X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=562510e8474f3584f29af79a28a2292117352c81;hb=98688c6e8fd33f31c51218cf93cbf03fe3a5e73d;hp=0f693717993a233fb8fe516c616ddb93377baa41;hpb=3355c9d53b220ccb110e5a3c81a1a8b2c9c41555;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 0f69371..562510e 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -4,27 +4,26 @@ \section[TcExpr]{Typecheck an expression} \begin{code} -module TcExpr ( tcExpr, tcExpr_id, tcMonoExpr ) where +module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where #include "HsVersions.h" #ifdef GHCI /* Only if bootstrapped */ import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket ) import HsSyn ( HsReify(..), ReifyFlavour(..) ) +import Id ( Id ) import TcType ( isTauTy ) -import TcEnv ( bracketOK, tcMetaTy, checkWellStaged, metaLevel ) -import TcSimplify ( tcSimplifyBracket ) -import Name ( isExternalName ) +import TcEnv ( tcMetaTy, checkWellStaged ) import qualified DsMeta #endif -import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), recBindFields ) +import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), recBindFields, + HsMatchContext(..) ) import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds ) -import TcHsSyn ( TcExpr, TcRecordBinds, hsLitType, mkHsDictApp, mkHsTyApp, mkHsLet ) +import TcHsSyn ( TcExpr, TcRecordBinds, hsLitType, mkHsDictApp, mkHsTyApp, (<$>) ) import TcRnMonad -import TcUnify ( tcSubExp, tcGen, (<$>), - unifyTauTy, unifyFunTy, unifyListTy, unifyPArrTy, - unifyTupleTy ) +import TcUnify ( Expected(..), newHole, zapExpectedType, zapExpectedTo, tcSubExp, tcGen, + unifyFunTy, zapToListTy, zapToPArrTy, zapToTupleTy ) import BasicTypes ( isMarkedStrict ) import Inst ( InstOrigin(..), newOverloadedLit, newMethodFromName, newIPDict, @@ -32,36 +31,32 @@ import Inst ( InstOrigin(..), instToId, tcInstCall, tcInstDataCon ) import TcBinds ( tcBindsAndThen ) -import TcEnv ( tcLookupClass, tcLookupGlobal_maybe, tcLookupIdLvl, - tcLookupTyCon, tcLookupDataCon, tcLookupId +import TcEnv ( tcLookup, tcLookupGlobalId, + tcLookupDataCon, tcLookupId, checkProcLevel ) -import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts ) -import TcMonoType ( tcHsSigType, UserTypeCtxt(..) ) +import TcArrows ( tcProc ) +import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) ) +import TcHsType ( tcHsSigType, UserTypeCtxt(..) ) import TcPat ( badFieldCon ) -import TcMType ( tcInstTyVars, tcInstType, newHoleTyVarTy, zapToType, - newTyVarTy, newTyVarTys, zonkTcType, readHoleResult ) +import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, zonkTcType ) import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv), tcSplitFunTys, tcSplitTyConApp, mkTyVarTys, isSigmaTy, mkFunTy, mkFunTys, - mkTyConApp, mkClassPred, tcFunArgTy, - tyVarsOfTypes, isLinearPred, + mkTyConApp, tyVarsOfTypes, isLinearPred, liftedTypeKind, openTypeKind, - tcSplitSigmaTy, tcTyConAppTyCon, - tidyOpenType + tcSplitSigmaTy, tidyOpenType ) import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon ) -import Id ( Id, idType, recordSelectorFieldLabel, isRecordSelector ) -import DataCon ( DataCon, dataConFieldLabels, dataConSig, dataConStrictMarks, dataConWrapId ) +import Id ( idType, recordSelectorFieldLabel, isRecordSelector ) +import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId ) import Name ( Name ) -import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons, isClassTyCon ) +import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons ) import Subst ( mkTopTyVarSubst, substTheta, substTy ) import VarSet ( emptyVarSet, elemVarSet ) import TysWiredIn ( boolTy ) -import PrelNames ( cCallableClassName, cReturnableClassName, - enumFromName, enumFromThenName, +import PrelNames ( enumFromName, enumFromThenName, enumFromToName, enumFromThenToName, - enumFromToPName, enumFromThenToPName, - ioTyConName + enumFromToPName, enumFromThenToPName ) import ListSetOps ( minusList ) import CmdLineOpts @@ -79,25 +74,44 @@ import FastString %************************************************************************ \begin{code} -tcExpr :: RenamedHsExpr -- Expession to type check - -> TcSigmaType -- Expected type (could be a polytpye) - -> TcM TcExpr -- Generalised expr with expected type +-- tcCheckSigma does type *checking*; it's passed the expected type of the result +tcCheckSigma :: RenamedHsExpr -- Expession to type check + -> TcSigmaType -- Expected type (could be a polytpye) + -> TcM TcExpr -- Generalised expr with expected type -tcExpr expr expected_ty +tcCheckSigma expr expected_ty = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_` tc_expr' expr expected_ty -tc_expr' expr expected_ty - | not (isSigmaTy expected_ty) -- Monomorphic case - = tcMonoExpr expr expected_ty - - | otherwise - = tcGen expected_ty emptyVarSet ( - tcMonoExpr expr +tc_expr' expr sigma_ty + | isSigmaTy sigma_ty + = tcGen sigma_ty emptyVarSet ( + \ rho_ty -> tcCheckRho expr rho_ty ) `thenM` \ (gen_fn, expr') -> returnM (gen_fn <$> expr') + +tc_expr' expr rho_ty -- Monomorphic case + = tcCheckRho expr rho_ty \end{code} +Typecheck expression which in most cases will be an Id. +The expression can return a higher-ranked type, such as + (forall a. a->a) -> Int +so we must create a hole to pass in as the expected tyvar. + +\begin{code} +tcCheckRho :: RenamedHsExpr -> TcRhoType -> TcM TcExpr +tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty) + +tcInferRho :: RenamedHsExpr -> TcM (TcExpr, TcRhoType) +tcInferRho (HsVar name) = tcId name +tcInferRho expr = newHole `thenM` \ hole -> + tcMonoExpr expr (Infer hole) `thenM` \ expr' -> + readMutVar hole `thenM` \ rho_ty -> + returnM (expr', rho_ty) +\end{code} + + %************************************************************************ %* * @@ -107,7 +121,7 @@ tc_expr' expr expected_ty \begin{code} tcMonoExpr :: RenamedHsExpr -- Expession to type check - -> TcRhoType -- Expected type (could be a type variable) + -> Expected TcRhoType -- Expected type (could be a type variable) -- Definitely no foralls at the top -- Can be a 'hole'. -> TcM TcExpr @@ -138,17 +152,10 @@ tcMonoExpr (HsIPVar ip) res_ty \begin{code} tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty - = addErrCtxt (exprSigCtxt in_expr) $ - tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty -> - tcExpr expr sig_tc_ty `thenM` \ expr' -> - - -- Must instantiate the outer for-alls of sig_tc_ty - -- else we risk instantiating a ? res_ty to a forall-type - -- which breaks the invariant that tcMonoExpr only returns phi-types - tcInstCall SignatureOrigin sig_tc_ty `thenM` \ (inst_fn, inst_sig_ty) -> - tcSubExp res_ty inst_sig_ty `thenM` \ co_fn -> - - returnM (co_fn <$> inst_fn expr') + = addErrCtxt (exprSigCtxt in_expr) $ + tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty -> + tcThingWithSig sig_tc_ty (tcCheckRho expr) res_ty `thenM` \ (co_fn, expr') -> + returnM (co_fn <$> expr') tcMonoExpr (HsType ty) res_ty = failWithTc (text "Can't handle type argument:" <+> ppr ty) @@ -168,13 +175,15 @@ tcMonoExpr (HsType ty) res_ty \begin{code} tcMonoExpr (HsLit lit) res_ty = tcLit lit res_ty -tcMonoExpr (HsOverLit lit) res_ty = newOverloadedLit (LiteralOrigin lit) lit res_ty +tcMonoExpr (HsOverLit lit) res_ty = zapExpectedType res_ty `thenM` \ res_ty' -> + newOverloadedLit (LiteralOrigin lit) lit res_ty' tcMonoExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> returnM (HsPar expr') tcMonoExpr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> returnM (HsSCC lbl expr') - +tcMonoExpr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation + returnM (HsCoreAnn lbl expr') tcMonoExpr (NegApp expr neg_name) res_ty = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty -- ToDo: use tcSyntaxName @@ -199,7 +208,7 @@ a type error will occur if they aren't. -- op e tcMonoExpr in_expr@(SectionL arg1 op) res_ty - = tcExpr_id op `thenM` \ (op', op_ty) -> + = tcInferRho op `thenM` \ (op', op_ty) -> split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' -> addErrCtxt (exprCtxt in_expr) $ @@ -210,7 +219,7 @@ tcMonoExpr in_expr@(SectionL arg1 op) res_ty -- \ x -> op x expr tcMonoExpr in_expr@(SectionR op arg2) res_ty - = tcExpr_id op `thenM` \ (op', op_ty) -> + = tcInferRho op `thenM` \ (op', op_ty) -> split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' -> addErrCtxt (exprCtxt in_expr) $ @@ -220,7 +229,7 @@ tcMonoExpr in_expr@(SectionR op arg2) res_ty -- equivalent to (op e1) e2: tcMonoExpr in_expr@(OpApp arg1 op fix arg2) res_ty - = tcExpr_id op `thenM` \ (op', op_ty) -> + = tcInferRho op `thenM` \ (op', op_ty) -> split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' -> tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' -> @@ -246,128 +255,66 @@ tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty -- case (map f) of -- (x:xs) -> ... -- will report that map is applied to too few arguments - -- - -- Not only that, but it's better to check the matches on their - -- own, so that we get the expected results for scoped type variables. - -- f x = case x of - -- (p::a, q::b) -> (q,p) - -- The above should work: the match (p,q) -> (q,p) is polymorphic as - -- claimed by the pattern signatures. But if we typechecked the - -- match with x in scope and x's type as the expected type, we'd be hosed. - tcMatchesCase matches res_ty `thenM` \ (scrut_ty, matches') -> + tcMatchesCase match_ctxt matches res_ty `thenM` \ (scrut_ty, matches') -> addErrCtxt (caseScrutCtxt scrut) ( - tcMonoExpr scrut scrut_ty + tcCheckRho scrut scrut_ty ) `thenM` \ scrut' -> returnM (HsCase scrut' matches' src_loc) + where + match_ctxt = MC { mc_what = CaseAlt, + mc_body = tcMonoExpr } tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty = addSrcLoc src_loc $ addErrCtxt (predCtxt pred) ( - tcMonoExpr pred boolTy ) `thenM` \ pred' -> + tcCheckRho pred boolTy ) `thenM` \ pred' -> - zapToType res_ty `thenM` \ res_ty' -> + zapExpectedType res_ty `thenM` \ res_ty' -> -- C.f. the call to zapToType in TcMatches.tcMatches - tcMonoExpr b1 res_ty' `thenM` \ b1' -> - tcMonoExpr b2 res_ty' `thenM` \ b2' -> + tcCheckRho b1 res_ty' `thenM` \ b1' -> + tcCheckRho b2 res_ty' `thenM` \ b2' -> returnM (HsIf pred' b1' b2' src_loc) tcMonoExpr (HsDo do_or_lc stmts method_names _ src_loc) res_ty - = addSrcLoc src_loc $ - tcDoStmts do_or_lc stmts method_names res_ty `thenM` \ (binds, stmts', methods') -> - returnM (mkHsLet binds (HsDo do_or_lc stmts' methods' res_ty src_loc)) + = addSrcLoc src_loc $ + zapExpectedType res_ty `thenM` \ res_ty' -> + -- All comprehensions yield a monotype + tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') -> + returnM (HsDo do_or_lc stmts' methods' res_ty' src_loc) tcMonoExpr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list - = unifyListTy res_ty `thenM` \ elt_ty -> + = zapToListTy res_ty `thenM` \ elt_ty -> mappM (tc_elt elt_ty) exprs `thenM` \ exprs' -> returnM (ExplicitList elt_ty exprs') where tc_elt elt_ty expr = addErrCtxt (listCtxt expr) $ - tcMonoExpr expr elt_ty + tcCheckRho expr elt_ty tcMonoExpr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty - = unifyPArrTy res_ty `thenM` \ elt_ty -> + = zapToPArrTy res_ty `thenM` \ elt_ty -> mappM (tc_elt elt_ty) exprs `thenM` \ exprs' -> returnM (ExplicitPArr elt_ty exprs') where tc_elt elt_ty expr = addErrCtxt (parrCtxt expr) $ - tcMonoExpr expr elt_ty + tcCheckRho expr elt_ty tcMonoExpr (ExplicitTuple exprs boxity) res_ty - = unifyTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys -> - tcMonoExprs exprs arg_tys `thenM` \ exprs' -> + = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys -> + tcCheckRhos exprs arg_tys `thenM` \ exprs' -> returnM (ExplicitTuple exprs' boxity) -\end{code} - -%************************************************************************ -%* * - Foreign calls -%* * -%************************************************************************ - -The interesting thing about @ccall@ is that it is just a template -which we instantiate by filling in details about the types of its -argument and result (ie minimal typechecking is performed). So, the -basic story is that we allocate a load of type variables (to hold the -arg/result types); unify them with the args/result; and store them for -later use. - -\begin{code} -tcMonoExpr e0@(HsCCall lbl args may_gc is_casm ignored_fake_result_ty) res_ty - - = getDOpts `thenM` \ dflags -> - - checkTc (not (is_casm && dopt_HscLang dflags /= HscC)) - (vcat [text "_casm_ is only supported when compiling via C (-fvia-C).", - text "Either compile with -fvia-C, or, better, rewrite your code", - text "to use the foreign function interface. _casm_s are deprecated", - text "and support for them may one day disappear."]) - `thenM_` - - -- Get the callable and returnable classes. - tcLookupClass cCallableClassName `thenM` \ cCallableClass -> - tcLookupClass cReturnableClassName `thenM` \ cReturnableClass -> - tcLookupTyCon ioTyConName `thenM` \ ioTyCon -> - let - new_arg_dict (arg, arg_ty) - = newDicts (CCallOrigin (unpackFS lbl) (Just arg)) - [mkClassPred cCallableClass [arg_ty]] `thenM` \ arg_dicts -> - returnM arg_dicts -- Actually a singleton bag - - result_origin = CCallOrigin (unpackFS lbl) Nothing {- Not an arg -} - in - - -- Arguments - let tv_idxs | null args = [] - | otherwise = [1..length args] - in - newTyVarTys (length tv_idxs) openTypeKind `thenM` \ arg_tys -> - tcMonoExprs args arg_tys `thenM` \ args' -> - - -- The argument types can be unlifted or lifted; the result - -- type must, however, be lifted since it's an argument to the IO - -- type constructor. - newTyVarTy liftedTypeKind `thenM` \ result_ty -> - let - io_result_ty = mkTyConApp ioTyCon [result_ty] - in - unifyTauTy res_ty io_result_ty `thenM_` - - -- Construct the extra insts, which encode the - -- constraints on the argument and result types. - mappM new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenM` \ ccarg_dicts_s -> - newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenM` \ ccres_dict -> - extendLIEs (ccres_dict ++ concat ccarg_dicts_s) `thenM_` - returnM (HsCCall lbl args' may_gc is_casm io_result_ty) +tcMonoExpr (HsProc pat cmd loc) res_ty + = addSrcLoc loc $ + tcProc pat cmd res_ty `thenM` \ (pat', cmd') -> + returnM (HsProc pat' cmd' loc) \end{code} - %************************************************************************ %* * Record construction and update @@ -383,11 +330,11 @@ tcMonoExpr expr@(RecordCon con_name rbinds) res_ty (tycon, ty_args) = tcSplitTyConApp record_ty in ASSERT( isAlgTyCon tycon ) - unifyTauTy res_ty record_ty `thenM_` + zapExpectedTo res_ty record_ty `thenM_` -- Check that the record bindings match the constructor -- con_name is syntactically constrained to be a data constructor - tcLookupDataCon con_name `thenM` \ data_con -> + tcLookupDataCon con_name `thenM` \ data_con -> let bad_fields = badFields rbinds data_con in @@ -439,14 +386,14 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty let field_names = recBindFields rbinds in - mappM tcLookupGlobal_maybe field_names `thenM` \ maybe_sel_ids -> + mappM tcLookupGlobalId field_names `thenM` \ sel_ids -> + -- The renamer has already checked that they + -- are all in scope let bad_guys = [ addErrTc (notSelector field_name) - | (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids, - not (is_selector maybe_sel_id) + | (field_name, sel_id) <- field_names `zip` sel_ids, + not (isRecordSelector sel_id) -- Excludes class ops ] - is_selector (Just (AnId sel_id)) = isRecordSelector sel_id -- Excludes class ops - is_selector other = False in checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_` @@ -454,7 +401,7 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty -- Figure out the tycon and data cons from the first field name let -- It's OK to use the non-tc splitters here (for a selector) - (Just (AnId sel_id) : _) = maybe_sel_ids + sel_id : _ = sel_ids field_lbl = recordSelectorFieldLabel sel_id -- We've failed already if tycon = fieldLabelTyCon field_lbl -- it's not a field label data_cons = tyConDataCons tycon @@ -475,7 +422,7 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty let result_record_ty = mkTyConApp tycon result_inst_tys in - unifyTauTy res_ty result_record_ty `thenM_` + zapExpectedTo res_ty result_record_ty `thenM_` tcRecordBinds tycon result_inst_tys rbinds `thenM` \ rbinds' -> -- STEP 4 @@ -507,7 +454,7 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty let record_ty = mkTyConApp tycon inst_tys in - tcMonoExpr record_expr record_ty `thenM` \ record_expr' -> + tcCheckRho record_expr record_ty `thenM` \ record_expr' -> -- STEP 6 -- Figure out the LIE we need. We have to generate some @@ -537,8 +484,8 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty \begin{code} tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty - = unifyListTy res_ty `thenM` \ elt_ty -> - tcMonoExpr expr elt_ty `thenM` \ expr' -> + = zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr elt_ty `thenM` \ expr' -> newMethodFromName (ArithSeqOrigin seq) elt_ty enumFromName `thenM` \ enum_from -> @@ -547,9 +494,9 @@ tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty = addErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenM` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenM` \ expr1' -> - tcMonoExpr expr2 elt_ty `thenM` \ expr2' -> + zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> newMethodFromName (ArithSeqOrigin seq) elt_ty enumFromThenName `thenM` \ enum_from_then -> @@ -558,9 +505,9 @@ tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty = addErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenM` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenM` \ expr1' -> - tcMonoExpr expr2 elt_ty `thenM` \ expr2' -> + zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> newMethodFromName (ArithSeqOrigin seq) elt_ty enumFromToName `thenM` \ enum_from_to -> @@ -568,10 +515,10 @@ tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty = addErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenM` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenM` \ expr1' -> - tcMonoExpr expr2 elt_ty `thenM` \ expr2' -> - tcMonoExpr expr3 elt_ty `thenM` \ expr3' -> + zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> + tcCheckRho expr3 elt_ty `thenM` \ expr3' -> newMethodFromName (ArithSeqOrigin seq) elt_ty enumFromThenToName `thenM` \ eft -> @@ -579,9 +526,9 @@ tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty tcMonoExpr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty = addErrCtxt (parrSeqCtxt in_expr) $ - unifyPArrTy res_ty `thenM` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenM` \ expr1' -> - tcMonoExpr expr2 elt_ty `thenM` \ expr2' -> + zapToPArrTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> newMethodFromName (PArrSeqOrigin seq) elt_ty enumFromToPName `thenM` \ enum_from_to -> @@ -589,10 +536,10 @@ tcMonoExpr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty tcMonoExpr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty = addErrCtxt (parrSeqCtxt in_expr) $ - unifyPArrTy res_ty `thenM` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenM` \ expr1' -> - tcMonoExpr expr2 elt_ty `thenM` \ expr2' -> - tcMonoExpr expr3 elt_ty `thenM` \ expr3' -> + zapToPArrTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> + tcCheckRho expr3 elt_ty `thenM` \ expr3' -> newMethodFromName (PArrSeqOrigin seq) elt_ty enumFromThenToPName `thenM` \ eft -> @@ -616,19 +563,19 @@ tcMonoExpr (PArrSeqIn _) _ -- Rename excludes these cases otherwise tcMonoExpr (HsSplice n expr loc) res_ty = addSrcLoc loc (tcSpliceExpr n expr res_ty) -tcMonoExpr (HsBracket brack loc) res_ty = addSrcLoc loc (tcBracket brack) +tcMonoExpr (HsBracket brack loc) res_ty = addSrcLoc loc (tcBracket brack res_ty) tcMonoExpr (HsReify (Reify flavour name)) res_ty = addErrCtxt (ptext SLIT("At the reification of") <+> ppr name) $ - tcMetaTy tycon_name `thenM` \ reify_ty -> - unifyTauTy res_ty reify_ty `thenM_` + tcMetaTy tycon_name `thenM` \ reify_ty -> + zapExpectedTo res_ty reify_ty `thenM_` returnM (HsReify (ReifyOut flavour name)) where tycon_name = case flavour of - ReifyDecl -> DsMeta.declTyConName - ReifyType -> DsMeta.typeTyConName + ReifyDecl -> DsMeta.decQTyConName + ReifyType -> DsMeta.typeQTyConName ReifyFixity -> pprPanic "tcMonoExpr: cant do reifyFixity yet" (ppr name) -#endif GHCI +#endif /* GHCI */ \end{code} @@ -652,7 +599,7 @@ tcMonoExpr other _ = pprPanic "tcMonoExpr" (ppr other) \begin{code} tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args - -> TcType -- Expected result type of application + -> Expected TcRhoType -- Expected result type of application -> TcM TcExpr -- Translated fun and args tcApp (HsApp e1 e2) args res_ty @@ -660,32 +607,50 @@ tcApp (HsApp e1 e2) args res_ty tcApp fun args res_ty = -- First type-check the function - tcExpr_id fun `thenM` \ (fun', fun_ty) -> + tcInferRho fun `thenM` \ (fun', fun_ty) -> addErrCtxt (wrongArgsCtxt "too many" fun args) ( traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_` split_fun_ty fun_ty (length args) ) `thenM` \ (expected_arg_tys, actual_result_ty) -> - -- Now typecheck the args - mappM (tcArg fun) - (zip3 args expected_arg_tys [1..]) `thenM` \ args' -> - - -- Unify with expected result after type-checking the args - -- so that the info from args percolates to actual_result_ty. + -- Unify with expected result before (was: after) type-checking the args + -- so that the info from res_ty (was: args) percolates to args (was actual_result_ty). -- This is when we might detect a too-few args situation. -- (One can think of cases when the opposite order would give -- a better error message.) + -- [March 2003: I'm experimenting with putting this first. Here's an + -- example where it actually makes a real difference + -- class C t a b | t a -> b + -- instance C Char a Bool + -- + -- data P t a = forall b. (C t a b) => MkP b + -- data Q t = MkQ (forall a. P t a) + + -- f1, f2 :: Q Char; + -- f1 = MkQ (MkP True) + -- f2 = MkQ (MkP True :: forall a. P Char a) + -- + -- With the change, f1 will type-check, because the 'Char' info from + -- the signature is propagated into MkQ's argument. With the check + -- in the other order, the extra signature in f2 is reqd.] + addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) - (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn -> + (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn -> + + -- Now typecheck the args + mappM (tcArg fun) + (zip3 args expected_arg_tys [1..]) `thenM` \ args' -> returnM (co_fn <$> foldl HsApp fun' args') -- If an error happens we try to figure out whether the -- function has been given too many or too few arguments, --- and say so -checkArgsCtxt fun args expected_res_ty actual_res_ty tidy_env +-- and say so. +-- The ~(Check...) is because in the Infer case the tcSubExp +-- definitely won't fail, so we can be certain we're in the Check branch +checkArgsCtxt fun args ~(Check expected_res_ty) actual_res_ty tidy_env = zonkTcType expected_res_ty `thenM` \ exp_ty' -> zonkTcType actual_res_ty `thenM` \ act_ty' -> let @@ -704,7 +669,7 @@ checkArgsCtxt fun args expected_res_ty actual_res_ty tidy_env returnM (env2, message) -split_fun_ty :: TcType -- The type of the function +split_fun_ty :: TcRhoType -- The type of the function -> Int -- Number of arguments -> TcM ([TcType], -- Function argument types TcType) -- Function result types @@ -726,7 +691,7 @@ tcArg :: RenamedHsExpr -- The function (for error messages) tcArg the_fun (arg, expected_arg_ty, arg_no) = addErrCtxt (funAppCtxt the_fun arg arg_no) $ - tcExpr arg expected_arg_ty + tcCheckSigma arg expected_arg_ty \end{code} @@ -759,69 +724,70 @@ This gets a bit less sharing, but b) perhaps fewer separated lambdas \begin{code} -tcId :: Name -> TcM (TcExpr, TcType) +tcId :: Name -> TcM (TcExpr, TcRhoType) tcId name -- Look up the Id and instantiate its type = -- First check whether it's a DataCon -- Reason: we must not forget to chuck in the -- constraints from their "silly context" - tcLookupGlobal_maybe name `thenM` \ maybe_thing -> - case maybe_thing of { - Just (ADataCon data_con) -> inst_data_con data_con ; - other -> - - -- OK, so now look for ordinary Ids - tcLookupIdLvl name `thenM` \ (id, bind_lvl) -> + tcLookup name `thenM` \ thing -> + case thing of { + AGlobal (ADataCon data_con) -> inst_data_con data_con + ; AGlobal (AnId id) -> loop (HsVar id) (idType id) + -- A global cannot possibly be ill-staged + -- nor does it need the 'lifting' treatment + + ; ATcId id th_level proc_level -> tc_local_id id th_level proc_level + ; other -> pprPanic "tcId" (ppr name $$ ppr thing) + } + where #ifndef GHCI - loop (HsVar id) (idType id) -- Non-TH case + tc_local_id id th_bind_lvl proc_lvl -- Non-TH case + = checkProcLevel id proc_lvl `thenM_` + loop (HsVar id) (idType id) + +#else /* GHCI and TH is on */ + tc_local_id id th_bind_lvl proc_lvl -- TH case + = checkProcLevel id proc_lvl `thenM_` -#else /* GHCI is on */ -- Check for cross-stage lifting - getStage `thenM` \ use_stage -> - case use_stage of - Brack use_lvl ps_var lie_var - | use_lvl > bind_lvl && not (isExternalName name) - -> -- E.g. \x -> [| h x |] + getStage `thenM` \ use_stage -> + case use_stage of + Brack use_lvl ps_var lie_var + | use_lvl > th_bind_lvl + -> -- E.g. \x -> [| h x |] -- We must behave as if the reference to x was + -- h $(lift x) -- We use 'x' itself as the splice proxy, used by -- the desugarer to stitch it all back together. -- If 'x' occurs many times we may get many identical -- bindings of the same splice proxy, but that doesn't -- matter, although it's a mite untidy. - -- - -- NB: During type-checking, isExernalName is true of - -- top level things, and false of nested bindings - -- Top-level things don't need lifting. - - let - id_ty = idType id - in - checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_` + let + id_ty = idType id + in + checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_` -- If x is polymorphic, its occurrence sites might -- have different instantiations, so we can't use plain -- 'x' as the splice proxy name. I don't know how to -- solve this, and it's probably unimportant, so I'm -- just going to flag an error for now - setLIEVar lie_var ( - newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift -> - -- Put the 'lift' constraint into the right LIE + setLIEVar lie_var ( + newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift -> + -- Put the 'lift' constraint into the right LIE - -- Update the pending splices - readMutVar ps_var `thenM` \ ps -> - writeMutVar ps_var ((name, HsApp (HsVar lift) (HsVar id)) : ps) `thenM_` - - returnM (HsVar id, id_ty)) + -- Update the pending splices + readMutVar ps_var `thenM` \ ps -> + writeMutVar ps_var ((name, HsApp (HsVar lift) (HsVar id)) : ps) `thenM_` + + returnM (HsVar id, id_ty)) - other -> - checkWellStaged (quotes (ppr id)) bind_lvl use_stage `thenM_` - loop (HsVar id) (idType id) -#endif - } - - where - orig = OccurrenceOf name + other -> + checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_` + loop (HsVar id) (idType id) +#endif /* GHCI */ loop (HsVar fun_id) fun_ty | want_method_inst fun_ty @@ -833,7 +799,7 @@ tcId name -- Look up the Id and instantiate its type loop fun fun_ty | isSigmaTy fun_ty = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) -> - loop (inst_fn fun) tau + loop (inst_fn <$> fun) tau | otherwise = returnM (fun, fun_ty) @@ -855,30 +821,18 @@ tcId name -- Look up the Id and instantiate its type -- We treat data constructors differently, because we have to generate -- constraints for their silly theta, which no longer appears in - -- the type of dataConWrapId. It's dual to TcPat.tcConstructor + -- the type of dataConWrapId (see note on "stupid context" in DataCon.lhs + -- It's dual to TcPat.tcConstructor inst_data_con data_con = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) -> extendLIEs ex_dicts `thenM_` returnM (mkHsDictApp (mkHsTyApp (HsVar (dataConWrapId data_con)) ty_args) (map instToId ex_dicts), mkFunTys arg_tys result_ty) -\end{code} - -Typecheck expression which in most cases will be an Id. -The expression can return a higher-ranked type, such as - (forall a. a->a) -> Int -so we must create a HoleTyVarTy to pass in as the expected tyvar. -\begin{code} -tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, TcType) -tcExpr_id (HsVar name) = tcId name -tcExpr_id expr = newHoleTyVarTy `thenM` \ id_ty -> - tcMonoExpr expr id_ty `thenM` \ expr' -> - readHoleResult id_ty `thenM` \ id_ty' -> - returnM (expr', id_ty') + orig = OccurrenceOf name \end{code} - %************************************************************************ %* * \subsection{Record bindings} @@ -929,7 +883,7 @@ tcRecordBinds tycon ty_args rbinds -- The caller of tcRecordBinds has already checked -- that all the fields come from the same type - tcExpr rhs field_ty `thenM` \ rhs' -> + tcCheckSigma rhs field_ty `thenM` \ rhs' -> returnM (sel_id, rhs') @@ -975,25 +929,22 @@ checkMissingFields data_con rbinds field_labels field_strs - field_strs = dropList ex_theta (dataConStrictMarks data_con) - -- The 'drop' is because dataConStrictMarks - -- includes the existential dictionaries - (_, _, _, ex_theta, _, _) = dataConSig data_con + field_strs = dataConStrictMarks data_con \end{code} %************************************************************************ %* * -\subsection{@tcMonoExprs@ typechecks a {\em list} of expressions} +\subsection{@tcCheckRhos@ typechecks a {\em list} of expressions} %* * %************************************************************************ \begin{code} -tcMonoExprs :: [RenamedHsExpr] -> [TcType] -> TcM [TcExpr] +tcCheckRhos :: [RenamedHsExpr] -> [TcType] -> TcM [TcExpr] -tcMonoExprs [] [] = returnM [] -tcMonoExprs (expr:exprs) (ty:tys) - = tcMonoExpr expr ty `thenM` \ expr' -> - tcMonoExprs exprs tys `thenM` \ exprs' -> +tcCheckRhos [] [] = returnM [] +tcCheckRhos (expr:exprs) (ty:tys) + = tcCheckRho expr ty `thenM` \ expr' -> + tcCheckRhos exprs tys `thenM` \ exprs' -> returnM (expr':exprs') \end{code} @@ -1007,16 +958,9 @@ tcMonoExprs (expr:exprs) (ty:tys) Overloaded literals. \begin{code} -tcLit :: HsLit -> TcType -> TcM TcExpr -tcLit (HsLitLit s _) res_ty - = tcLookupClass cCallableClassName `thenM` \ cCallableClass -> - newDicts (LitLitOrigin (unpackFS s)) - [mkClassPred cCallableClass [res_ty]] `thenM` \ dicts -> - extendLIEs dicts `thenM_` - returnM (HsLit (HsLitLit s res_ty)) - +tcLit :: HsLit -> Expected TcRhoType -> TcM TcExpr tcLit lit res_ty - = unifyTauTy res_ty (hsLitType lit) `thenM_` + = zapExpectedTo res_ty (hsLitType lit) `thenM_` returnM (HsLit lit) \end{code} @@ -1070,11 +1014,6 @@ appCtxt fun args where the_app = foldl HsApp fun args -- Used in error messages -lurkingRank2Err fun fun_ty - = hang (hsep [ptext SLIT("Illegal use of"), quotes (ppr fun)]) - 4 (vcat [ptext SLIT("It is applied to too few arguments"), - ptext SLIT("so that the result type has for-alls in it:") <+> ppr fun_ty]) - badFieldsUpd rbinds = hang (ptext SLIT("No constructor has all these fields:")) 4 (pprQuotedList (recBindFields rbinds)) @@ -1101,10 +1040,6 @@ missingFields con fields = ptext SLIT("Fields of") <+> quotes (ppr con) <+> ptext SLIT("not initialised:") <+> pprWithCommas ppr fields -polySpliceErr :: Id -> SDoc -polySpliceErr id - = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id) - wrongArgsCtxt too_many_or_few fun args = hang (ptext SLIT("Probable cause:") <+> quotes (ppr fun) <+> ptext SLIT("is applied to") <+> text too_many_or_few @@ -1112,4 +1047,10 @@ wrongArgsCtxt too_many_or_few fun args 4 (parens (ppr the_app)) where the_app = foldl HsApp fun args -- Used in error messages + +#ifdef GHCI +polySpliceErr :: Id -> SDoc +polySpliceErr id + = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id) +#endif \end{code}