_fam = fam, fi_tys = tys, fi_tycon = tycon})
   = pprTyConSort <+> pprHead
   where
 
 pprFamInstHdr :: FamInst -> SDoc
 pprFamInstHdr (FamInst {fi_fam = fam, fi_tys = tys, fi_tycon = tycon})
   = pprTyConSort <+> pprHead
   where

-    pprHead = pprTypeApp (parenSymOcc (getOccName fam) (ppr fam)) tys
+    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")
     pprTyConSort | isDataTyCon tycon = ptext SLIT("data instance")
                 | isNewTyCon  tycon = ptext SLIT("newtype instance")
                 | isSynTyCon  tycon = ptext SLIT("type instance")

@@ -161,6 +168,9 @@ data FamilyInstEnv
 --  * The fs_tvs are distinct in each FamInst
 --     of a range value of the map (so we can safely unify them)
 
 --  * The fs_tvs are distinct in each FamInst
 --     of a range value of the map (so we can safely unify them)
 

+emptyFamInstEnvs :: (FamInstEnv, FamInstEnv)
+emptyFamInstEnvs = (emptyFamInstEnv, emptyFamInstEnv)
+

 emptyFamInstEnv :: FamInstEnv
 emptyFamInstEnv = emptyUFM
 
 emptyFamInstEnv :: FamInstEnv
 emptyFamInstEnv = emptyUFM
 

@@ -189,7 +199,7 @@ extendFamInstEnv inst_env ins_item@(FamInst {fi_fam = cls_nm, fi_tcs = mb_tcs})
 
 %************************************************************************
 %*                                                                     *
 
 %************************************************************************
 %*                                                                     *

-\subsection{Looking up a family instance}
+               Looking up a family instance

 %*                                                                     *
 %************************************************************************
 
 %*                                                                     *
 %************************************************************************
 

@@ -198,11 +208,28 @@ Multiple matches are only possible in case of type families (not data
 families), and then, it doesn't matter which match we choose (as the
 instances are guaranteed confluent).
 
 families), and then, it doesn't matter which match we choose (as the
 instances are guaranteed confluent).
 

+We return the matching family instances and the type instance at which it
+matches.  For example, if we lookup 'T [Int]' and have a family instance
+
+  data instance T [a] = ..
+
+desugared to
+
+  data :R42T a = ..
+  coe :Co:R42T a :: T [a] ~ :R42T a
+
+we return the matching instance '(FamInst{.., fi_tycon = :R42T}, Int)'.
+

 \begin{code}
 \begin{code}

+type FamInstMatch = (FamInst, [Type])           -- Matching type instance
+

 lookupFamInstEnv :: FamInstEnvs
                 -> TyCon -> [Type]             -- What we are looking for
 lookupFamInstEnv :: FamInstEnvs
                 -> TyCon -> [Type]             -- What we are looking for

-                -> [(TvSubst, FamInst)]        -- Successful matches
+                -> [FamInstMatch]              -- Successful matches

 lookupFamInstEnv (pkg_ie, home_ie) fam tys
 lookupFamInstEnv (pkg_ie, home_ie) fam tys

+  | not (isOpenTyCon fam) 
+  = []
+  | otherwise

   = home_matches ++ pkg_matches
   where
     rough_tcs    = roughMatchTcs tys
   = home_matches ++ pkg_matches
   where
     rough_tcs    = roughMatchTcs tys

@@ -231,7 +258,7 @@ lookupFamInstEnv (pkg_ie, home_ie) fam tys
 
         -- Proper check
       | Just subst <- tcMatchTys tpl_tvs tpl_tys tys
 
         -- Proper check
       | Just subst <- tcMatchTys tpl_tvs tpl_tys tys

-      = (subst, item) : find rest
+      = (item, substTyVars subst (tyConTyVars tycon)) : find rest

 
         -- No match => try next
       | otherwise
 
         -- No match => try next
       | otherwise

@@ -250,8 +277,11 @@ indexed synonyms and we don't want to slow that down by needless unification.
 
 \begin{code}
 lookupFamInstEnvUnify :: (FamInstEnv, FamInstEnv) -> TyCon -> [Type]
 
 \begin{code}
 lookupFamInstEnvUnify :: (FamInstEnv, FamInstEnv) -> TyCon -> [Type]

-                     -> [(TvSubst, FamInst)]
+                     -> [(FamInstMatch, TvSubst)]

 lookupFamInstEnvUnify (pkg_ie, home_ie) fam tys
 lookupFamInstEnvUnify (pkg_ie, home_ie) fam tys

+  | not (isOpenTyCon fam) 
+  = []
+  | otherwise

   = home_matches ++ pkg_matches
   where
     rough_tcs    = roughMatchTcs tys
   = home_matches ++ pkg_matches
   where
     rough_tcs    = roughMatchTcs tys

@@ -286,7 +316,9 @@ 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
                -- 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

-           Just subst -> (subst, item) : find rest
+           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@.
            Nothing    -> find rest
 
 -- See explanation at @InstEnv.bind_fn@.

@@ -294,3 +326,95 @@ lookupFamInstEnvUnify (pkg_ie, home_ie) fam tys
 bind_fn tv | isTcTyVar tv && isExistentialTyVar tv = Skolem
           | otherwise                             = BindMe
 \end{code}
 bind_fn tv | isTcTyVar tv && isExistentialTyVar tv = Skolem
           | otherwise                             = BindMe
 \end{code}

+
+%************************************************************************
+%*                                                                     *
+               Looking up a family instance
+%*                                                                     *
+%************************************************************************
+
+\begin{code}
+topNormaliseType :: FamInstEnvs
+                     -> Type
+                     -> Maybe (Coercion, Type)
+
+-- Get rid of *outermost* (or toplevel) type functions by rewriting them
+-- 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)
+
+topNormaliseType env ty
+  = Nothing
+        
+
+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
+       (cois, ntys) = mapAndUnzip (normaliseType env) tys
+       tycon_coi    = mkTyConAppCoI tyCon ntys cois
+    in         -- Now try the top-level redex
+    case lookupFamInstEnv env tyCon ntys of
+               -- A matching family instance exists
+       [(fam_inst, tys)] -> (fix_coi, nty)
+           where
+               rep_tc         = famInstTyCon fam_inst
+               co_tycon       = expectJust "lookupFamInst" (tyConFamilyCoercion_maybe rep_tc)
+               co             = mkTyConApp co_tycon tys
+               first_coi      = mkTransCoI tycon_coi (ACo co)
+               (rest_coi,nty) = normaliseType env (mkTyConApp rep_tc tys)
+               fix_coi        = mkTransCoI first_coi rest_coi
+
+               -- No unique matching family instance exists;
+               -- we do not do anything
+       other -> (tycon_coi, TyConApp tyCon ntys)
+
+  where
+
+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 (PredTy predty)
+  =    normalisePred env predty        
+
+normalisePred :: FamInstEnvs -> PredType -> (CoercionI,Type)
+normalisePred env (ClassP cls tys)
+  =    let (cois,tys') = mapAndUnzip (normaliseType env) tys
+       in  (mkClassPPredCoI cls tys' cois, PredTy $ ClassP cls tys')
+normalisePred env (IParam ipn ty)
+  =    let (coi,ty') = normaliseType env ty
+       in  (mkIParamPredCoI ipn coi, PredTy $ IParam ipn ty')
+normalisePred env (EqPred ty1 ty2)
+  =    let (coi1,ty1') = normaliseType env ty1
+            (coi2,ty2') = normaliseType env ty2
+       in  (mkEqPredCoI ty1' coi1 ty2' coi2, PredTy $ EqPred ty1' ty2')
+\end{code}