extendInScopeSet, extendInScopeSetList, modifyInScopeSet,
getInScopeVars, lookupInScope, elemInScopeSet, uniqAway,
+ -- RnEnv2 and its operations
+ RnEnv2, mkRnEnv2, rnBndr2, rnBndrs2, rnOccL, rnOccR, inRnEnvL, inRnEnvR,
+ rnBndrL, rnBndrR, nukeRnEnvL, nukeRnEnvR,
+
-- TidyEnvs
TidyEnv, emptyTidyEnv
) where
import VarSet
import UniqFM
import Unique ( Unique, deriveUnique, getUnique )
-import Util ( zipEqual )
+import Util ( zipEqual, foldl2 )
+import Maybes ( orElse, isJust )
import CmdLineOpts ( opt_PprStyle_Debug )
import Outputable
import FastTypes
-- in-scope set, and gives that to v. It starts with v's current unique, of course,
-- in the hope that it won't have to change it, and thereafter uses a combination
-- of that and the hash-code found in the in-scope set
-uniqAway (InScope set n) var
- | not (var `elemVarSet` set) = var -- Nothing to do
- | otherwise = try 1#
+uniqAway in_scope var
+ | var `elemInScopeSet` in_scope = uniqAway' in_scope var -- Make a new one
+ | otherwise = var -- Nothing to do
+
+uniqAway' :: InScopeSet -> Var -> Var
+-- This one *always* makes up a new variable
+uniqAway' (InScope set n) var
+ = try 1#
where
orig_unique = getUnique var
try k
%************************************************************************
%* *
+ Dual renaming
+%* *
+%************************************************************************
+
+When we are comparing (or matching) types or terms, we are faced with
+"going under" corresponding binders. E.g. when comparing
+ \x. e1 ~ \y. e2
+
+Basically we want to rename [x->y] or [y->x], but there are lots of
+things we must be careful of. In particular, x might be free in e2, or
+y in e1. So the idea is that we come up with a fresh binder that is free
+in neither, and rename x and y respectively. That means we must maintain
+ a) a renaming for the left-hand expression
+ b) a renaming for the right-hand expressions
+ c) an in-scope set
+
+Furthermore, when matching, we want to be able to have an 'occurs check',
+to prevent
+ \x. f ~ \y. y
+matching with f->y. So for each expression we want to know that set of
+locally-bound variables. That is precisely the domain of the mappings (a)
+and (b), but we must ensure that we always extend the mappings as we go in.
+
+
+\begin{code}
+data RnEnv2
+ = RV2 { envL :: VarEnv Var -- Renaming for Left term
+ , envR :: VarEnv Var -- Renaming for Right term
+ , in_scope :: InScopeSet } -- In scope in left or right terms
+
+-- The renamings envL and envR are *guaranteed* to contain a binding
+-- for every variable bound as we go into the term, even if it is not
+-- renamed. That way we can ask what variables are locally bound
+-- (inRnEnvL, inRnEnvR)
+
+mkRnEnv2 :: InScopeSet -> RnEnv2
+mkRnEnv2 vars = RV2 { envL = emptyVarEnv
+ , envR = emptyVarEnv
+ , in_scope = vars }
+
+rnBndrs2 :: RnEnv2 -> [Var] -> [Var] -> RnEnv2
+-- Arg lists must be of equal length
+rnBndrs2 env bsL bsR = foldl2 rnBndr2 env bsL bsR
+
+rnBndr2 :: RnEnv2 -> Var -> Var -> RnEnv2
+-- (rnBndr2 env bL bR) go under a binder bL in the Left term 1,
+-- and binder bR in the Right term
+-- It finds a new binder, new_b,
+-- and returns an environment mapping bL->new_b and bR->new_b resp.
+rnBndr2 (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bL bR
+ = RV2 { envL = extendVarEnv envL bL new_b -- See Note
+ , envR = extendVarEnv envR bR new_b -- [Rebinding]
+ , in_scope = extendInScopeSet in_scope new_b }
+ where
+ -- Find a new binder not in scope in either term
+ new_b | not (bL `elemInScopeSet` in_scope) = bL
+ | not (bR `elemInScopeSet` in_scope) = bR
+ | otherwise = uniqAway' in_scope bL
+
+ -- Note [Rebinding]
+ -- If the new var is the same as the old one, note that
+ -- the extendVarEnv *deletes* any current renaming
+ -- E.g. (\x. \x. ...) ~ (\y. \z. ...)
+ --
+ -- Inside \x \y { [x->y], [y->y], {y} }
+ -- \x \z { [x->x], [y->y, z->x], {y,x} }
+
+rnBndrL, rnBndrR :: RnEnv2 -> Var -> (RnEnv2, Var)
+-- Used when there's a binder on one side or the other only
+-- Useful when eta-expanding
+rnBndrL (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bL
+ = (RV2 { envL = extendVarEnv envL bL new_b
+ , envR = envR
+ , in_scope = extendInScopeSet in_scope new_b }, new_b)
+ where
+ new_b | not (bL `elemInScopeSet` in_scope) = bL
+ | otherwise = uniqAway' in_scope bL
+
+rnBndrR (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bR
+ = (RV2 { envL = envL
+ , envR = extendVarEnv envR bR new_b
+ , in_scope = extendInScopeSet in_scope new_b }, new_b)
+ where
+ new_b | not (bR `elemInScopeSet` in_scope) = bR
+ | otherwise = uniqAway' in_scope bR
+
+rnOccL, rnOccR :: RnEnv2 -> Var -> Var
+-- Look up the renaming of an occurrence in the left or right term
+rnOccL (RV2 { envL = env }) v = lookupVarEnv env v `orElse` v
+rnOccR (RV2 { envR = env }) v = lookupVarEnv env v `orElse` v
+
+inRnEnvL, inRnEnvR :: RnEnv2 -> Var -> Bool
+-- Tells whether a variable is locally bound
+inRnEnvL (RV2 { envL = env }) v = isJust (lookupVarEnv env v)
+inRnEnvR (RV2 { envR = env }) v = isJust (lookupVarEnv env v)
+
+nukeRnEnvL, nukeRnEnvR :: RnEnv2 -> RnEnv2
+nukeRnEnvL env = env { envL = emptyVarEnv }
+nukeRnEnvR env = env { envR = emptyVarEnv }
+\end{code}
+
+
+%************************************************************************
+%* *
Tidying
%* *
%************************************************************************
lookupVarEnv_Directly = lookupUFM_Directly
filterVarEnv_Directly = filterUFM_Directly
-zipVarEnv tyvars tys = mkVarEnv (zipEqual "zipVarEnv" tyvars tys)
-lookupVarEnv_NF env id = case (lookupVarEnv env id) of { Just xx -> xx }
+zipVarEnv tyvars tys = mkVarEnv (zipEqual "zipVarEnv" tyvars tys)
+lookupVarEnv_NF env id = case (lookupVarEnv env id) of { Just xx -> xx }
\end{code}
@modifyVarEnv@: Look up a thing in the VarEnv,
import ErrUtils ( dumpIfSet_core, ghcExit, Message, showPass,
mkLocMessage, debugTraceMsg )
import SrcLoc ( SrcLoc, noSrcLoc, mkSrcSpan )
-import Type ( Type, tyVarsOfType, eqType,
+import Type ( Type, tyVarsOfType, coreEqType,
splitFunTy_maybe, mkTyVarTys,
splitForAllTy_maybe, splitTyConApp_maybe,
isUnLiftedType, typeKind,
-- check ty2 is subtype of ty1 (ie, has same structure but usage
-- annotations need only be consistent, not equal)
-- Assumes ty1,ty2 are have alrady had the substitution applied
-checkTys ty1 ty2 msg = checkL (ty1 `eqType` ty2) msg
+checkTys ty1 ty2 msg = checkL (ty1 `coreEqType` ty2) msg
\end{code}
%************************************************************************
hashExpr,
-- Equality
- cheapEqExpr, eqExpr, applyTypeToArgs, applyTypeToArg
+ cheapEqExpr, tcEqExpr, tcEqExprX, applyTypeToArgs, applyTypeToArg
) where
#include "HsVersions.h"
import GLAEXTS -- For `xori`
import CoreSyn
+import CoreFVs ( exprFreeVars )
import PprCore ( pprCoreExpr )
import Var ( Var )
+import VarSet ( unionVarSet )
import VarEnv
import Name ( hashName )
import Packages ( isDllName )
import IdInfo ( GlobalIdDetails(..), megaSeqIdInfo )
import NewDemand ( appIsBottom )
import Type ( Type, mkFunTy, mkForAllTy, splitFunTy_maybe,
- splitFunTy,
+ splitFunTy, tcEqTypeX,
applyTys, isUnLiftedType, seqType, mkTyVarTy,
splitForAllTy_maybe, isForAllTy, splitRecNewType_maybe,
- splitTyConApp_maybe, eqType, funResultTy, applyTy
+ splitTyConApp_maybe, coreEqType, funResultTy, applyTy
)
import TyCon ( tyConArity )
-- gaw 2004
import Unique ( Unique )
import Outputable
import TysPrim ( alphaTy ) -- Debugging only
-import Util ( equalLength, lengthAtLeast )
+import Util ( equalLength, lengthAtLeast, foldl2 )
\end{code}
mkCoerce2 :: Type -> Type -> CoreExpr -> CoreExpr
mkCoerce2 to_ty from_ty (Note (Coerce to_ty2 from_ty2) expr)
- = ASSERT( from_ty `eqType` to_ty2 )
+ = ASSERT( from_ty `coreEqType` to_ty2 )
mkCoerce2 to_ty from_ty2 expr
mkCoerce2 to_ty from_ty expr
- | to_ty `eqType` from_ty = expr
- | otherwise = ASSERT( from_ty `eqType` exprType expr )
+ | to_ty `coreEqType` from_ty = expr
+ | otherwise = ASSERT( from_ty `coreEqType` exprType expr )
Note (Coerce to_ty from_ty) expr
\end{code}
cheapEqExpr (Var v1) (Var v2) = v1==v2
cheapEqExpr (Lit lit1) (Lit lit2) = lit1 == lit2
-cheapEqExpr (Type t1) (Type t2) = t1 `eqType` t2
+cheapEqExpr (Type t1) (Type t2) = t1 `coreEqType` t2
cheapEqExpr (App f1 a1) (App f2 a2)
= f1 `cheapEqExpr` f2 && a1 `cheapEqExpr` a2
\begin{code}
-eqExpr :: CoreExpr -> CoreExpr -> Bool
- -- Works ok at more general type, but only needed at CoreExpr
- -- Used in rule matching, so when we find a type we use
- -- eqTcType, which doesn't look through newtypes
- -- [And it doesn't risk falling into a black hole either.]
-eqExpr e1 e2
- = eq emptyVarEnv e1 e2
+tcEqExpr :: CoreExpr -> CoreExpr -> Bool
+-- Used in rule matching, so does *not* look through
+-- newtypes, predicate types; hence tcEqExpr
+
+tcEqExpr e1 e2 = tcEqExprX rn_env e1 e2
where
- -- The "env" maps variables in e1 to variables in ty2
- -- So when comparing lambdas etc,
- -- we in effect substitute v2 for v1 in e1 before continuing
- eq env (Var v1) (Var v2) = case lookupVarEnv env v1 of
- Just v1' -> v1' == v2
- Nothing -> v1 == v2
-
- eq env (Lit lit1) (Lit lit2) = lit1 == lit2
- eq env (App f1 a1) (App f2 a2) = eq env f1 f2 && eq env a1 a2
- eq env (Lam v1 e1) (Lam v2 e2) = eq (extendVarEnv env v1 v2) e1 e2
- eq env (Let (NonRec v1 r1) e1)
- (Let (NonRec v2 r2) e2) = eq env r1 r2 && eq (extendVarEnv env v1 v2) e1 e2
- eq env (Let (Rec ps1) e1)
- (Let (Rec ps2) e2) = equalLength ps1 ps2 &&
- and (zipWith eq_rhs ps1 ps2) &&
- eq env' e1 e2
+ rn_env = mkRnEnv2 (mkInScopeSet (exprFreeVars e1 `unionVarSet` exprFreeVars e2))
+
+tcEqExprX :: RnEnv2 -> CoreExpr -> CoreExpr -> Bool
+tcEqExprX env (Var v1) (Var v2) = rnOccL env v1 == rnOccR env v2
+tcEqExprX env (Lit lit1) (Lit lit2) = lit1 == lit2
+tcEqExprX env (App f1 a1) (App f2 a2) = tcEqExprX env f1 f2 && tcEqExprX env a1 a2
+tcEqExprX env (Lam v1 e1) (Lam v2 e2) = tcEqExprX (rnBndr2 env v1 v2) e1 e2
+tcEqExprX env (Let (NonRec v1 r1) e1)
+ (Let (NonRec v2 r2) e2) = tcEqExprX env r1 r2
+ && tcEqExprX (rnBndr2 env v1 v2) e1 e2
+tcEqExprX env (Let (Rec ps1) e1)
+ (Let (Rec ps2) e2) = equalLength ps1 ps2
+ && and (zipWith eq_rhs ps1 ps2)
+ && tcEqExprX env' e1 e2
where
- env' = extendVarEnvList env [(v1,v2) | ((v1,_),(v2,_)) <- zip ps1 ps2]
- eq_rhs (_,r1) (_,r2) = eq env' r1 r2
- eq env (Case e1 v1 t1 a1)
- (Case e2 v2 t2 a2) = eq env e1 e2 &&
- t1 `eqType` t2 &&
- equalLength a1 a2 &&
- and (zipWith (eq_alt env') a1 a2)
+ env' = foldl2 rn_bndr2 env ps2 ps2
+ rn_bndr2 env (b1,_) (b2,_) = rnBndr2 env b1 b2
+ eq_rhs (_,r1) (_,r2) = tcEqExprX env' r1 r2
+tcEqExprX env (Case e1 v1 t1 a1)
+ (Case e2 v2 t2 a2) = tcEqExprX env e1 e2
+ && tcEqTypeX env t1 t2
+ && equalLength a1 a2
+ && and (zipWith (eq_alt env') a1 a2)
where
- env' = extendVarEnv env v1 v2
+ env' = rnBndr2 env v1 v2
- eq env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && eq env e1 e2
- eq env (Type t1) (Type t2) = t1 `eqType` t2
- eq env e1 e2 = False
+tcEqExprX env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && tcEqExprX env e1 e2
+tcEqExprX env (Type t1) (Type t2) = tcEqTypeX env t1 t2
+tcEqExprX env e1 e2 = False
- eq_list env [] [] = True
- eq_list env (e1:es1) (e2:es2) = eq env e1 e2 && eq_list env es1 es2
- eq_list env es1 es2 = False
-
- eq_alt env (c1,vs1,r1) (c2,vs2,r2) = c1==c2 &&
- eq (extendVarEnvList env (vs1 `zip` vs2)) r1 r2
-
- eq_note env (SCC cc1) (SCC cc2) = cc1 == cc2
- eq_note env (Coerce t1 f1) (Coerce t2 f2) = t1 `eqType` t2 && f1 `eqType` f2
- eq_note env InlineCall InlineCall = True
- eq_note env (CoreNote s1) (CoreNote s2) = s1 == s2
- eq_note env other1 other2 = False
+eq_alt env (c1,vs1,r1) (c2,vs2,r2) = c1==c2 && tcEqExprX (rnBndrs2 env vs1 vs2) r1 r2
+
+eq_note env (SCC cc1) (SCC cc2) = cc1 == cc2
+eq_note env (Coerce t1 f1) (Coerce t2 f2) = tcEqTypeX env t1 t2 && tcEqTypeX env f1 f2
+eq_note env InlineCall InlineCall = True
+eq_note env (CoreNote s1) (CoreNote s2) = s1 == s2
+eq_note env other1 other2 = False
\end{code}
\begin{code}
module Subst (
-- Substitution stuff
- Subst, SubstResult(..),
- emptySubst, mkSubst, substInScope, substTy,
+ IdSubstEnv, SubstResult(..),
+
+ Subst, emptySubst, mkSubst, substInScope, substTy,
lookupIdSubst, lookupTvSubst, isEmptySubst,
extendIdSubst, extendIdSubstList, extendTvSubst, extendTvSubstList,
zapSubstEnv, setSubstEnv,
import Module ( moduleString )
import Name ( getOccString, NamedThing(..) )
import OccName ( encodeFS )
-import Type ( repType, eqType, typePrimRep )
+import Type ( repType, coreEqType, typePrimRep )
import TcType ( Type, mkFunTys, mkForAllTys, mkTyConApp,
mkFunTy, tcSplitTyConApp_maybe,
tcSplitForAllTys, tcSplitFunTys, tcTyConAppArgs,
-> DsM ([Binding], SDoc, SDoc)
dsCImport id (CLabel cid) _ _ no_hdrs
= resultWrapper (idType id) `thenDs` \ (resTy, foRhs) ->
- ASSERT(fromJust resTy `eqType` addrPrimTy) -- typechecker ensures this
+ ASSERT(fromJust resTy `coreEqType` addrPrimTy) -- typechecker ensures this
let rhs = foRhs (mkLit (MachLabel cid Nothing)) in
returnDs ([(setImpInline no_hdrs id, rhs)], empty, empty)
dsCImport id (CFunction target) cconv safety no_hdrs
= map snd extra_cnames_and_tys ++ arg_htys
-- stuff to do with the return type of the C function
- res_hty_is_unit = res_hty `eqType` unitTy -- Look through any newtypes
+ res_hty_is_unit = res_hty `coreEqType` unitTy -- Look through any newtypes
cResType | res_hty_is_unit = text "void"
| otherwise = showStgType res_hty
import TyCon ( tyConDataCons_maybe, isEnumerationTyCon, isNewTyCon )
import DataCon ( dataConTag, dataConTyCon, dataConWorkId, fIRST_TAG )
import CoreUtils ( cheapEqExpr, exprIsConApp_maybe )
-import Type ( tyConAppTyCon, eqType )
+import Type ( tyConAppTyCon, coreEqType )
import OccName ( occNameUserString)
import PrelNames ( unpackCStringFoldrName, unpackCStringFoldrIdKey, hasKey,
eqStringName, unpackCStringIdKey )
]
| unpk `hasKey` unpackCStringFoldrIdKey &&
c1 `cheapEqExpr` c2
- = ASSERT( ty1 `eqType` ty2 )
+ = ASSERT( ty1 `coreEqType` ty2 )
Just (Var unpk `App` Type ty1
`App` Lit (MachStr (s1 `appendFS` s2))
`App` c1
import BasicTypes ( isMarkedStrict )
import CostCentre ( currentCCS )
import Type ( TvSubstEnv, isUnLiftedType, seqType, tyConAppArgs, funArgTy,
- splitFunTy_maybe, splitFunTy, eqType, substTy,
+ splitFunTy_maybe, splitFunTy, coreEqType, substTy,
mkTyVarTys, mkTyConApp
)
import VarEnv ( elemVarEnv )
-- we may find (coerce T (coerce S (\x.e))) y
-- and we'd like it to simplify to e[y/x] in one round
-- of simplification
- | t1 `eqType` k1 = cont -- The coerces cancel out
+ | t1 `coreEqType` k1 = cont -- The coerces cancel out
| otherwise = CoerceIt t1 cont -- They don't cancel, but
-- the inner one is redundant
import CoreSyn -- All of it
import OccurAnal ( occurAnalyseRule )
-import CoreFVs ( exprFreeVars, ruleRhsFreeVars )
+import CoreFVs ( exprFreeVars, exprsFreeVars, ruleRhsFreeVars )
import CoreUnfold ( isCheapUnfolding, unfoldingTemplate )
-import CoreUtils ( eqExpr )
+import CoreUtils ( tcEqExprX )
import CoreTidy ( pprTidyIdRules )
-import Subst ( Subst, SubstResult(..), extendIdSubst,
- getTvSubstEnv, setTvSubstEnv,
- emptySubst, isInScope, lookupIdSubst, lookupTvSubst,
- bindSubstList, unBindSubstList, substInScope
- )
+import Subst ( IdSubstEnv, SubstResult(..) )
import Id ( Id, idUnfolding, idSpecialisation, setIdSpecialisation )
-import Var ( Var, isId )
+import Var ( Var )
import VarSet
import VarEnv
-import TcType ( mkTyVarTy )
-import qualified Unify ( matchTyX )
+import TcType ( TvSubstEnv )
+import Unify ( matchTyX, MatchEnv(..) )
import BasicTypes ( Activation, CompilerPhase, isActive )
import Outputable
import FastString
-import Maybe ( isJust, isNothing, fromMaybe )
+import Maybe ( isJust, fromMaybe )
import Util ( sortLe )
import Bag
import List ( isPrefixOf )
--
-- Any 'surplus' arguments in the input are simply put on the end
-- of the output.
---
--- ASSUMPTION (A):
--- A1. No top-level variable is bound in the target
--- A2. No template variable is bound in the target
--- A3. No lambda bound template variable is free in any subexpression of the target
---
--- To see why A1 is necessary, consider matching
--- \x->f against \f->f
--- When we meet the lambdas we substitute [f/x] in the template (a no-op),
--- and then erroneously succeed in matching f against f.
---
--- To see why A2 is needed consider matching
--- forall a. \b->b against \a->3
--- When we meet the lambdas we substitute [a/b] in the template, and then
--- erroneously succeed in matching what looks like the template variable 'a' against 3.
---
--- A3 is needed to validate the rule that says
--- (\x->E) matches F
--- if
--- (\x->E) matches (\x->F x)
-
matchRule is_active in_scope rule@(BuiltinRule name match_fn) args
= case match_fn args of
| not (is_active act)
= Nothing
| otherwise
- = go tpl_args args emptySubst
- -- We used to use the in_scope set, but I don't think that's necessary
- -- After all, the result is going to be simplified again with that in_scope set
- where
- tpl_var_set = mkVarSet tpl_vars
-
- -----------------------
- -- Do the business
- go (tpl_arg:tpl_args) (arg:args) subst = match tpl_arg arg tpl_var_set (go tpl_args args) subst
-
- -- Two easy ways to terminate
- go [] [] subst = Just (rn, app_match subst (mkLams tpl_vars rhs) tpl_vars)
- go [] args subst = Just (rn, app_match subst (mkLams tpl_vars rhs) tpl_vars `mkApps` args)
-
- -- One tiresome way to terminate: check for excess unmatched
- -- template arguments
- go tpl_args [] subst = Nothing -- Failure
-
-
- -----------------------
- app_match subst fn vs = foldl go fn vs
- 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
- template args than real args.
-
- I now think this is probably a bad idea.
- Should the template (map f xs) match (map g)? I think not.
- For a start, in general eta expansion wastes work.
- SLPJ July 99
-
- = case eta_complete tpl_args (mkVarSet leftovers) of
- Just leftovers' -> Just (rn, mkLams done (mkLams leftovers' rhs),
- mk_result_args subst done)
- Nothing -> Nothing -- Failure
- where
- (done, leftovers) = partition (\v -> isJust (lookupSubstEnv subst_env v))
- (map zapOccInfo tpl_vars)
- -- Zap the occ info
- subst_env = substEnv subst
-
- -----------------------
- eta_complete [] vars = ASSERT( isEmptyVarSet vars )
- Just []
- eta_complete (Type ty:tpl_args) vars
- = case getTyVar_maybe ty of
- Just tv | tv `elemVarSet` vars
- -> case eta_complete tpl_args (vars `delVarSet` tv) of
- Just vars' -> Just (tv:vars')
- Nothing -> Nothing
- other -> Nothing
-
- eta_complete (Var v:tpl_args) vars
- | v `elemVarSet` vars
- = case eta_complete tpl_args (vars `delVarSet` v) of
- Just vars' -> Just (v:vars')
- Nothing -> Nothing
-
- eta_complete other vars = Nothing
-
-
-zapOccInfo bndr | isTyVar bndr = bndr
- | otherwise = zapLamIdInfo bndr
--}
+ = case matchN in_scope tpl_vars tpl_args args of
+ Just (tpl_vals, leftovers) -> Just (rn, mkLams tpl_vars rhs `mkApps` tpl_vals `mkApps` leftovers)
+ Nothing -> Nothing
\end{code}
\begin{code}
-type Matcher result = VarSet -- Template variables
- -> (Subst -> Maybe result) -- Continuation if success
- -> Subst -> Maybe result -- Substitution so far -> result
--- The *SubstEnv* in these Substs apply to the TEMPLATE only
-
--- 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
+matchN :: InScopeSet
+ -> [Var] -- Template tyvars
+ -> [CoreExpr] -- Template
+ -> [CoreExpr] -- Target; can have more elts than template
+ -> Maybe ([CoreExpr], -- What is substituted for each template var
+ [CoreExpr]) -- Leftover target exprs
+
+matchN in_scope tmpl_vars tmpl_es target_es
+ = do { (subst, leftover_es) <- go init_menv emptySubstEnv tmpl_es target_es
+ ; return (map (lookup_tmpl subst) tmpl_vars, leftover_es) }
+ where
+ init_menv = ME { me_tmpls = mkVarSet tmpl_vars, me_env = init_rn_env }
+ init_rn_env = mkRnEnv2 (extendInScopeSetList in_scope tmpl_vars)
+
+ go menv subst [] es = Just (subst, es)
+ go menv subst ts [] = Nothing -- Fail if too few actual args
+ go menv subst (t:ts) (e:es) = do { subst1 <- match menv subst t e
+ ; go menv subst1 ts es }
+
+ lookup_tmpl :: (TvSubstEnv, IdSubstEnv) -> Var -> CoreExpr
+ lookup_tmpl (tv_subst, id_subst) tmpl_var
+ | isTyVar tmpl_var = case lookupVarEnv tv_subst tmpl_var of
+ Just ty -> Type ty
+ Nothing -> unbound tmpl_var
+ | otherwise = case lookupVarEnv id_subst tmpl_var of
+ Just (DoneEx e) -> e
+ other -> unbound tmpl_var
+
+ unbound var = pprPanic "Template variable unbound in rewrite rule" (ppr var)
+
+emptySubstEnv :: (TvSubstEnv, IdSubstEnv)
+emptySubstEnv = (emptyVarEnv, emptyVarEnv)
+
+
+-- At one stage I tried to match even if there are more
+-- template args than real args.
+
+-- I now think this is probably a bad idea.
+-- Should the template (map f xs) match (map g)? I think not.
+-- For a start, in general eta expansion wastes work.
+-- SLPJ July 99
+
+
+match :: MatchEnv
+ -> (TvSubstEnv, IdSubstEnv)
+ -> CoreExpr -- Template
-> CoreExpr -- Target
- -> Matcher result
-
-match_fail = Nothing
-
--- 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 (extendIdSubst subst v1 (DoneEx e2))
+ -> Maybe (TvSubstEnv, IdSubstEnv)
+-- See the notes with Unify.match, which matches types
+-- Everything is very similar for terms
- | eqExpr (Var v1) e2 -> kont subst
- -- v1 is not a template variable, so it must be a global constant
-
- Just (DoneEx e2') | eqExpr e2' e2 -> kont subst
+-- Interesting examples:
+-- Consider matching
+-- \x->f against \f->f
+-- When we meet the lambdas we must remember to rename f to f' in the
+-- second expresion. The RnEnv2 does that.
+--
+-- Consider matching
+-- forall a. \b->b against \a->3
+-- We must rename the \a. Otherwise when we meet the lambdas we
+-- might substitute [a/b] in the template, and then erroneously
+-- succeed in matching what looks like the template variable 'a' against 3.
+
+-- The Var case follows closely what happens in Unify.match
+match menv subst@(tv_subst, id_subst) (Var v1) e2
+ | v1 `elemVarSet` me_tmpls menv
+ = case lookupVarEnv id_subst v1' of
+ Nothing | any (inRnEnvR rn_env) (varSetElems (exprFreeVars e2))
+ -> Nothing -- Occurs check failure
+ -- e.g. match forall a. (\x-> a x) against (\y. y y)
+
+ | otherwise
+ -> Just (tv_subst, extendVarEnv id_subst v1 (DoneEx e2))
+
+ Just (DoneEx e2') | tcEqExprX (nukeRnEnvL rn_env) e2' e2
+ -> Just subst
+
+ other -> Nothing
+
+ | otherwise -- v1 is not a template variable
+ = case e2 of
+ Var v2 | v1' == rnOccR rn_env v2 -> Just subst
+ other -> Nothing
+ where
+ rn_env = me_env menv
+ v1' = rnOccL rn_env v1
- other -> match_fail
+-- Here is another important rule: if the term being matched is a
+-- 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 menv subst e1 (Var v2)
+ | isCheapUnfolding unfolding
+ = match menv subst e1 (unfoldingTemplate unfolding)
+ where
+ unfolding = idUnfolding v2
-match_ (Lit lit1) (Lit lit2) tpl_vars kont subst
+match menv subst (Lit lit1) (Lit lit2)
| lit1 == lit2
- = kont subst
+ = Just 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 menv subst (App f1 a1) (App f2 a2)
+ = do { subst' <- match menv subst f1 f2
+ ; match menv subst' a1 a2 }
-match_ (Lam x1 e1) (Lam x2 e2) tpl_vars kont subst
- = bind [x1] [x2] (match e1 e2) tpl_vars kont subst
+match menv subst (Lam x1 e1) (Lam x2 e2)
+ = match menv' subst e1 e2
+ where
+ menv' = menv { me_env = rnBndr2 (me_env menv) x1 x2 }
-- This rule does eta expansion
-- (\x.M) ~ N iff M ~ N x
--- See assumption A3
-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
- | 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
+match menv subst (Lam x1 e1) e2
+ = match menv' subst e1 (App e2 (varToCoreExpr new_x))
where
- new_id = uniqAway (substInScope subst) x2
- -- This uniqAway is actually needed. Here's the example:
- -- rule: foldr (mapFB (:) f) [] = mapList
- -- target: foldr (\x. mapFB k f x) []
- -- where
- -- k = \x. mapFB ... x
- -- The first \x is ok, but when we inline k, hoping it might
- -- match (:) we find a second \x.
+ (rn_env', new_x) = rnBndrL (me_env menv) x1
+ menv' = menv { me_env = rn_env' }
--- 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
+-- Eta expansion the other way
+-- M ~ (\y.N) iff M y ~ N
+match menv subst e1 (Lam x2 e2)
+ = match menv' subst (App e1 (varToCoreExpr new_x)) e2
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_ty ty1 ty2 tpl_vars kont subst
+ (rn_env', new_x) = rnBndrR (me_env menv) x2
+ menv' = menv { me_env = rn_env' }
-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 $
- match e1 e2 tpl_vars kont) subst
+match menv subst (Case e1 x1 ty1 alts1) (Case e2 x2 ty2 alts2)
+ = do { subst1 <- match_ty menv subst ty1 ty2
+ ; subst2 <- match menv subst1 e1 e2
+ ; let menv' = menv { me_env = rnBndr2 (me_env menv) x2 x2 }
+ ; match_alts menv' subst2 (sortLe le_alt alts1) (sortLe le_alt alts2)
+ }
+match menv subst (Type ty1) (Type ty2)
+ = match_ty menv subst ty1 ty2
-{- I don't buy this let-rule any more
- The let rule fails on matching
- forall f,x,xs. f (x:xs)
- against
- f (let y = e in (y:[]))
- because we just get x->y, which is bogus.
+match menv subst (Note (Coerce to1 from1) e1) (Note (Coerce to2 from2) e2)
+ = do { subst1 <- match_ty menv subst to1 to2
+ ; subst2 <- match_ty menv subst1 from1 from2
+ ; match menv subst2 e1 e2 }
-- This is an interesting rule: we simply ignore lets in the
-- term being matched against! The unfolding inside it is (by assumption)
-- already inside any occurrences of the bound variables, so we'll expand
--- them when we encounter them. Meanwhile, we can't get false matches because
--- (also by assumption) the term being matched has no shadowing.
-match e1 (Let bind e2) tpl_vars kont subst
- = match e1 e2 tpl_vars kont subst
--}
-
--- Here is another important rule: if the term being matched is a
--- 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
- | isCheapUnfolding unfolding
- = match e1 (unfoldingTemplate unfolding) tpl_vars kont subst
+-- them when we encounter them.
+match menv subst e1 (Let (NonRec x2 r2) e2)
+ = match menv' subst e1 e2
where
- unfolding = idUnfolding v2
-
-
--- We can't cope with lets in the template
-
-match_ e1 e2 tpl_vars kont subst = match_fail
-
+ menv' = menv { me_env = fst (rnBndrR (me_env menv) x2) }
+ -- It's important to do this renaming. For example:
+ -- Matching
+ -- forall f,x,xs. f (x:xs)
+ -- against
+ -- f (let y = e in (y:[]))
+ -- We must not get success with x->y! Instead, we
+ -- need an occurs check.
+
+-- Everything else fails
+match menv subst e1 e2 = Nothing
------------------------------------------
-match_alts [] [] tpl_vars kont subst
- = kont subst
-match_alts ((c1,vs1,r1):alts1) ((c2,vs2,r2):alts2) tpl_vars kont subst
+match_alts :: MatchEnv
+ -> (TvSubstEnv, IdSubstEnv)
+ -> [CoreAlt] -- Template
+ -> [CoreAlt] -- Target
+ -> Maybe (TvSubstEnv, IdSubstEnv)
+match_alts menv subst [] []
+ = return subst
+match_alts menv subst ((c1,vs1,r1):alts1) ((c2,vs2,r2):alts2)
| c1 == c2
- = bind vs1 vs2 (match r1 r2) tpl_vars
- (match_alts alts1 alts2 tpl_vars kont)
- subst
-match_alts alts1 alts2 tpl_vars kont subst = match_fail
-
-le_alt (con1, _, _) (con2, _, _) = con1 <= con2
-
-----------------------------------------
-bind :: [CoreBndr] -- Template binders
- -> [CoreBndr] -- Target binders
- -> Matcher result
- -> Matcher result
--- This makes uses of assumption (A) above. For example,
--- this would fail:
--- Template: (\x.y) (y is free)
--- Target : (\y.y) (y is bound)
--- We rename x to y in the template... but then erroneously
--- match y against y. But this can't happen because of (A)
-bind vs1 vs2 matcher tpl_vars kont subst
- = WARN( not (all not_in_subst vs1), bug_msg )
- matcher tpl_vars kont' subst'
+ = do { subst1 <- match menv' subst r1 r2
+ ; match_alts menv subst1 alts1 alts2 }
where
- kont' subst'' = kont (unBindSubstList subst'' vs1 vs2)
- subst' = bindSubstList subst vs1 vs2
+ menv' :: MatchEnv
+ menv' = menv { me_env = rnBndrs2 (me_env menv) vs1 vs2 }
- -- The unBindSubst relies on no shadowing in the template
- not_in_subst v = isNothing (lookupVar subst v)
- bug_msg = sep [ppr vs1, ppr vs2]
+match_alts menv subst alts1 alts2
+ = Nothing
-----------------------------------------
-mkVarArg :: CoreBndr -> CoreArg
-mkVarArg v | isId v = Var v
- | otherwise = Type (mkTyVarTy v)
+le_alt (con1, _, _) (con2, _, _) = con1 <= con2
\end{code}
Matching Core types: use the matcher in TcType.
We only want to replace (f T) with f', not (f Int).
\begin{code}
-----------------------------------------
-match_ty ty1 ty2 tpl_vars kont subst
- = case Unify.matchTyX tpl_vars (getTvSubstEnv subst) ty1 ty2 of
- Just tv_env' -> kont (setTvSubstEnv subst tv_env')
- Nothing -> match_fail
+------------------------------------------
+match_ty menv (tv_subst, id_subst) ty1 ty2
+ = do { tv_subst' <- Unify.matchTyX menv tv_subst ty1 ty2
+ ; return (tv_subst', id_subst) }
\end{code}
-
%************************************************************************
%* *
\subsection{Adding a new rule}
| not (isActive phase act) = text "active only in later phase"
| n_args < n_rule_args = text "too few arguments"
| n_mismatches == n_rule_args = text "no arguments match"
- | n_mismatches == 0 = text "all arguments match (considered individually), but the rule as a whole does not"
+ | n_mismatches == 0 = text "all arguments match (considered individually), but rule as a whole does not"
| otherwise = text "arguments" <+> ppr mismatches <+> text "do not match (1-indexing)"
where
n_rule_args = length rule_args
mismatches = [i | (rule_arg, (arg,i)) <- rule_args `zip` i_args,
not (isJust (match_fn rule_arg arg))]
- bndr_set = mkVarSet rule_bndrs
- match_fn rule_arg arg = match rule_arg arg bndr_set (\s -> Just ()) emptySubst
+ lhs_fvs = exprsFreeVars rule_args -- Includes template tyvars
+ match_fn rule_arg arg = match menv emptySubstEnv rule_arg arg
+ where
+ in_scope = lhs_fvs `unionVarSet` exprFreeVars arg
+ menv = ME { me_env = mkRnEnv2 (mkInScopeSet in_scope)
+ , me_tmpls = mkVarSet rule_bndrs }
\end{code}
import CoreSyn
import CoreLint ( showPass, endPass )
-import CoreUtils ( exprType, eqExpr, mkPiTypes )
+import CoreUtils ( exprType, tcEqExpr, mkPiTypes )
import CoreFVs ( exprsFreeVars )
import CoreTidy ( pprTidyIdRules )
import WwLib ( mkWorkerArgs )
(nubBy same_call good_calls `zip` [1..])
where
n_bndrs = length bndrs
- same_call as1 as2 = and (zipWith eqExpr as1 as2)
+ same_call as1 as2 = and (zipWith tcEqExpr as1 as2)
---------------------
good_arg :: ConstrEnv -> IdEnv ArgOcc -> (CoreBndr, CoreArg) -> Bool
import TysPrim ( realWorldStatePrimTy )
import UniqFM ( plusUFM_C, addToUFM_Directly, lookupUFM_Directly,
keysUFM, minusUFM, ufmToList, filterUFM )
-import Type ( isUnLiftedType, eqType )
+import Type ( isUnLiftedType, coreEqType )
import CoreLint ( showPass, endPass )
import Util ( mapAndUnzip, mapAccumL, mapAccumR, lengthIs )
import BasicTypes ( Arity, TopLevelFlag(..), isTopLevel, isNeverActive,
-- ; print len }
io_hack_reqd = con == DataAlt unboxedPairDataCon &&
- idType (head bndrs) `eqType` realWorldStatePrimTy
+ idType (head bndrs) `coreEqType` realWorldStatePrimTy
in
(final_alt_ty, (con, bndrs', rhs'))
\end{code}
import SrcLoc ( Located(..), unLoc, noLoc, getLoc )
import Bag
import Util ( isIn )
+import Maybes ( orElse )
import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec,
isNotTopLevel, isAlwaysActive )
import FiniteMap ( listToFM, lookupFM )
-- Try to match the context of this signature with
-- that of the first signature
- ; case tcMatchPreds tvs (sig_theta sig1) theta of {
+ ; case tcMatchPreds tvs theta (sig_theta sig1) of {
Nothing -> bale_out
; Just tenv -> do
; case check_tvs tenv tvs of
check_tvs :: TvSubstEnv -> [TcTyVar] -> Maybe [TcTyVar]
check_tvs tenv [] = Just []
check_tvs tenv (tv:tvs)
- | Just ty <- lookupVarEnv tenv tv
- = do { tv' <- tcGetTyVar_maybe ty
+ = do { let ty = lookupVarEnv tenv tv `orElse` mkTyVarTy tv
+ ; tv' <- tcGetTyVar_maybe ty
; tvs' <- check_tvs tenv tvs
; if tv' `elem` tvs'
then Nothing
else Just (tv':tvs') }
- | otherwise
- = do { tvs' <- check_tvs tenv tvs
- ; Just (tv:tvs') }
\end{code}
\begin{code}
= vcat [ addInstLoc [dict] ((ptext SLIT("Overlapping instances for")
<+> pprPred (dictPred dict))),
sep [ptext SLIT("Matching instances") <> colon,
- nest 2 (pprDFuns (dfuns ++ unifiers))],
+ nest 2 (vcat [pprDFuns dfuns, text "---", pprDFuns unifiers])],
ASSERT( not (null matches) )
if not (isSingleton matches)
then -- Two or more matches
---------------------------------
-- Predicates.
-- Again, newtypes are opaque
- tcEqType, tcEqTypes, tcEqPred, tcCmpType, tcCmpTypes, tcCmpPred,
+ tcEqType, tcEqTypes, tcEqPred, tcCmpType, tcCmpTypes, tcCmpPred, tcEqTypeX,
isSigmaTy, isOverloadedTy,
isDoubleTy, isFloatTy, isIntTy,
isIntegerTy, isAddrTy, isBoolTy, isUnitTy,
tidyTyVarBndr, tidyOpenTyVar,
tidyOpenTyVars,
isSubKind,
+
+ tcEqType, tcEqTypes, tcCmpType, tcCmpTypes,
+ tcEqPred, tcCmpPred, tcEqTypeX,
+
TvSubst(..),
TvSubstEnv, emptyTvSubst,
mkTvSubst, zipTvSubst, zipTopTvSubst, mkTopTvSubst,
import Class ( Class )
import Var ( TyVar, Id, isTcTyVar, tcTyVarDetails )
import ForeignCall ( Safety, playSafe, DNType(..) )
-import VarEnv
import VarSet
-- others:
import TysWiredIn ( unitTyCon, charTyCon, listTyCon )
import BasicTypes ( IPName(..), ipNameName )
import SrcLoc ( SrcLoc, SrcSpan )
-import Util ( cmpList, thenCmp, snocView )
+import Util ( snocView )
import Maybes ( maybeToBool, expectJust )
import Outputable
import DATA_IOREF
%************************************************************************
%* *
-\subsection{Comparison}
-%* *
-%************************************************************************
-
-Comparison, taking note of newtypes, predicates, etc,
-
-\begin{code}
-tcEqType :: Type -> Type -> Bool
-tcEqType ty1 ty2 = case ty1 `tcCmpType` ty2 of { EQ -> True; other -> False }
-
-tcEqTypes :: [Type] -> [Type] -> Bool
-tcEqTypes ty1 ty2 = case ty1 `tcCmpTypes` ty2 of { EQ -> True; other -> False }
-
-tcEqPred :: PredType -> PredType -> Bool
-tcEqPred p1 p2 = case p1 `tcCmpPred` p2 of { EQ -> True; other -> False }
-
--------------
-tcCmpType :: Type -> Type -> Ordering
-tcCmpType ty1 ty2 = cmpTy emptyVarEnv ty1 ty2
-
-tcCmpTypes tys1 tys2 = cmpTys emptyVarEnv tys1 tys2
-
-tcCmpPred p1 p2 = cmpPredTy emptyVarEnv p1 p2
--------------
-cmpTys env tys1 tys2 = cmpList (cmpTy env) tys1 tys2
-
--------------
-cmpTy :: TyVarEnv TyVar -> Type -> Type -> Ordering
- -- The "env" maps type variables in ty1 to type variables in ty2
- -- So when comparing for-alls.. (forall tv1 . t1) (forall tv2 . t2)
- -- we in effect substitute tv2 for tv1 in t1 before continuing
-
- -- Look through NoteTy
-cmpTy env (NoteTy _ ty1) ty2 = cmpTy env ty1 ty2
-cmpTy env ty1 (NoteTy _ ty2) = cmpTy env ty1 ty2
-
- -- Deal with equal constructors
-cmpTy env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of
- Just tv1a -> tv1a `compare` tv2
- Nothing -> tv1 `compare` tv2
-
-cmpTy env (PredTy p1) (PredTy p2) = cmpPredTy env p1 p2
-cmpTy env (AppTy f1 a1) (AppTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2
-cmpTy env (FunTy f1 a1) (FunTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2
-cmpTy env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmpTys env tys1 tys2)
-cmpTy env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTy (extendVarEnv env tv1 tv2) t1 t2
-
- -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy < PredTy
-cmpTy env (AppTy _ _) (TyVarTy _) = GT
-
-cmpTy env (FunTy _ _) (TyVarTy _) = GT
-cmpTy env (FunTy _ _) (AppTy _ _) = GT
-
-cmpTy env (TyConApp _ _) (TyVarTy _) = GT
-cmpTy env (TyConApp _ _) (AppTy _ _) = GT
-cmpTy env (TyConApp _ _) (FunTy _ _) = GT
-
-cmpTy env (ForAllTy _ _) (TyVarTy _) = GT
-cmpTy env (ForAllTy _ _) (AppTy _ _) = GT
-cmpTy env (ForAllTy _ _) (FunTy _ _) = GT
-cmpTy env (ForAllTy _ _) (TyConApp _ _) = GT
-
-cmpTy env (PredTy _) t2 = GT
-
-cmpTy env _ _ = LT
-\end{code}
-
-\begin{code}
-cmpPredTy :: TyVarEnv TyVar -> PredType -> PredType -> Ordering
-cmpPredTy env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` (cmpTy env ty1 ty2)
- -- Compare types as well as names for implicit parameters
- -- This comparison is used exclusively (I think) for the
- -- finite map built in TcSimplify
-cmpPredTy env (IParam _ _) (ClassP _ _) = LT
-cmpPredTy env (ClassP _ _) (IParam _ _) = GT
-cmpPredTy env (ClassP c1 tys1) (ClassP c2 tys2) = (c1 `compare` c2) `thenCmp` (cmpTys env tys1 tys2)
-\end{code}
-
-PredTypes are used as a FM key in TcSimplify,
-so we take the easy path and make them an instance of Ord
-
-\begin{code}
-instance Eq PredType where { (==) = tcEqPred }
-instance Ord PredType where { compare = tcCmpPred }
-\end{code}
-
-
-%************************************************************************
-%* *
\subsection{Predicates}
%* *
%************************************************************************
mkSynTy,
- repType, typePrimRep, coreView,
+ repType, typePrimRep, coreView, deepCoreView,
mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys,
applyTy, applyTys, isForAllTy, dropForAlls,
tidyTopType, tidyPred,
-- Comparison
- eqType,
+ coreEqType, tcEqType, tcEqTypes, tcCmpType, tcCmpTypes,
+ tcEqPred, tcCmpPred, tcEqTypeX,
-- Seq
seqType, seqTypes,
import CmdLineOpts ( opt_DictsStrict )
import SrcLoc ( noSrcLoc )
import Unique ( Uniquable(..) )
-import Util ( mapAccumL, seqList, lengthIs, snocView )
+import Util ( mapAccumL, seqList, lengthIs, snocView, thenCmp, isEqual )
import Outputable
import UniqSet ( sizeUniqSet ) -- Should come via VarSet
import Maybe ( isJust )
coreView (TyConApp tc tys) = expandNewTcApp tc tys
coreView ty = Nothing
+deepCoreView :: Type -> Type
+-- Apply coreView recursively
+deepCoreView ty
+ | Just ty' <- coreView ty = deepCoreView ty'
+deepCoreView (TyVarTy tv) = TyVarTy tv
+deepCoreView (TyConApp tc tys) = TyConApp tc (map deepCoreView tys)
+deepCoreView (AppTy t1 t2) = AppTy (deepCoreView t1) (deepCoreView t2)
+deepCoreView (FunTy t1 t2) = FunTy (deepCoreView t1) (deepCoreView t2)
+deepCoreView (ForAllTy tv ty) = ForAllTy tv (deepCoreView ty)
+ -- No NoteTy, no PredTy
+
expandNewTcApp :: TyCon -> [Type] -> Maybe Type
-- A local helper function (not exported)
-- Expands *the outermoset level of* a newtype application to
%************************************************************************
%* *
-\subsection{Equality on types}
+ Comparison of types
+ (We don't use instances so that we know where it happens)
%* *
%************************************************************************
-Comparison; don't use instances so that we know where it happens.
-Look through newtypes but not usage types.
+Two flavours:
+
+* tcEqType, tcCmpType do *not* look through newtypes, PredTypes
+* coreEqType *does* look through them
Note that eqType can respond 'False' for partial applications of newtypes.
Consider
newtype Parser m a = MkParser (Foogle m a)
-
Does
Monad (Parser m) `eqType` Monad (Foogle m)
-
Well, yes, but eqType won't see that they are the same.
I don't think this is harmful, but it's soemthing to watch out for.
+First, the external interface
+
+\begin{code}
+coreEqType :: Type -> Type -> Bool
+coreEqType t1 t2 = isEqual $ cmpType (deepCoreView t1) (deepCoreView t2)
+
+tcEqType :: Type -> Type -> Bool
+tcEqType t1 t2 = isEqual $ cmpType t1 t2
+
+tcEqTypes :: [Type] -> [Type] -> Bool
+tcEqTypes tys1 tys2 = isEqual $ cmpTypes tys1 tys2
+
+tcCmpType :: Type -> Type -> Ordering
+tcCmpType t1 t2 = cmpType t1 t2
+
+tcCmpTypes :: [Type] -> [Type] -> Ordering
+tcCmpTypes tys1 tys2 = cmpTypes tys1 tys2
+
+tcEqPred :: PredType -> PredType -> Bool
+tcEqPred p1 p2 = isEqual $ cmpPred p1 p2
+
+tcCmpPred :: PredType -> PredType -> Ordering
+tcCmpPred p1 p2 = cmpPred p1 p2
+
+tcEqTypeX :: RnEnv2 -> Type -> Type -> Bool
+tcEqTypeX env t1 t2 = isEqual $ cmpTypeX env t1 t2
+\end{code}
+
+Now here comes the real worker
+
\begin{code}
-eqType t1 t2 = eq_ty emptyVarEnv t1 t2
+cmpType :: Type -> Type -> Ordering
+cmpType t1 t2 = cmpTypeX rn_env t1 t2
+ where
+ rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfType t1 `unionVarSet` tyVarsOfType t2))
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes ts1 ts2 = cmpTypesX rn_env ts1 ts2
+ where
+ rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfTypes ts1 `unionVarSet` tyVarsOfTypes ts2))
+
+cmpPred :: PredType -> PredType -> Ordering
+cmpPred p1 p2 = cmpPredX rn_env p1 p2
+ where
+ rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfPred p1 `unionVarSet` tyVarsOfPred p2))
--- Look through Notes, PredTy, newtype applications
-eq_ty env t1 t2 | Just t1' <- coreView t1 = eq_ty env t1' t2
-eq_ty env t1 t2 | Just t2' <- coreView t2 = eq_ty env t1 t2'
+cmpTypeX :: RnEnv2 -> Type -> Type -> Ordering -- Main workhorse
-- NB: we *cannot* short-cut the newtype comparison thus:
--- eq_ty env (NewTcApp tc1 tys1) (NewTcApp tc2 tys2)
--- | (tc1 == tc2) = (eq_tys env tys1 tys2)
+-- eqTypeX env (NewTcApp tc1 tys1) (NewTcApp tc2 tys2)
+-- | (tc1 == tc2) = (eqTypeXs env tys1 tys2)
--
-- Consider:
-- newtype T a = MkT [a]
-- but we can only expand saturated newtypes, so just comparing
-- T with [] won't do.
--- The rest is plain sailing
-eq_ty env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of
- Just tv1a -> tv1a == tv2
- Nothing -> tv1 == tv2
-eq_ty env (ForAllTy tv1 t1) (ForAllTy tv2 t2)
- | tv1 == tv2 = eq_ty (delVarEnv env tv1) t1 t2
- | otherwise = eq_ty (extendVarEnv env tv1 tv2) t1 t2
-eq_ty env (AppTy s1 t1) (AppTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2)
-eq_ty env (FunTy s1 t1) (FunTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2)
-eq_ty env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 == tc2) && (eq_tys env tys1 tys2)
-eq_ty env t1 t2 = False
-
-eq_tys env [] [] = True
-eq_tys env (t1:tys1) (t2:tys2) = (eq_ty env t1 t2) && (eq_tys env tys1 tys2)
-eq_tys env tys1 tys2 = False
+cmpTypeX env (TyVarTy tv1) (TyVarTy tv2) = rnOccL env tv1 `compare` rnOccR env tv2
+cmpTypeX env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTypeX (rnBndr2 env tv1 tv2) t1 t2
+cmpTypeX env (AppTy s1 t1) (AppTy s2 t2) = cmpTypeX env s1 s2 `thenCmp` cmpTypeX env t1 t2
+cmpTypeX env (FunTy s1 t1) (FunTy s2 t2) = cmpTypeX env s1 s2 `thenCmp` cmpTypeX env t1 t2
+cmpTypeX env (PredTy p1) (PredTy p2) = cmpPredX env p1 p2
+cmpTypeX env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` cmpTypesX env tys1 tys2
+cmpTypeX env (NoteTy _ t1) t2 = cmpTypeX env t1 t2
+cmpTypeX env t1 (NoteTy _ t2) = cmpTypeX env t1 t2
+
+ -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy < PredTy
+cmpTypeX env (AppTy _ _) (TyVarTy _) = GT
+
+cmpTypeX env (FunTy _ _) (TyVarTy _) = GT
+cmpTypeX env (FunTy _ _) (AppTy _ _) = GT
+
+cmpTypeX env (TyConApp _ _) (TyVarTy _) = GT
+cmpTypeX env (TyConApp _ _) (AppTy _ _) = GT
+cmpTypeX env (TyConApp _ _) (FunTy _ _) = GT
+
+cmpTypeX env (ForAllTy _ _) (TyVarTy _) = GT
+cmpTypeX env (ForAllTy _ _) (AppTy _ _) = GT
+cmpTypeX env (ForAllTy _ _) (FunTy _ _) = GT
+cmpTypeX env (ForAllTy _ _) (TyConApp _ _) = GT
+
+cmpTypeX env (PredTy _) t2 = GT
+
+cmpTypeX env _ _ = LT
+
+-------------
+cmpTypesX :: RnEnv2 -> [Type] -> [Type] -> Ordering
+cmpTypesX env [] [] = EQ
+cmpTypesX env (t1:tys1) (t2:tys2) = cmpTypeX env t1 t2 `compare` cmpTypesX env tys1 tys2
+cmpTypesX env [] tys = LT
+cmpTypesX env ty [] = GT
+
+-------------
+cmpPredX :: RnEnv2 -> PredType -> PredType -> Ordering
+cmpPredX env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` cmpTypeX env ty1 ty2
+ -- Compare types as well as names for implicit parameters
+ -- This comparison is used exclusively (I think) for the
+ -- finite map built in TcSimplify
+cmpPredX env (ClassP c1 tys1) (ClassP c2 tys2) = (c1 `compare` c2) `thenCmp` cmpTypesX env tys1 tys2
+cmpPredX env (IParam _ _) (ClassP _ _) = LT
+cmpPredX env (ClassP _ _) (IParam _ _) = GT
+\end{code}
+
+PredTypes are used as a FM key in TcSimplify,
+so we take the easy path and make them an instance of Ord
+
+\begin{code}
+instance Eq PredType where { (==) = tcEqPred }
+instance Ord PredType where { compare = tcCmpPred }
\end{code}
\begin{code}
module Unify (
-- Matching and unification
- matchTys, matchTyX, matchTysX,
+ matchTys, matchTyX, tcMatchPreds, MatchEnv(..),
+
unifyTys, unifyTysX,
- tcRefineTys, tcMatchTys, tcMatchPreds, coreRefineTys,
+ tcRefineTys, tcMatchTys, coreRefineTys,
-- Re-export
MaybeErr(..)
import VarEnv
import VarSet
import Kind ( isSubKind )
-import Type ( predTypeRep, typeKind,
- tyVarsOfType, tyVarsOfTypes, coreView,
- TvSubstEnv, TvSubst(..), substTy )
+import Type ( typeKind, tyVarsOfType, tyVarsOfTypes, tyVarsOfTheta,
+ TvSubstEnv, TvSubst(..), substTy, tcEqTypeX )
import TypeRep ( Type(..), PredType(..), funTyCon )
import Util ( snocView )
import ErrUtils ( Message )
%************************************************************************
%* *
- External interface
+ Matching
+%* *
+%************************************************************************
+
+
+Matching is much tricker than you might think.
+
+1. The substitution we generate binds the *template type variables*
+ which are given to us explicitly.
+
+2. We want to match in the presence of foralls;
+ e.g (forall a. t1) ~ (forall b. t2)
+
+ That is what the RnEnv2 is for; it does the alpha-renaming
+ that makes it as if a and b were the same variable.
+ Initialising the RnEnv2, so that it can generate a fresh
+ binder when necessary, entails knowing the free variables of
+ both types.
+
+3. We must be careful not to bind a template type variable to a
+ locally bound variable. E.g.
+ (forall a. x) ~ (forall b. b)
+ where x is the template type variable. Then we do not want to
+ bind x to a/b! This is a kind of occurs check.
+ The necessary locals accumulate in the RnEnv2.
+
+
+\begin{code}
+data MatchEnv
+ = ME { me_tmpls :: VarSet -- Template tyvars
+ , me_env :: RnEnv2 -- Renaming envt for nested foralls
+ } -- In-scope set includes template tyvars
+
+matchTys :: TyVarSet -- Template tyvars
+ -> [Type] -- Template
+ -> [Type] -- Target
+ -> Maybe TvSubstEnv -- One-shot; in principle the template
+ -- variables could be free in the target
+
+matchTys tmpls tys1 tys2
+ = match_tys (ME { me_tmpls = tmpls, me_env = mkRnEnv2 in_scope_tyvars})
+ emptyTvSubstEnv
+ tys1 tys2
+ where
+ in_scope_tyvars = mkInScopeSet (tmpls `unionVarSet` tyVarsOfTypes tys2)
+ -- We're assuming that all the interesting
+ -- tyvars in tys1 are in tmpls
+
+tcMatchPreds
+ :: [TyVar] -- Bind these
+ -> [PredType] -> [PredType]
+ -> Maybe TvSubstEnv
+tcMatchPreds tmpls ps1 ps2
+ = match_list (match_pred menv) emptyTvSubstEnv ps1 ps2
+ where
+ menv = ME { me_tmpls = mkVarSet tmpls, me_env = mkRnEnv2 in_scope_tyvars }
+ in_scope_tyvars = mkInScopeSet (tyVarsOfTheta ps1 `unionVarSet` tyVarsOfTheta ps2)
+
+matchTyX :: MatchEnv
+ -> TvSubstEnv -- Substitution to extend
+ -> Type -- Template
+ -> Type -- Target
+ -> Maybe TvSubstEnv
+
+matchTyX menv subst ty1 ty2 = match menv subst ty1 ty2 -- Rename for export
+\end{code}
+
+Now the internals of matching
+
+\begin{code}
+match :: MatchEnv -- For the ost part this is pushed downwards
+ -> TvSubstEnv -- Substitution so far:
+ -- Domain is subset of template tyvars
+ -- Free vars of range is subset of
+ -- in-scope set of the RnEnv2
+ -> Type -> Type -- Template and target respectively
+ -> Maybe TvSubstEnv
+-- This matcher works on source types; that is,
+-- it respects NewTypes and PredType
+
+match menv subst (NoteTy _ ty1) ty2 = match menv subst ty1 ty2
+match menv subst ty1 (NoteTy _ ty2) = match menv subst ty1 ty2
+
+match menv subst (TyVarTy tv1) ty2
+ | tv1 `elemVarSet` me_tmpls menv
+ = case lookupVarEnv subst tv1' of
+ Nothing | any (inRnEnvR rn_env) (varSetElems (tyVarsOfType ty2))
+ -> Nothing -- Occurs check
+ | otherwise
+ -> Just (extendVarEnv subst tv1 ty2)
+
+ Just ty1' | tcEqTypeX (nukeRnEnvL rn_env) ty1' ty2
+ -- ty1 has no locally-bound variables, hence nukeRnEnvL
+ -- Note tcEqType...we are doing source-type matching here
+ -> Just subst
+
+ other -> Nothing
+
+ | otherwise -- tv1 is not a template tyvar
+ = case ty2 of
+ TyVarTy tv2 | tv1' == rnOccR rn_env tv2 -> Just subst
+ other -> Nothing
+ where
+ rn_env = me_env menv
+ tv1' = rnOccL rn_env tv1
+
+match menv subst (ForAllTy tv1 ty1) (ForAllTy tv2 ty2)
+ = match menv' subst ty1 ty2
+ where -- Use the magic of rnBndr2 to go under the binders
+ menv' = menv { me_env = rnBndr2 (me_env menv) tv1 tv2 }
+
+match menv subst (PredTy p1) (PredTy p2)
+ = match_pred menv subst p1 p2
+match menv subst (TyConApp tc1 tys1) (TyConApp tc2 tys2)
+ | tc1 == tc2 = match_tys menv subst tys1 tys2
+match menv subst (FunTy ty1a ty1b) (FunTy ty2a ty2b)
+ = do { subst' <- match menv subst ty1a ty2a
+ ; match menv subst' ty1b ty2b }
+match menv subst (AppTy ty1a ty1b) ty2
+ | Just (ty2a, ty2b) <- repSplitAppTy_maybe ty2
+ = do { subst' <- match menv subst ty1a ty2a
+ ; match menv subst' ty1b ty2b }
+
+match menv subst ty1 ty2
+ = Nothing
+
+--------------
+match_tys menv subst tys1 tys2 = match_list (match menv) subst tys1 tys2
+
+--------------
+match_list :: (TvSubstEnv -> a -> a -> Maybe TvSubstEnv)
+ -> TvSubstEnv -> [a] -> [a] -> Maybe TvSubstEnv
+match_list fn subst [] [] = Just subst
+match_list fn subst (ty1:tys1) (ty2:tys2) = do { subst' <- fn subst ty1 ty2
+ ; match_list fn subst' tys1 tys2 }
+match_list fn subst tys1 tys2 = Nothing
+
+--------------
+match_pred menv subst (ClassP c1 tys1) (ClassP c2 tys2)
+ | c1 == c2 = match_tys menv subst tys1 tys2
+match_pred menv subst (IParam n1 t1) (IParam n2 t2)
+ | n1 == n2 = match menv subst t1 t2
+match_pred menv subst p1 p2 = Nothing
+\end{code}
+
+
+%************************************************************************
+%* *
+ The workhorse
%* *
%************************************************************************
\begin{code}
-----------------------------
tcRefineTys, tcMatchTys
:: [TyVar] -- Try to unify these
-> TvSubstEnv -- Not idempotent
-> [Type] -> [Type]
- -> MaybeErr TvSubstEnv Message -- Not idempotent
+ -> MaybeErr Message TvSubstEnv -- Not idempotent
-- This one is used by the type checker. Neither the input nor result
-- substitition is idempotent
tcRefineTys ex_tvs subst tys1 tys2
- = initUM (tryToBind (mkVarSet ex_tvs)) (unify_tys Src subst tys1 tys2)
+ = initUM (tryToBind (mkVarSet ex_tvs)) (unify_tys subst tys1 tys2)
tcMatchTys ex_tvs subst tys1 tys2
- = initUM (bindOnly (mkVarSet ex_tvs)) (unify_tys Src subst tys1 tys2)
-
-tcMatchPreds
- :: [TyVar] -- Bind these
- -> [PredType] -> [PredType]
- -> Maybe TvSubstEnv
-tcMatchPreds tvs preds1 preds2
- = maybeErrToMaybe $ initUM (bindOnly (mkVarSet tvs)) $
- unify_preds Src emptyVarEnv preds1 preds2
+ = initUM (bindOnly (mkVarSet ex_tvs)) (unify_tys subst tys1 tys2)
----------------------------
coreRefineTys :: [TyVar] -- Try to unify these
do { -- Apply the input substitution; nothing int ty2
let ty1' = substTy subst ty1
-- Run the unifier, starting with an empty env
- ; extra_env <- unify Src emptyTvSubstEnv ty1' ty2
+ ; extra_env <- unify emptyTvSubstEnv ty1' ty2
-- Find the fixed point of the resulting non-idempotent
-- substitution, and apply it to the
----------------------------
-matchTys :: TyVarSet -- Template tyvars
- -> [Type] -- Template
- -> [Type] -- Target
- -> Maybe TvSubstEnv -- Idempotent, because when matching
- -- the range and domain are distinct
-
--- PRE-CONDITION for matching: template variables are not free in the target
-
-matchTys tmpls tys1 tys2
- = ASSERT2( not (intersectsVarSet tmpls (tyVarsOfTypes tys2)),
- ppr tmpls $$ ppr tys1 $$ ppr tys2 )
- maybeErrToMaybe $ initUM (bindOnly tmpls)
- (unify_tys Src emptyTvSubstEnv tys1 tys2)
-
-matchTyX :: TyVarSet -- Template tyvars
- -> TvSubstEnv -- Idempotent substitution to extend
- -> Type -- Template
- -> Type -- Target
- -> Maybe TvSubstEnv -- Idempotent
-
-matchTyX tmpls env ty1 ty2
- = ASSERT( not (intersectsVarSet tmpls (tyVarsOfType ty2)) )
- maybeErrToMaybe $ initUM (bindOnly tmpls)
- (unify Src env ty1 ty2)
-
-matchTysX :: TyVarSet -- Template tyvars
- -> TvSubstEnv -- Idempotent substitution to extend
- -> [Type] -- Template
- -> [Type] -- Target
- -> Maybe TvSubstEnv -- Idempotent
-
-matchTysX tmpls env tys1 tys2
- = ASSERT( not (intersectsVarSet tmpls (tyVarsOfTypes tys2)) )
- maybeErrToMaybe $ initUM (bindOnly tmpls)
- (unify_tys Src env tys1 tys2)
-
-
-----------------------------
unifyTys :: TyVarSet -> [Type] -> [Type] -> Maybe TvSubstEnv
unifyTys bind_these tys1 tys2
= maybeErrToMaybe $ initUM (bindOnly bind_these) $
- unify_tys Src emptyTvSubstEnv tys1 tys2
+ unify_tys emptyTvSubstEnv tys1 tys2
unifyTysX :: TyVarSet -> TvSubstEnv -> [Type] -> [Type] -> Maybe TvSubstEnv
unifyTysX bind_these subst tys1 tys2
= maybeErrToMaybe $ initUM (bindOnly bind_these) $
- unify_tys Src subst tys1 tys2
+ unify_tys subst tys1 tys2
----------------------------
tryToBind, bindOnly :: TyVarSet -> TyVar -> BindFlag
%************************************************************************
\begin{code}
-unify :: SrcFlag -- True, unifying source types, false core types.
- -> TvSubstEnv -- An existing substitution to extend
+unify :: TvSubstEnv -- An existing substitution to extend
-> Type -> Type -- Types to be unified
-> UM TvSubstEnv -- Just the extended substitution,
-- Nothing if unification failed
-- nor guarantee that the outgoing one is. That's fixed up by
-- the wrappers.
-unify s subst ty1 ty2 = -- pprTrace "unify" (ppr subst <+> pprParendType ty1 <+> pprParendType ty2) $
- unify_ s subst (rep s ty1) (rep s ty2)
-
-rep :: SrcFlag -> Type -> Type -- Strip off the clutter
-rep Src (NoteTy _ ty) = rep Src ty
-rep Core ty | Just ty' <- coreView ty = rep Core ty'
-rep s ty = ty
+unify subst ty1 ty2 = -- pprTrace "unify" (ppr subst <+> pprParendType ty1 <+> pprParendType ty2) $
+ unify_ subst ty1 ty2
-- in unify_, any NewTcApps/Preds should be taken at face value
-unify_ s subst (TyVarTy tv1) ty2 = uVar s False subst tv1 ty2
-unify_ s subst ty1 (TyVarTy tv2) = uVar s True subst tv2 ty1
+unify_ subst (TyVarTy tv1) ty2 = uVar False subst tv1 ty2
+unify_ subst ty1 (TyVarTy tv2) = uVar True subst tv2 ty1
-unify_ s subst (PredTy p1) (PredTy p2) = unify_pred s subst p1 p2
+unify_ subst (PredTy p1) (PredTy p2) = unify_pred subst p1 p2
-unify_ s subst t1@(TyConApp tyc1 tys1) t2@(TyConApp tyc2 tys2)
- | tyc1 == tyc2 = unify_tys s subst tys1 tys2
+unify_ subst t1@(TyConApp tyc1 tys1) t2@(TyConApp tyc2 tys2)
+ | tyc1 == tyc2 = unify_tys subst tys1 tys2
-unify_ s subst (FunTy ty1a ty1b) (FunTy ty2a ty2b)
- = do { subst' <- unify s subst ty1a ty2a
- ; unify s subst' ty1b ty2b }
+unify_ subst (FunTy ty1a ty1b) (FunTy ty2a ty2b)
+ = do { subst' <- unify subst ty1a ty2a
+ ; unify subst' ty1b ty2b }
-- Applications need a bit of care!
-- They can match FunTy and TyConApp, so use splitAppTy_maybe
-- NB: we've already dealt with type variables and Notes,
-- so if one type is an App the other one jolly well better be too
-unify_ s subst (AppTy ty1a ty1b) ty2
- | Just (ty2a, ty2b) <- unifySplitAppTy_maybe ty2
- = do { subst' <- unify s subst ty1a ty2a
- ; unify s subst' ty1b ty2b }
+unify_ subst (AppTy ty1a ty1b) ty2
+ | Just (ty2a, ty2b) <- repSplitAppTy_maybe ty2
+ = do { subst' <- unify subst ty1a ty2a
+ ; unify subst' ty1b ty2b }
-unify_ s subst ty1 (AppTy ty2a ty2b)
- | Just (ty1a, ty1b) <- unifySplitAppTy_maybe ty1
- = do { subst' <- unify s subst ty1a ty2a
- ; unify s subst' ty1b ty2b }
+unify_ subst ty1 (AppTy ty2a ty2b)
+ | Just (ty1a, ty1b) <- repSplitAppTy_maybe ty1
+ = do { subst' <- unify subst ty1a ty2a
+ ; unify subst' ty1b ty2b }
-unify_ s subst ty1 ty2 = failWith (misMatch ty1 ty2)
+unify_ subst ty1 ty2 = failWith (misMatch ty1 ty2)
------------------------------
-unify_pred s subst (ClassP c1 tys1) (ClassP c2 tys2)
- | c1 == c2 = unify_tys s subst tys1 tys2
-unify_pred s subst (IParam n1 t1) (IParam n2 t2)
- | n1 == n2 = unify s subst t1 t2
+unify_pred subst (ClassP c1 tys1) (ClassP c2 tys2)
+ | c1 == c2 = unify_tys subst tys1 tys2
+unify_pred subst (IParam n1 t1) (IParam n2 t2)
+ | n1 == n2 = unify subst t1 t2
+unify_pred subst p1 p2 = failWith (misMatch (PredTy p1) (PredTy p2))
------------------------------
-unifySplitAppTy_maybe :: Type -> Maybe (Type,Type)
--- NoteTy is already dealt with; take NewTcApps at face value
-unifySplitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
-unifySplitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
-unifySplitAppTy_maybe (TyConApp tc tys) = case snocView tys of
- Just (tys', ty') -> Just (TyConApp tc tys', ty')
- Nothing -> Nothing
-unifySplitAppTy_maybe other = Nothing
-
-------------------------------
-unify_tys s = unifyList (unify s)
-
-unify_preds :: SrcFlag -> TvSubstEnv -> [PredType] -> [PredType] -> UM TvSubstEnv
-unify_preds s = unifyList (unify_pred s)
+unify_tys = unifyList unify
unifyList :: Outputable a
=> (TvSubstEnv -> a -> a -> UM TvSubstEnv)
go subst _ _ = failWith (lengthMisMatch orig_xs orig_ys)
------------------------------
-uVar :: SrcFlag -- True, unifying source types, false core types.
- -> Bool -- Swapped
+uVar :: Bool -- Swapped
-> TvSubstEnv -- An existing substitution to extend
-> TyVar -- Type variable to be unified
-> Type -- with this type
-> UM TvSubstEnv
-uVar s swap subst tv1 ty
+uVar swap subst tv1 ty
= -- check to see whether tv1 is refined
case (lookupVarEnv subst tv1) of
-- yes, call back into unify'
- Just ty' | swap -> unify s subst ty ty'
- | otherwise -> unify s subst ty' ty
+ Just ty' | swap -> unify subst ty ty'
+ | otherwise -> unify subst ty' ty
-- No, continue
Nothing -> uUnrefined subst tv1 ty
%************************************************************************
\begin{code}
-data SrcFlag = Src | Core -- Unifying at the source level, or core level?
-
data BindFlag = BindMe | AvoidMe | DontBindMe
-isCore Core = True
-isCore Src = False
-
newtype UM a = UM { unUM :: (TyVar -> BindFlag)
- -> MaybeErr a Message }
+ -> MaybeErr Message a }
instance Monad UM where
return a = UM (\tvs -> Succeeded a)
Failed err -> Failed err
Succeeded v -> unUM (k v) tvs)
-initUM :: (TyVar -> BindFlag) -> UM a -> MaybeErr a Message
+initUM :: (TyVar -> BindFlag) -> UM a -> MaybeErr Message a
initUM badtvs um = unUM um badtvs
tvBindFlag :: TyVar -> UM BindFlag
failWith :: Message -> UM a
failWith msg = UM (\tv_fn -> Failed msg)
-maybeErrToMaybe :: MaybeErr succ fail -> Maybe succ
+maybeErrToMaybe :: MaybeErr fail succ -> Maybe succ
maybeErrToMaybe (Succeeded a) = Just a
maybeErrToMaybe (Failed m) = Nothing
+
+------------------------------
+repSplitAppTy_maybe :: Type -> Maybe (Type,Type)
+-- Like Type.splitAppTy_maybe, but any coreView stuff is already done
+repSplitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
+repSplitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
+repSplitAppTy_maybe (TyConApp tc tys) = case snocView tys of
+ Just (tys', ty') -> Just (TyConApp tc tys', ty')
+ Nothing -> Nothing
+repSplitAppTy_maybe other = Nothing
\end{code}
module Maybes (
module Maybe, -- Re-export all of Maybe
- MaybeErr(..),
+ MaybeErr(..), -- Instance of Monad
+ failME,
orElse,
mapCatMaybes,
expectJust,
maybeToBool,
- thenMaybe, seqMaybe, returnMaybe, failMaybe,
-
- thenMaB, returnMaB, failMaB
-
+ thenMaybe, seqMaybe, returnMaybe, failMaybe
) where
#include "HsVersions.h"
%************************************************************************
\begin{code}
-data MaybeErr val err = Succeeded val | Failed err
-\end{code}
-
-\begin{code}
-thenMaB :: MaybeErr val1 err -> (val1 -> MaybeErr val2 err) -> MaybeErr val2 err
-thenMaB m k
- = case m of
- Succeeded v -> k v
- Failed e -> Failed e
+data MaybeErr err val = Succeeded val | Failed err
-returnMaB :: val -> MaybeErr val err
-returnMaB v = Succeeded v
+instance Monad (MaybeErr err) where
+ return v = Succeeded v
+ Succeeded v >>= k = k v
+ Failed e >>= k = Failed e
-failMaB :: err -> MaybeErr val err
-failMaB e = Failed e
+failME :: err -> MaybeErr err val
+failME e = Failed e
\end{code}
-
takeList, dropList, splitAtList,
-- comparisons
- eqListBy, equalLength, compareLength,
+ isEqual, eqListBy, equalLength, compareLength,
thenCmp, cmpList, prefixMatch, suffixMatch, maybePrefixMatch,
-- strictness
%************************************************************************
\begin{code}
+isEqual :: Ordering -> Bool
+-- Often used in (isEqual (a `compare` b))
+isEqual GT = False
+isEqual EQ = True
+isEqual LT = False
+
+thenCmp :: Ordering -> Ordering -> Ordering
+{-# INLINE thenCmp #-}
+thenCmp EQ any = any
+thenCmp other any = other
+
eqListBy :: (a->a->Bool) -> [a] -> [a] -> Bool
eqListBy eq [] [] = True
eqListBy eq (x:xs) (y:ys) = eq x y && eqListBy eq xs ys
compareLength [] _ys = LT
compareLength _xs [] = GT
-thenCmp :: Ordering -> Ordering -> Ordering
-{-# INLINE thenCmp #-}
-thenCmp EQ any = any
-thenCmp other any = other
-
cmpList :: (a -> a -> Ordering) -> [a] -> [a] -> Ordering
-- `cmpList' uses a user-specified comparer
projects / ghc-hetmet.git / commitdiff