ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts,
instLoc, getDictClassTys, dictPred,
- lookupInst, lookupSimpleInst, LookupInstResult(..),
+ lookupInst, LookupInstResult(..),
isDict, isClassDict, isMethod,
isLinearInst, linearInstType, isIPDict, isInheritableInst,
#include "HsVersions.h"
-import {-# SOURCE #-} TcExpr( tcExpr )
+import {-# SOURCE #-} TcExpr( tcCheckSigma )
import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) )
-import TcHsSyn ( TcExpr, TcId, TcIdSet, TypecheckedHsExpr,
- mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId
+import TcHsSyn ( TcExpr, TcId, TcIdSet,
+ mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId,
+ mkCoercion, ExprCoFn
)
import TcRnMonad
-import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon )
+import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon, checkWellStaged, topIdLvl )
import InstEnv ( InstLookupResult(..), lookupInstEnv )
-import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zapToType,
+import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType,
zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars
)
import TcType ( Type, TcType, TcThetaType, TcTyVarSet,
- SourceType(..), PredType, ThetaType, TyVarDetails(VanillaTv),
+ SourceType(..), PredType, TyVarDetails(VanillaTv),
tcSplitForAllTys, tcSplitForAllTys, mkTyConApp,
- tcSplitMethodTy, tcSplitPhiTy, mkGenTyConApp,
+ tcSplitPhiTy, mkGenTyConApp,
isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys,
tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
- isClassPred, isTyVarClassPred, isLinearPred, predHasFDs,
+ isClassPred, isTyVarClassPred, isLinearPred,
getClassPredTys, getClassPredTys_maybe, mkPredName,
isInheritablePred, isIPPred,
tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy
)
import CoreFVs ( idFreeTyVars )
-import Class ( Class )
import DataCon ( DataCon,dataConSig )
import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId, setIdUnique )
import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
import Name ( Name, mkMethodOcc, getOccName )
import PprType ( pprPred, pprParendType )
-import Subst ( emptyInScopeSet, mkSubst, substTy, substTyWith, substTheta, mkTyVarSubst )
+import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst )
import Literal ( inIntRange )
import Var ( TyVar )
import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) )
import VarSet ( elemVarSet, emptyVarSet, unionVarSet )
import TysWiredIn ( floatDataCon, doubleDataCon )
import PrelNames( fromIntegerName, fromRationalName, rationalTyConName )
-import Util ( equalLength )
import BasicTypes( IPName(..), mapIPName, ipNameName )
import UniqSupply( uniqsFromSupply )
import Outputable
getDictClassTys (Dict _ pred _) = getClassPredTys pred
-- fdPredsOfInst is used to get predicates that contain functional
--- dependencies; i.e. should participate in improvement
-fdPredsOfInst (Dict _ pred _) | predHasFDs pred = [pred]
- | otherwise = []
-fdPredsOfInst (Method _ _ _ theta _ _) = filter predHasFDs theta
-fdPredsOfInst other = []
+-- dependencies *or* might do so. The "might do" part is because
+-- a constraint (C a b) might have a superclass with FDs
+-- Leaving these in is really important for the call to fdPredsOfInsts
+-- in TcSimplify.inferLoop, because the result is fed to 'grow',
+-- which is supposed to be conservative
+fdPredsOfInst (Dict _ pred _) = [pred]
+fdPredsOfInst (Method _ _ _ theta _ _) = theta
+fdPredsOfInst other = [] -- LitInsts etc
fdPredsOfInsts :: [Inst] -> [PredType]
fdPredsOfInsts insts = concatMap fdPredsOfInst insts
\begin{code}
-tcInstCall :: InstOrigin -> TcType -> TcM (TypecheckedHsExpr -> TypecheckedHsExpr, TcType)
+tcInstCall :: InstOrigin -> TcType -> TcM (ExprCoFn, TcType)
tcInstCall orig fun_ty -- fun_ty is usually a sigma-type
= tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
newDicts orig theta `thenM` \ dicts ->
let
inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts)
in
- returnM (inst_fn, tau)
+ returnM (mkCoercion inst_fn, tau)
tcInstDataCon :: InstOrigin -> DataCon
-> TcM ([TcType], -- Types to instantiate at
-- to simplify Insts
tcInstClassOp :: InstLoc -> Id -> [TcType] -> TcM Inst
- -- Instantiate the specified class op, but *only* with the main
- -- class dictionary. For example, given 'op' defined thus:
- -- class Foo a where
- -- op :: (?x :: String) => a -> a
- -- (tcInstClassOp op T) should return an Inst with type
- -- (?x :: String) => T -> T
- -- That is, the class-op's context is still there.
- -- This is really important in the use of tcInstClassOp in TcClassDcls.mkMethodBind
tcInstClassOp inst_loc sel_id tys
= let
(tyvars,rho) = tcSplitForAllTys (idType sel_id)
- rho_ty = substTyWith tyvars tys rho
- (pred,tau) = tcSplitMethodTy rho_ty
- -- Split off exactly one predicate (see the example above)
+ rho_ty = ASSERT( length tyvars == length tys )
+ substTyWith tyvars tys rho
+ (preds,tau) = tcSplitPhiTy rho_ty
in
- ASSERT( isClassPred pred )
- newMethod inst_loc sel_id tys [pred] tau
+ newMethod inst_loc sel_id tys preds tau
---------------------------
newMethod inst_loc id tys theta tau
| fi /= fromIntegerName -- Do not generate a LitInst for rebindable
-- syntax. Reason: tcSyntaxName does unification
-- which is very inconvenient in tcSimplify
- = tcSyntaxName orig expected_ty fromIntegerName fi `thenM` \ (expr, _) ->
+ = tcSyntaxName orig expected_ty (fromIntegerName, HsVar fi) `thenM` \ (_,expr) ->
returnM (HsApp expr (HsLit (HsInteger i)))
| Just expr <- shortCutIntLit i expected_ty
newOverloadedLit orig lit@(HsFractional r fr) expected_ty
| fr /= fromRationalName -- c.f. HsIntegral case
- = tcSyntaxName orig expected_ty fromRationalName fr `thenM` \ (expr, _) ->
- mkRatLit r `thenM` \ rat_lit ->
+ = tcSyntaxName orig expected_ty (fromRationalName, HsVar fr) `thenM` \ (_,expr) ->
+ mkRatLit r `thenM` \ rat_lit ->
returnM (HsApp expr rat_lit)
| Just expr <- shortCutFracLit r expected_ty
newLitInst orig lit expected_ty
= getInstLoc orig `thenM` \ loc ->
newUnique `thenM` \ new_uniq ->
- zapToType expected_ty `thenM_`
- -- The expected type might be a 'hole' type variable,
- -- in which case we must zap it to an ordinary type variable
let
lit_inst = LitInst lit_id lit expected_ty loc
lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty
pprInstsInFull insts
= vcat (map go insts)
where
- go inst = quotes (ppr inst) <+> pprInstLoc (instLoc inst)
+ go inst = sep [quotes (ppr inst), nest 2 (pprInstLoc (instLoc inst))]
pprInst (LitInst u lit ty loc)
= hsep [ppr lit, ptext SLIT("at"), ppr ty, show_uniq u]
tidyInsts :: [Inst] -> (TidyEnv, [Inst])
tidyInsts insts = tidyMoreInsts emptyTidyEnv insts
-showLIE :: String -> TcM () -- Debugging
+showLIE :: SDoc -> TcM () -- Debugging
showLIE str
= do { lie_var <- getLIEVar ;
lie <- readMutVar lie_var ;
- traceTc (text str <+> pprInstsInFull (lieToList lie)) }
+ traceTc (str <+> pprInstsInFull (lieToList lie)) }
\end{code}
-- Dictionaries
-lookupInst dict@(Dict _ (ClassP clas tys) loc)
+lookupInst dict@(Dict _ pred@(ClassP clas tys) loc)
= getDOpts `thenM` \ dflags ->
tcGetInstEnv `thenM` \ inst_env ->
case lookupInstEnv dflags inst_env clas tys of
-- instance C X a => D X where ...
-- (presumably there's a functional dependency in class C)
-- Hence the mk_ty_arg to instantiate any un-substituted tyvars.
+ getStage `thenM` \ use_stage ->
+ checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred))
+ (topIdLvl dfun_id) use_stage `thenM_`
+ traceTc (text "lookupInst" <+> ppr dfun_id <+> ppr (topIdLvl dfun_id) <+> ppr use_stage) `thenM_`
let
(tyvars, rho) = tcSplitForAllTys (idType dfun_id)
mk_ty_arg tv = case lookupSubstEnv tenv tv of
returnM (GenInst [method_inst] (HsApp (HsVar (instToId method_inst)) rat_lit))
\end{code}
-There is a second, simpler interface, when you want an instance of a
-class at a given nullary type constructor. It just returns the
-appropriate dictionary if it exists. It is used only when resolving
-ambiguous dictionaries.
-
-\begin{code}
-lookupSimpleInst :: Class
- -> [Type] -- Look up (c,t)
- -> TcM (Maybe ThetaType) -- Here are the needed (c,t)s
-
-lookupSimpleInst clas tys
- = getDOpts `thenM` \ dflags ->
- tcGetInstEnv `thenM` \ inst_env ->
- case lookupInstEnv dflags inst_env clas tys of
- FoundInst tenv dfun
- -> returnM (Just (substTheta (mkSubst emptyInScopeSet tenv) theta))
- where
- (_, rho) = tcSplitForAllTys (idType dfun)
- (theta,_) = tcSplitPhiTy rho
-
- other -> returnM Nothing
-\end{code}
%************************************************************************
\begin{code}
tcSyntaxName :: InstOrigin
-> TcType -- Type to instantiate it at
- -> Name -> Name -- (Standard name, user name)
- -> TcM (TcExpr, TcType) -- Suitable expression with its type
+ -> (Name, HsExpr Name) -- (Standard name, user name)
+ -> TcM (Name, TcExpr) -- (Standard name, suitable expression)
-- NB: tcSyntaxName calls tcExpr, and hence can do unification.
-- So we do not call it from lookupInst, which is called from tcSimplify
-tcSyntaxName orig ty std_nm user_nm
+tcSyntaxName orig ty (std_nm, HsVar user_nm)
| std_nm == user_nm
= newMethodFromName orig ty std_nm `thenM` \ id ->
- returnM (HsVar id, idType id)
+ returnM (std_nm, HsVar id)
- | otherwise
+tcSyntaxName orig ty (std_nm, user_nm_expr)
= tcLookupId std_nm `thenM` \ std_id ->
let
-- C.f. newMethodAtLoc
([tv], _, tau) = tcSplitSigmaTy (idType std_id)
tau1 = substTyWith [tv] [ty] tau
+ -- Actually, the "tau-type" might be a sigma-type in the
+ -- case of locally-polymorphic methods.
in
- addErrCtxtM (syntaxNameCtxt user_nm orig tau1) $
- tcExpr (HsVar user_nm) tau1 `thenM` \ user_fn ->
- returnM (user_fn, tau1)
+ addErrCtxtM (syntaxNameCtxt user_nm_expr orig tau1) $
+ tcCheckSigma user_nm_expr tau1 `thenM` \ expr ->
+ returnM (std_nm, expr)
syntaxNameCtxt name orig ty tidy_env
= getInstLoc orig `thenM` \ inst_loc ->
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