import CoreUnfold ( isCheapUnfolding, unfoldingTemplate )
import CoreUtils ( eqExpr )
import CoreTidy ( pprTidyIdRules )
-import Subst ( Subst, InScopeSet, mkInScopeSet, lookupSubst, extendSubst,
- substEnv, setSubstEnv, emptySubst, isInScope, emptyInScopeSet,
- bindSubstList, unBindSubstList, substInScope, uniqAway
+import Subst ( Subst, SubstResult(..), extendIdSubst,
+ getTvSubstEnv, setTvSubstEnv,
+ emptySubst, isInScope, lookupIdSubst, lookupTvSubst,
+ bindSubstList, unBindSubstList, substInScope
)
import Id ( Id, idUnfolding, idSpecialisation, setIdSpecialisation )
-import Var ( isId )
+import Var ( Var, isId )
import VarSet
import VarEnv
import TcType ( mkTyVarTy )
-import qualified TcType ( match )
+import qualified Unify ( matchTyX )
import BasicTypes ( Activation, CompilerPhase, isActive )
import Outputable
-----------------------
app_match subst fn vs = foldl go fn vs
- where
- senv = substEnv subst
- go fn v = case lookupSubstEnv senv v of
- Just (DoneEx ex) -> fn `App` ex
- Just (DoneTy ty) -> fn `App` Type ty
- -- Substitution should bind them all!
-
+ where
+ go fn v = case lookupVar subst v of
+ Just e -> fn `App` e
+ Nothing -> pprPanic "app_match: unbound tpl" (ppr v)
+
+lookupVar :: Subst -> Var -> Maybe CoreExpr
+lookupVar subst v
+ | isId v = case lookupIdSubst subst v of
+ Just (DoneEx ex) -> Just ex
+ other -> Nothing
+ | otherwise = case lookupTvSubst subst v of
+ Just ty -> Just (Type ty)
+ Nothing -> Nothing
-----------------------
{- The code below tries to match even if there are more
-> Subst -> Maybe result -- Substitution so far -> result
-- The *SubstEnv* in these Substs apply to the TEMPLATE only
--- The *InScopeSet* in these Substs gives variables bound so far in the
+-- The *InScopeSet* in these Substs is HIJACKED,
+-- to give the set of variables bound so far in the
-- target term. So when matching forall a. (\x. a x) against (\y. y y)
-- while processing the body of the lambdas, the in-scope set will be {y}.
-- That lets us do the occurs-check when matching 'a' against 'y'
+--
+-- It starts off empty
match :: CoreExpr -- Template
-> CoreExpr -- Target
match_fail = Nothing
-match (Var v1) e2 tpl_vars kont subst
- = case lookupSubst subst v1 of
+-- ToDo: remove this debugging junk
+-- match e1 e2 tpls kont subst = pprTrace "match" (ppr e1 <+> ppr e2 <+> ppr subst) $ match_ e1 e2 tpls kont subst
+match = match_
+
+match_ (Var v1) e2 tpl_vars kont subst
+ = case lookupIdSubst subst v1 of
Nothing | v1 `elemVarSet` tpl_vars -- v1 is a template variable
-> if (any (`isInScope` subst) (varSetElems (exprFreeVars e2))) then
match_fail -- Occurs check failure
-- e.g. match forall a. (\x-> a x) against (\y. y y)
else
- kont (extendSubst subst v1 (DoneEx e2))
+ kont (extendIdSubst subst v1 (DoneEx e2))
| eqExpr (Var v1) e2 -> kont subst
other -> match_fail
-match (Lit lit1) (Lit lit2) tpl_vars kont subst
+match_ (Lit lit1) (Lit lit2) tpl_vars kont subst
| lit1 == lit2
= kont subst
-match (App f1 a1) (App f2 a2) tpl_vars kont subst
+match_ (App f1 a1) (App f2 a2) tpl_vars kont subst
= match f1 f2 tpl_vars (match a1 a2 tpl_vars kont) subst
-match (Lam x1 e1) (Lam x2 e2) tpl_vars kont subst
+match_ (Lam x1 e1) (Lam x2 e2) tpl_vars kont subst
= bind [x1] [x2] (match e1 e2) tpl_vars kont subst
-- This rule does eta expansion
-- (\x.M) ~ N iff M ~ N x
-- See assumption A3
-match (Lam x1 e1) e2 tpl_vars kont subst
+match_ (Lam x1 e1) e2 tpl_vars kont subst
= bind [x1] [x1] (match e1 (App e2 (mkVarArg x1))) tpl_vars kont subst
-- Eta expansion the other way
-- M ~ (\y.N) iff \y.M y ~ \y.N
-- iff M y ~ N
-- Remembering that by (A), y can't be free in M, we get this
-match e1 (Lam x2 e2) tpl_vars kont subst
+match_ e1 (Lam x2 e2) tpl_vars kont subst
+ | new_id == x2 -- If the two are equal, don't bind, else we get
+ -- a substitution looking like x->x, and that sends
+ -- Unify.matchTy into a loop
+ = match (App e1 (mkVarArg new_id)) e2 tpl_vars kont subst
+ | otherwise
= bind [new_id] [x2] (match (App e1 (mkVarArg new_id)) e2) tpl_vars kont subst
where
new_id = uniqAway (substInScope subst) x2
-- The first \x is ok, but when we inline k, hoping it might
-- match (:) we find a second \x.
-match (Case e1 x1 alts1) (Case e2 x2 alts2) tpl_vars kont subst
- = match e1 e2 tpl_vars case_kont subst
+-- gaw 2004
+match_ (Case e1 x1 ty1 alts1) (Case e2 x2 ty2 alts2) tpl_vars kont subst
+ = (match_ty ty1 ty2 tpl_vars $
+ match e1 e2 tpl_vars case_kont) subst
where
case_kont subst = bind [x1] [x2] (match_alts alts1 (sortLe le_alt alts2))
tpl_vars kont subst
-match (Type ty1) (Type ty2) tpl_vars kont subst
+match_ (Type ty1) (Type ty2) tpl_vars kont subst
= match_ty ty1 ty2 tpl_vars kont subst
-match (Note (Coerce to1 from1) e1) (Note (Coerce to2 from2) e2)
+match_ (Note (Coerce to1 from1) e1) (Note (Coerce to2 from2) e2)
tpl_vars kont subst
= (match_ty to1 to2 tpl_vars $
match_ty from1 from2 tpl_vars $
-- variable, we expand it so long as its unfolding is a WHNF
-- (Its occurrence information is not necessarily up to date,
-- so we don't use it.)
-match e1 (Var v2) tpl_vars kont subst
+match_ e1 (Var v2) tpl_vars kont subst
| isCheapUnfolding unfolding
= match e1 (unfoldingTemplate unfolding) tpl_vars kont subst
where
-- We can't cope with lets in the template
-match e1 e2 tpl_vars kont subst = match_fail
+match_ e1 e2 tpl_vars kont subst = match_fail
------------------------------------------
subst' = bindSubstList subst vs1 vs2
-- The unBindSubst relies on no shadowing in the template
- not_in_subst v = isNothing (lookupSubst subst v)
+ not_in_subst v = isNothing (lookupVar subst v)
bug_msg = sep [ppr vs1, ppr vs2]
----------------------------------------
\begin{code}
----------------------------------------
match_ty ty1 ty2 tpl_vars kont subst
- = TcType.match ty1 ty2 tpl_vars kont' (substEnv subst)
- where
- kont' senv = kont (setSubstEnv subst senv)
+ = case Unify.matchTyX tpl_vars (getTvSubstEnv subst) ty1 ty2 of
+ Just tv_env' -> kont (setTvSubstEnv subst tv_env')
+ Nothing -> match_fail
\end{code}
ruleCheck env (Note n e) = ruleCheck env e
ruleCheck env (Let bd e) = ruleCheckBind env bd `unionBags` ruleCheck env e
ruleCheck env (Lam b e) = ruleCheck env e
-ruleCheck env (Case e _ as) = ruleCheck env e `unionBags`
- unionManyBags [ruleCheck env r | (_,_,r) <- as]
+-- gaw 2004
+ruleCheck env (Case e _ _ as) = ruleCheck env e `unionBags`
+ unionManyBags [ruleCheck env r | (_,_,r) <- as]
ruleCheckApp env (App f a) as = ruleCheck env a `unionBags` ruleCheckApp env f (a:as)
ruleCheckApp env (Var f) as = ruleCheckFun env f as
projects / ghc-hetmet.git / blobdiff