X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=a67d30e9d3fc73107e13c01b96486f419b47b28d;hb=6c3c61e070a52231887db1cdc3a35bec021dcf42;hp=72587b71d16968b67d73ac45356d106b58e689c1;hpb=1c3601593186639f1086bc402582ff56fd3fe9f8;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 72587b7..a67d30e 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -4,74 +4,69 @@ \section[TcExpr]{Typecheck an expression} \begin{code} -module TcExpr ( tcApp, tcExpr, tcPolyExpr, tcId ) where +module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where #include "HsVersions.h" -import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), - MonoBinds(..), StmtCtxt(..), - mkMonoBind, nullMonoBinds - ) -import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds ) -import TcHsSyn ( TcExpr, TcRecordBinds, mkHsTyApp, mkHsLet ) - -import TcMonad -import BasicTypes ( RecFlag(..) ) - -import Inst ( InstOrigin(..), - LIE, emptyLIE, unitLIE, plusLIE, plusLIEs, - newOverloadedLit, newMethod, newIPDict, - instOverloadedFun, newDicts, newClassDicts, - getIPsOfLIE, instToId, ipToId - ) +#ifdef GHCI /* Only if bootstrapped */ +import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket ) +import Id ( Id ) +import Name ( isExternalName ) +import TcType ( isTauTy ) +import TcEnv ( checkWellStaged ) +import HsSyn ( nlHsApp ) +import qualified DsMeta +#endif + +import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields, + HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar ) +import TcHsSyn ( hsLitType, (<$>) ) +import TcRnMonad +import TcUnify ( Expected(..), tcInfer, zapExpectedType, zapExpectedTo, tcSubExp, tcGen, + unifyFunTys, zapToListTy, zapToTyConApp ) +import BasicTypes ( isMarkedStrict ) +import Inst ( newOverloadedLit, newMethodFromName, newIPDict, + newDicts, newMethodWithGivenTy, tcInstStupidTheta, tcInstCall ) import TcBinds ( tcBindsAndThen ) -import TcEnv ( tcInstId, - tcLookupValue, tcLookupClass, tcLookupGlobalId, - tcLookupTyCon, tcLookupDataCon, - tcExtendGlobalTyVars, tcLookupValueMaybe, - ) -import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts ) -import TcMonoType ( tcHsSigType, checkSigTyVars, sigCtxt ) -import TcPat ( badFieldCon, simpleHsLitTy ) -import TcSimplify ( tcSimplifyAndCheck, partitionPredsOfLIE ) -import TcImprove ( tcImprove ) -import TcType ( TcType, TcTauType, - tcInstTyVars, - tcInstTcType, tcSplitRhoTy, - newTyVarTy, newTyVarTys, zonkTcType ) - -import FieldLabel ( fieldLabelName, fieldLabelType, fieldLabelTyCon ) -import Id ( idType, recordSelectorFieldLabel, isRecordSelector, mkVanillaId ) -import DataCon ( dataConFieldLabels, dataConSig, - dataConStrictMarks, StrictnessMark(..) +import TcEnv ( tcLookup, tcLookupId, checkProcLevel, + tcLookupDataCon, tcLookupGlobalId ) -import Name ( Name, getName ) -import Type ( mkFunTy, mkAppTy, mkTyVarTys, ipName_maybe, - splitFunTy_maybe, splitFunTys, isNotUsgTy, - mkTyConApp, splitSigmaTy, - splitRhoTy, - isTauTy, tyVarsOfType, tyVarsOfTypes, - isSigmaTy, splitAlgTyConApp, splitAlgTyConApp_maybe, - boxedTypeKind, openTypeKind, mkArrowKind, - tidyOpenType +import TcArrows ( tcProc ) +import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) ) +import TcHsType ( tcHsSigType, UserTypeCtxt(..) ) +import TcPat ( badFieldCon, refineTyVars ) +import TcMType ( tcInstTyVars, tcInstType, newTyFlexiVarTy, zonkTcType ) +import TcType ( Type, TcTyVar, TcType, TcSigmaType, TcRhoType, + tcSplitFunTys, tcSplitTyConApp, mkTyVarTys, + isSigmaTy, mkFunTy, mkTyConApp, tyVarsOfTypes, isLinearPred, + tcSplitSigmaTy, tidyOpenType ) -import TyCon ( TyCon, tyConTyVars ) -import Subst ( mkTopTyVarSubst, substClasses, substTy ) -import UsageSPUtils ( unannotTy ) -import VarSet ( elemVarSet, mkVarSet ) -import TysWiredIn ( boolTy ) -import TcUnify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy ) -import PrelNames ( cCallableClassKey, cReturnableClassKey, - enumFromClassOpKey, enumFromThenClassOpKey, - enumFromToClassOpKey, enumFromThenToClassOpKey, - thenMClassOpKey, failMClassOpKey, returnMClassOpKey, ioTyConKey +import Kind ( openTypeKind, liftedTypeKind, argTypeKind ) + +import Id ( idType, recordSelectorFieldLabel, isRecordSelector ) +import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId ) +import Name ( Name ) +import TyCon ( TyCon, FieldLabel, tyConTyVars, tyConStupidTheta, + tyConDataCons, tyConFields ) +import Type ( zipTopTvSubst, substTheta, substTy ) +import Var ( tyVarKind ) +import VarSet ( emptyVarSet, elemVarSet ) +import TysWiredIn ( boolTy, parrTyCon, tupleTyCon ) +import PrelNames ( enumFromName, enumFromThenName, + enumFromToName, enumFromThenToName, + enumFromToPName, enumFromThenToPName ) -import Outputable -import Maybes ( maybeToBool, mapMaybe ) import ListSetOps ( minusList ) +import CmdLineOpts +import HscTypes ( TyThing(..) ) +import SrcLoc ( Located(..), unLoc, getLoc ) import Util -import CmdLineOpts ( opt_WarnMissingFields ) +import Outputable +import FastString +#ifdef DEBUG +import TyCon ( isAlgTyCon ) +#endif \end{code} %************************************************************************ @@ -81,118 +76,102 @@ import CmdLineOpts ( opt_WarnMissingFields ) %************************************************************************ \begin{code} -tcExpr :: RenamedHsExpr -- Expession to type check - -> TcType -- Expected type (could be a polytpye) - -> TcM (TcExpr, LIE) +-- tcCheckSigma does type *checking*; it's passed the expected type of the result +tcCheckSigma :: LHsExpr Name -- Expession to type check + -> TcSigmaType -- Expected type (could be a polytpye) + -> TcM (LHsExpr TcId) -- Generalised expr with expected type + +tcCheckSigma expr expected_ty + = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_` + tc_expr' expr expected_ty + +tc_expr' expr sigma_ty + | isSigmaTy sigma_ty + = tcGen sigma_ty emptyVarSet ( + \ rho_ty -> tcCheckRho expr rho_ty + ) `thenM` \ (gen_fn, expr') -> + returnM (L (getLoc expr') (gen_fn <$> unLoc 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. -tcExpr expr ty | isSigmaTy ty = -- Polymorphic case - tcPolyExpr expr ty `thenTc` \ (expr', lie, _, _, _) -> - returnTc (expr', lie) +\begin{code} +tcCheckRho :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId) +tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty) - | otherwise = -- Monomorphic case - tcMonoExpr expr ty +tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType) +tcInferRho (L loc (HsVar name)) = setSrcSpan loc $ do + { (e,_,ty) <- tcId name; return (L loc e, ty)} +tcInferRho expr = tcInfer (tcMonoExpr expr) \end{code} + %************************************************************************ %* * -\subsection{@tcPolyExpr@ typchecks an application} +\subsection{The TAUT rules for variables}TcExpr %* * %************************************************************************ \begin{code} --- tcPolyExpr is like tcMonoExpr, except that the expected type --- can be a polymorphic one. -tcPolyExpr :: RenamedHsExpr - -> TcType -- Expected type - -> TcM (TcExpr, LIE, -- Generalised expr with expected type, and LIE - TcExpr, TcTauType, LIE) -- Same thing, but instantiated; tau-type returned - -tcPolyExpr arg expected_arg_ty - = -- Ha! The argument type of the function is a for-all type, - -- An example of rank-2 polymorphism. - - -- To ensure that the forall'd type variables don't get unified with each - -- other or any other types, we make fresh copy of the alleged type - tcInstTcType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_rho) -> - let - (sig_theta, sig_tau) = splitRhoTy sig_rho - free_tyvars = tyVarsOfType expected_arg_ty - in - -- Type-check the arg and unify with expected type - tcMonoExpr arg sig_tau `thenTc` \ (arg', lie_arg) -> - - -- Check that the sig_tyvars havn't been constrained - -- The interesting bit here is that we must include the free variables - -- of the expected arg ty. Here's an example: - -- runST (newVar True) - -- Here, if we don't make a check, we'll get a type (ST s (MutVar s Bool)) - -- for (newVar True), with s fresh. Then we unify with the runST's arg type - -- forall s'. ST s' a. That unifies s' with s, and a with MutVar s Bool. - -- So now s' isn't unconstrained because it's linked to a. - -- Conclusion: include the free vars of the expected arg type in the - -- list of "free vars" for the signature check. - - tcExtendGlobalTyVars free_tyvars $ - tcAddErrCtxtM (sigCtxt sig_msg sig_tyvars sig_theta sig_tau) $ - - checkSigTyVars sig_tyvars free_tyvars `thenTc` \ zonked_sig_tyvars -> - - newDicts SignatureOrigin sig_theta `thenNF_Tc` \ (sig_dicts, dict_ids) -> - tcImprove (sig_dicts `plusLIE` lie_arg) `thenTc_` - -- ToDo: better origin - tcSimplifyAndCheck - (text "the type signature of an expression") - (mkVarSet zonked_sig_tyvars) - sig_dicts lie_arg `thenTc` \ (free_insts, inst_binds) -> - - let - -- This HsLet binds any Insts which came out of the simplification. - -- It's a bit out of place here, but using AbsBind involves inventing - -- a couple of new names which seems worse. - generalised_arg = TyLam zonked_sig_tyvars $ - DictLam dict_ids $ - mkHsLet inst_binds $ - arg' - in - returnTc ( generalised_arg, free_insts, - arg', sig_tau, lie_arg ) - where - sig_msg = ptext SLIT("When checking an expression type signature") +tcMonoExpr :: LHsExpr Name -- Expession to type check + -> Expected TcRhoType -- Expected type (could be a type variable) + -- Definitely no foralls at the top + -- Can be a 'hole'. + -> TcM (LHsExpr TcId) + +tcMonoExpr (L loc expr) res_ty + = setSrcSpan loc (do { expr' <- tc_expr expr res_ty + ; return (L loc expr') }) + +tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId) +tc_expr (HsVar name) res_ty + = do { (expr', _, id_ty) <- tcId name + ; co_fn <- tcSubExp res_ty id_ty + ; returnM (co_fn <$> expr') } + +tc_expr (HsIPVar ip) res_ty + = -- Implicit parameters must have a *tau-type* not a + -- type scheme. We enforce this by creating a fresh + -- type variable as its type. (Because res_ty may not + -- be a tau-type.) + newTyFlexiVarTy argTypeKind `thenM` \ ip_ty -> + -- argTypeKind: it can't be an unboxed tuple + newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) -> + extendLIE inst `thenM_` + tcSubExp res_ty ip_ty `thenM` \ co_fn -> + returnM (co_fn <$> HsIPVar ip') \end{code} + %************************************************************************ %* * -\subsection{The TAUT rules for variables} +\subsection{Expressions type signatures} %* * %************************************************************************ \begin{code} -tcMonoExpr :: RenamedHsExpr -- Expession to type check - -> TcTauType -- Expected type (could be a type variable) - -> TcM (TcExpr, LIE) - -tcMonoExpr (HsVar name) res_ty - = tcId name `thenNF_Tc` \ (expr', lie, id_ty) -> - unifyTauTy res_ty id_ty `thenTc_` - - -- Check that the result type doesn't have any nested for-alls. - -- For example, a "build" on its own is no good; it must be - -- applied to something. - checkTc (isTauTy id_ty) - (lurkingRank2Err name id_ty) `thenTc_` - - returnTc (expr', lie) +tc_expr in_expr@(ExprWithTySig expr poly_ty) res_ty + = addErrCtxt (exprCtxt 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 <$> ExprWithTySigOut expr' poly_ty) + +tc_expr (HsType ty) res_ty + = failWithTc (text "Can't handle type argument:" <+> ppr ty) + -- This is the syntax for type applications that I was planning + -- but there are difficulties (e.g. what order for type args) + -- so it's not enabled yet. + -- Can't eliminate it altogether from the parser, because the + -- same parser parses *patterns*. \end{code} -\begin{code} -tcMonoExpr (HsIPVar name) res_ty - -- ZZ What's the `id' used for here... - = let id = mkVanillaId name res_ty in - tcGetInstLoc (OccurrenceOf id) `thenNF_Tc` \ loc -> - newIPDict name res_ty loc `thenNF_Tc` \ ip -> - returnNF_Tc (HsIPVar (instToId ip), unitLIE ip) -\end{code} %************************************************************************ %* * @@ -201,28 +180,33 @@ tcMonoExpr (HsIPVar name) 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 (HsPar expr) res_ty = tcMonoExpr expr res_ty - -tcMonoExpr (NegApp expr neg) res_ty - = tcMonoExpr (HsApp (HsVar neg) expr) res_ty - -tcMonoExpr (HsLam match) res_ty - = tcMatchLambda match res_ty `thenTc` \ (match',lie) -> - returnTc (HsLam match', lie) - -tcMonoExpr (HsApp e1 e2) res_ty = accum e1 [e2] - where - accum (HsApp e1 e2) args = accum e1 (e2:args) - accum fun args - = tcApp fun args res_ty `thenTc` \ (fun', args', lie) -> - returnTc (foldl HsApp fun' args', lie) - --- equivalent to (op e1) e2: -tcMonoExpr (OpApp arg1 op fix arg2) res_ty - = tcApp op [arg1,arg2] res_ty `thenTc` \ (op', [arg1', arg2'], lie) -> - returnTc (OpApp arg1' op' fix arg2', lie) +tc_expr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> + returnM (HsPar expr') +tc_expr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> + returnM (HsSCC lbl expr') +tc_expr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation + returnM (HsCoreAnn lbl expr') + +tc_expr (HsLit lit) res_ty = tcLit lit res_ty + +tc_expr (HsOverLit lit) res_ty + = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' -> + -- Overloaded literals must have liftedTypeKind, because + -- we're instantiating an overloaded function here, + -- whereas res_ty might be openTypeKind. This was a bug in 6.2.2 + newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr -> + returnM (unLoc lit_expr) -- ToDo: nasty unLoc + +tc_expr (NegApp expr neg_name) res_ty + = tc_expr (HsApp (nlHsVar neg_name) expr) res_ty + -- ToDo: use tcSyntaxName + +tc_expr (HsLam match) res_ty + = tcMatchLambda match res_ty `thenM` \ match' -> + returnM (HsLam match') + +tc_expr (HsApp e1 e2) res_ty + = tcApp e1 [e2] res_ty \end{code} Note that the operators in sections are expected to be binary, and @@ -236,192 +220,153 @@ a type error will occur if they aren't. -- or just -- op e -tcMonoExpr in_expr@(SectionL arg op) res_ty - = tcApp op [arg] res_ty `thenTc` \ (op', [arg'], lie) -> - - -- Check that res_ty is a function type - -- Without this check we barf in the desugarer on - -- f op = (3 `op`) - -- because it tries to desugar to - -- f op = \r -> 3 op r - -- so (3 `op`) had better be a function! - tcAddErrCtxt (sectionLAppCtxt in_expr) $ - unifyFunTy res_ty `thenTc_` - - returnTc (SectionL arg' op', lie) +tc_expr in_expr@(SectionL arg1 op) res_ty + = tcInferRho op `thenM` \ (op', op_ty) -> + unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> + tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' -> + addErrCtxt (exprCtxt in_expr) $ + tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenM` \ co_fn -> + returnM (co_fn <$> SectionL arg1' op') -- Right sections, equivalent to \ x -> x op expr, or -- \ x -> op x expr -tcMonoExpr in_expr@(SectionR op expr) res_ty - = tcExpr_id op `thenTc` \ (op', lie1, op_ty) -> - tcAddErrCtxt (sectionRAppCtxt in_expr) $ - split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) -> - tcMonoExpr expr arg2_ty `thenTc` \ (expr',lie2) -> - unifyTauTy res_ty (mkFunTy arg1_ty op_res_ty) `thenTc_` - returnTc (SectionR op' expr', lie1 `plusLIE` lie2) -\end{code} - -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 (HsCCall lbl args may_gc is_asm ignored_fake_result_ty) res_ty - = -- Get the callable and returnable classes. - tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass -> - tcLookupClass cReturnableClassName `thenNF_Tc` \ cReturnableClass -> - tcLookupTyCon ioTyConName `thenNF_Tc` \ ioTyCon -> - let - new_arg_dict (arg, arg_ty) - = newClassDicts (CCallOrigin (_UNPK_ lbl) (Just arg)) - [(cCallableClass, [arg_ty])] `thenNF_Tc` \ (arg_dicts, _) -> - returnNF_Tc arg_dicts -- Actually a singleton bag - - result_origin = CCallOrigin (_UNPK_ lbl) Nothing {- Not an arg -} - in +tc_expr in_expr@(SectionR op arg2) res_ty + = tcInferRho op `thenM` \ (op', op_ty) -> + unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> + tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' -> + addErrCtxt (exprCtxt in_expr) $ + tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn -> + returnM (co_fn <$> SectionR op' arg2') - -- Arguments - let n_args = length args - tv_idxs | n_args == 0 = [] - | otherwise = [1..n_args] - in - newTyVarTys (length tv_idxs) openTypeKind `thenNF_Tc` \ arg_tys -> - tcMonoExprs args arg_tys `thenTc` \ (args', args_lie) -> +-- equivalent to (op e1) e2: - -- The argument types can be unboxed or boxed; the result - -- type must, however, be boxed since it's an argument to the IO - -- type constructor. - newTyVarTy boxedTypeKind `thenNF_Tc` \ result_ty -> - let - io_result_ty = mkTyConApp ioTyCon [result_ty] - in - unifyTauTy res_ty io_result_ty `thenTc_` - - -- Construct the extra insts, which encode the - -- constraints on the argument and result types. - mapNF_Tc new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s -> - newClassDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) -> - returnTc (HsCCall lbl args' may_gc is_asm io_result_ty, - foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie) +tc_expr in_expr@(OpApp arg1 op fix arg2) res_ty + = tcInferRho op `thenM` \ (op', op_ty) -> + unifyFunTys 2 op_ty {- 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' -> + addErrCtxt (exprCtxt in_expr) $ + tcSubExp res_ty op_res_ty `thenM` \ co_fn -> + returnM (OpApp arg1' op' fix arg2') \end{code} \begin{code} -tcMonoExpr (HsSCC lbl expr) res_ty - = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) -> - returnTc (HsSCC lbl expr', lie) - -tcMonoExpr (HsLet binds expr) res_ty +tc_expr (HsLet binds (L loc expr)) res_ty = tcBindsAndThen - combiner + glue binds -- Bindings to check - tc_expr `thenTc` \ (expr', lie) -> - returnTc (expr', lie) + (setSrcSpan loc $ tc_expr expr res_ty) where - tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) -> - returnTc (expr', lie) - combiner is_rec bind expr = HsLet (mkMonoBind bind [] is_rec) expr + glue bind expr = HsLet [bind] (L loc expr) -tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (caseCtxt in_expr) $ - - -- Typecheck the case alternatives first. +tc_expr in_expr@(HsCase scrut matches) exp_ty + = -- We used to typecheck the case alternatives first. -- The case patterns tend to give good type info to use -- when typechecking the scrutinee. For example -- 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 `thenTc` \ (scrut_ty, matches', lie2) -> - - tcAddErrCtxt (caseScrutCtxt scrut) ( - tcMonoExpr scrut scrut_ty - ) `thenTc` \ (scrut',lie1) -> - - returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2) - -tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (predCtxt pred) ( - tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) -> - - tcMonoExpr b1 res_ty `thenTc` \ (b1',lie2) -> - tcMonoExpr b2 res_ty `thenTc` \ (b2',lie3) -> - returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3)) -\end{code} + -- But now, in the GADT world, we need to typecheck the scrutinee + -- first, to get type info that may be refined in the case alternatives + addErrCtxt (caseScrutCtxt scrut) + (tcInferRho scrut) `thenM` \ (scrut', scrut_ty) -> + + addErrCtxt (caseCtxt in_expr) $ + tcMatchesCase match_ctxt scrut_ty matches exp_ty `thenM` \ matches' -> + returnM (HsCase scrut' matches') + where + match_ctxt = MC { mc_what = CaseAlt, + mc_body = tcMonoExpr } + +tc_expr (HsIf pred b1 b2) res_ty + = addErrCtxt (predCtxt pred) ( + tcCheckRho pred boolTy ) `thenM` \ pred' -> + + zapExpectedType res_ty openTypeKind `thenM` \ res_ty' -> + -- C.f. the call to zapToType in TcMatches.tcMatches + + tcCheckRho b1 res_ty' `thenM` \ b1' -> + tcCheckRho b2 res_ty' `thenM` \ b2' -> + returnM (HsIf pred' b1' b2') + +tc_expr (HsDo do_or_lc stmts method_names _) res_ty + = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' -> + -- All comprehensions yield a monotype of kind * + tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') -> + returnM (HsDo do_or_lc stmts' methods' res_ty') + +tc_expr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list + = 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) $ + tcCheckRho expr elt_ty -\begin{code} -tcMonoExpr expr@(HsDo do_or_lc stmts src_loc) res_ty - = tcDoStmts do_or_lc stmts src_loc res_ty +tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty + = do { [elt_ty] <- zapToTyConApp parrTyCon res_ty + ; exprs' <- mappM (tc_elt elt_ty) exprs + ; return (ExplicitPArr elt_ty exprs') } + where + tc_elt elt_ty expr + = addErrCtxt (parrCtxt expr) (tcCheckRho expr elt_ty) + +tc_expr (ExplicitTuple exprs boxity) res_ty + = do { arg_tys <- zapToTyConApp (tupleTyCon boxity (length exprs)) res_ty + ; exprs' <- tcCheckRhos exprs arg_tys + ; return (ExplicitTuple exprs' boxity) } + +tc_expr (HsProc pat cmd) res_ty + = tcProc pat cmd res_ty `thenM` \ (pat', cmd') -> + returnM (HsProc pat' cmd') + +tc_expr e@(HsArrApp _ _ _ _ _) _ + = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e), + ptext SLIT("was found where an expression was expected")]) + +tc_expr e@(HsArrForm _ _ _) _ + = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e), + ptext SLIT("was found where an expression was expected")]) \end{code} +%************************************************************************ +%* * + Record construction and update +%* * +%************************************************************************ + \begin{code} -tcMonoExpr in_expr@(ExplicitList exprs) res_ty -- Non-empty list - = unifyListTy res_ty `thenTc` \ elt_ty -> - mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) -> - returnTc (ExplicitListOut elt_ty exprs', plusLIEs lies) - where - tc_elt elt_ty expr - = tcAddErrCtxt (listCtxt expr) $ - tcMonoExpr expr elt_ty - -tcMonoExpr (ExplicitTuple exprs boxity) res_ty - = unifyTupleTy boxity (length exprs) res_ty `thenTc` \ arg_tys -> - mapAndUnzipTc (\ (expr, arg_ty) -> tcMonoExpr expr arg_ty) - (exprs `zip` arg_tys) -- we know they're of equal length. - `thenTc` \ (exprs', lies) -> - returnTc (ExplicitTuple exprs' boxity, plusLIEs lies) - -tcMonoExpr expr@(RecordCon con_name rbinds) res_ty - = tcAddErrCtxt (recordConCtxt expr) $ - tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) -> +tc_expr expr@(RecordCon con@(L loc con_name) rbinds) res_ty + = addErrCtxt (recordConCtxt expr) $ + addLocM tcId con `thenM` \ (con_expr, _, con_tau) -> let - (_, record_ty) = splitFunTys con_tau - (tycon, ty_args, _) = splitAlgTyConApp record_ty + (_, record_ty) = tcSplitFunTys con_tau + (tycon, ty_args) = tcSplitTyConApp record_ty in - ASSERT( maybeToBool (splitAlgTyConApp_maybe record_ty ) ) - unifyTauTy res_ty record_ty `thenTc_` + ASSERT( isAlgTyCon tycon ) + 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 `thenTc` \ (data_con, _, _) -> + tcLookupDataCon con_name `thenM` \ data_con -> let bad_fields = badFields rbinds data_con in - if not (null bad_fields) then - mapNF_Tc (addErrTc . badFieldCon con_name) bad_fields `thenNF_Tc_` - failTc -- Fail now, because tcRecordBinds will crash on a bad field + if notNull bad_fields then + mappM (addErrTc . badFieldCon data_con) bad_fields `thenM_` + failM -- Fail now, because tcRecordBinds will crash on a bad field else -- Typecheck the record bindings - tcRecordBinds tycon ty_args rbinds `thenTc` \ (rbinds', rbinds_lie) -> + tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' -> - let - missing_s_fields = missingStrictFields rbinds data_con - in - checkTcM (null missing_s_fields) - (mapNF_Tc (addErrTc . missingStrictFieldCon con_name) missing_s_fields `thenNF_Tc_` - returnNF_Tc ()) `thenNF_Tc_` - let - missing_fields = missingFields rbinds data_con - in - checkTcM (not (opt_WarnMissingFields && not (null missing_fields))) - (mapNF_Tc ((warnTc True) . missingFieldCon con_name) missing_fields `thenNF_Tc_` - returnNF_Tc ()) `thenNF_Tc_` + -- Check for missing fields + checkMissingFields data_con rbinds `thenM_` - returnTc (RecordConOut data_con con_expr rbinds', con_lie `plusLIE` rbinds_lie) + returnM (RecordConOut data_con (L loc con_expr) rbinds') -- The main complication with RecordUpd is that we need to explicitly -- handle the *non-updated* fields. Consider: @@ -449,44 +394,42 @@ tcMonoExpr expr@(RecordCon con_name rbinds) res_ty -- -- All this is done in STEP 4 below. -tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty - = tcAddErrCtxt (recordUpdCtxt expr) $ +tc_expr expr@(RecordUpd record_expr rbinds) res_ty + = addErrCtxt (recordUpdCtxt expr) $ -- STEP 0 -- Check that the field names are really field names - ASSERT( not (null rbinds) ) + ASSERT( notNull rbinds ) let - field_names = [field_name | (field_name, _, _) <- rbinds] + field_names = map fst rbinds in - mapNF_Tc tcLookupGlobal_maybe field_names `thenNF_Tc` \ maybe_sel_ids -> + mappM (tcLookupGlobalId.unLoc) 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, - case maybe_sel_id of - Just (AnId sel_id) -> not (isRecordSelector sel_id) - other -> True + bad_guys = [ setSrcSpan loc $ addErrTc (notSelector field_name) + | (L loc field_name, sel_id) <- field_names `zip` sel_ids, + not (isRecordSelector sel_id) -- Excludes class ops ] in - checkTcM (null bad_guys) (listNF_Tc bad_guys `thenNF_Tc_` failTc) `thenTc_` + checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_` -- STEP 1 -- Figure out the tycon and data cons from the first field name let - (Just sel_id : _) = maybe_sel_ids - (_, _, tau) = ASSERT( isNotUsgTy (idType sel_id) ) - splitSigmaTy (idType sel_id) -- Selectors can be overloaded - -- when the data type has a context - Just (data_ty, _) = splitFunTy_maybe tau -- Must succeed since sel_id is a selector - (tycon, _, data_cons) = splitAlgTyConApp data_ty - (con_tyvars, _, _, _, _, _) = dataConSig (head data_cons) + -- It's OK to use the non-tc splitters here (for a selector) + sel_id : _ = sel_ids + (tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if + data_cons = tyConDataCons tycon -- it's not a field label + tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars in - tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) -> + tcInstTyVars tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) -> -- STEP 2 -- Check that at least one constructor has all the named fields -- i.e. has an empty set of bad fields returned by badFields checkTc (any (null . badFields rbinds) data_cons) - (badFieldsUpd rbinds) `thenTc_` + (badFieldsUpd rbinds) `thenM_` -- STEP 3 -- Typecheck the update bindings. @@ -495,8 +438,8 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty let result_record_ty = mkTyConApp tycon result_inst_tys in - unifyTauTy res_ty result_record_ty `thenTc_` - tcRecordBinds tycon result_inst_tys rbinds `thenTc` \ (rbinds', rbinds_lie) -> + zapExpectedTo res_ty result_record_ty `thenM_` + tcRecordBinds tycon result_inst_tys rbinds `thenM` \ rbinds' -> -- STEP 4 -- Use the un-updated fields to find a vector of booleans saying @@ -505,7 +448,7 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty -- WARNING: this code assumes that all data_cons in a common tycon -- have FieldLabels abstracted over the same tyvars. let - upd_field_lbls = [recordSelectorFieldLabel sel_id | (sel_id, _, _) <- rbinds'] + upd_field_lbls = recBindFields rbinds con_field_lbls_s = map dataConFieldLabels data_cons -- A constructor is only relevant to this process if @@ -514,192 +457,146 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls - common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls) + common_tyvars = tyVarsOfTypes [ty | (fld,ty,_) <- tyConFields tycon, + fld `elem` non_upd_field_lbls] + is_common_tv tv = tv `elemVarSet` common_tyvars - mk_inst_ty (tyvar, result_inst_ty) - | tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type - | otherwise = newTyVarTy boxedTypeKind -- Fresh type + mk_inst_ty tv result_inst_ty + | is_common_tv tv = returnM result_inst_ty -- Same as result type + | otherwise = newTyFlexiVarTy (tyVarKind tv) -- Fresh type, of correct kind in - mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys -> + zipWithM mk_inst_ty tycon_tyvars result_inst_tys `thenM` \ inst_tys -> -- STEP 5 -- Typecheck the expression to be updated let record_ty = mkTyConApp tycon inst_tys in - tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) -> + tcCheckRho record_expr record_ty `thenM` \ record_expr' -> -- STEP 6 -- Figure out the LIE we need. We have to generate some -- dictionaries for the data type context, since we are going to - -- do some construction. + -- do pattern matching over the data cons. -- - -- What dictionaries do we need? For the moment we assume that all - -- data constructors have the same context, and grab it from the first - -- constructor. If they have varying contexts then we'd have to - -- union the ones that could participate in the update. + -- What dictionaries do we need? + -- We just take the context of the type constructor let - (tyvars, theta, _, _, _, _) = dataConSig (head data_cons) - inst_env = mkTopTyVarSubst tyvars result_inst_tys - theta' = substClasses inst_env theta + theta' = substTheta inst_env (tyConStupidTheta tycon) in - newClassDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) -> + newDicts RecordUpdOrigin theta' `thenM` \ dicts -> + extendLIEs dicts `thenM_` -- Phew! - returnTc (RecordUpdOut record_expr' result_record_ty dicts rbinds', - con_lie `plusLIE` record_lie `plusLIE` rbinds_lie) - -tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty - = unifyListTy res_ty `thenTc` \ elt_ty -> - tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) -> - - tcLookupGlobalId enumFromClassOpName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - sel_id [elt_ty] `thenNF_Tc` \ (lie2, enum_from_id) -> - - returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'), - lie1 `plusLIE` lie2) - -tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty - = tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenTc` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> - tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> - tcLookupGlobalId enumFromThenClassOpName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ (lie3, enum_from_then_id) -> - - returnTc (ArithSeqOut (HsVar enum_from_then_id) - (FromThen expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` lie3) - -tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty - = tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenTc` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> - tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> - tcLookupGlobalId enumFromToClassOpName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ (lie3, enum_from_to_id) -> - - returnTc (ArithSeqOut (HsVar enum_from_to_id) - (FromTo expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` lie3) - -tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty - = tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenTc` \ elt_ty -> - tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> - tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> - tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) -> - tcLookupGlobalId enumFromThenToClassOpName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ (lie4, eft_id) -> - - returnTc (ArithSeqOut (HsVar eft_id) - (FromThenTo expr1' expr2' expr3'), - lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4) + returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds') \end{code} + %************************************************************************ %* * -\subsection{Expressions type signatures} + Arithmetic sequences e.g. [a,b..] + and their parallel-array counterparts e.g. [: a,b.. :] + %* * %************************************************************************ \begin{code} -tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty - = tcSetErrCtxt (exprSigCtxt in_expr) $ - tcHsSigType poly_ty `thenTc` \ sig_tc_ty -> - - if not (isSigmaTy sig_tc_ty) then - -- Easy case - unifyTauTy sig_tc_ty res_ty `thenTc_` - tcMonoExpr expr sig_tc_ty - - else -- Signature is polymorphic - tcPolyExpr expr sig_tc_ty `thenTc` \ (_, _, expr, expr_ty, lie) -> - - -- Now match the signature type with res_ty. - -- We must not do this earlier, because res_ty might well - -- mention variables free in the environment, and we'd get - -- bogus complaints about not being able to for-all the - -- sig_tyvars - unifyTauTy res_ty expr_ty `thenTc_` - - -- If everything is ok, return the stuff unchanged, except for - -- the effect of any substutions etc. We simply discard the - -- result of the tcSimplifyAndCheck (inside tcPolyExpr), except for any default - -- resolution it may have done, which is recorded in the - -- substitution. - returnTc (expr, lie) +tc_expr (ArithSeqIn seq@(From expr)) res_ty + = zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr elt_ty `thenM` \ expr' -> + + newMethodFromName (ArithSeqOrigin seq) + elt_ty enumFromName `thenM` \ enum_from -> + + returnM (ArithSeqOut (nlHsVar enum_from) (From expr')) + +tc_expr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty + = addErrCtxt (arithSeqCtxt in_expr) $ + 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 -> + + returnM (ArithSeqOut (nlHsVar enum_from_then) (FromThen expr1' expr2')) + + +tc_expr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty + = addErrCtxt (arithSeqCtxt in_expr) $ + 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 -> + + returnM (ArithSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2')) + +tc_expr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty + = addErrCtxt (arithSeqCtxt in_expr) $ + 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 -> + + returnM (ArithSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3')) + +tc_expr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty + = addErrCtxt (parrSeqCtxt in_expr) $ + zapToTyConApp parrTyCon 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 -> + + returnM (PArrSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2')) + +tc_expr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty + = addErrCtxt (parrSeqCtxt in_expr) $ + zapToTyConApp parrTyCon 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 -> + + returnM (PArrSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3')) + +tc_expr (PArrSeqIn _) _ + = panic "TcExpr.tcMonoExpr: Infinite parallel array!" + -- the parser shouldn't have generated it and the renamer shouldn't have + -- let it through \end{code} -Implicit Parameter bindings. + +%************************************************************************ +%* * + Template Haskell +%* * +%************************************************************************ \begin{code} -tcMonoExpr (HsWith expr binds) res_ty - = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) -> - tcIPBinds binds `thenTc` \ (binds', types, lie2) -> - partitionPredsOfLIE isBound lie `thenTc` \ (ips, lie', dict_binds) -> - let expr'' = if nullMonoBinds dict_binds - then expr' - else HsLet (mkMonoBind (revBinds dict_binds) [] NonRecursive) - expr' - in - tcCheckIPBinds binds' types ips `thenTc_` - returnTc (HsWith expr'' binds', lie' `plusLIE` lie2) - where isBound p - = case ipName_maybe p of - Just n -> n `elem` names - Nothing -> False - names = map fst binds - -- revBinds is used because tcSimplify outputs the bindings - -- out-of-order. it's not a problem elsewhere because these - -- bindings are normally used in a recursive let - -- ZZ probably need to find a better solution - revBinds (b1 `AndMonoBinds` b2) = - (revBinds b2) `AndMonoBinds` (revBinds b1) - revBinds b = b - -tcIPBinds ((name, expr) : binds) - = newTyVarTy openTypeKind `thenTc` \ ty -> - tcGetSrcLoc `thenTc` \ loc -> - let id = ipToId name ty loc in - tcMonoExpr expr ty `thenTc` \ (expr', lie) -> - zonkTcType ty `thenTc` \ ty' -> - tcIPBinds binds `thenTc` \ (binds', types, lie2) -> - returnTc ((id, expr') : binds', ty : types, lie `plusLIE` lie2) -tcIPBinds [] = returnTc ([], [], emptyLIE) - -tcCheckIPBinds binds types ips - = foldrTc tcCheckIPBind (getIPsOfLIE ips) (zip binds types) - --- ZZ how do we use the loc? -tcCheckIPBind bt@((v, _), t1) ((n, t2) : ips) | getName v == n - = unifyTauTy t1 t2 `thenTc_` - tcCheckIPBind bt ips `thenTc` \ ips' -> - returnTc ips' -tcCheckIPBind bt (ip : ips) - = tcCheckIPBind bt ips `thenTc` \ ips' -> - returnTc (ip : ips') -tcCheckIPBind bt [] - = returnTc [] +#ifdef GHCI /* Only if bootstrapped */ + -- Rename excludes these cases otherwise +tc_expr (HsSpliceE splice) res_ty = tcSpliceExpr splice res_ty +tc_expr (HsBracket brack) res_ty = do { e <- tcBracket brack res_ty + ; return (unLoc e) } +#endif /* GHCI */ \end{code} -Typecheck expression which in most cases will be an Id. + +%************************************************************************ +%* * + Catch-all +%* * +%************************************************************************ \begin{code} -tcExpr_id :: RenamedHsExpr - -> TcM (TcExpr, - LIE, - TcType) -tcExpr_id id_expr - = case id_expr of - HsVar name -> tcId name `thenNF_Tc` \ stuff -> - returnTc stuff - other -> newTyVarTy openTypeKind `thenNF_Tc` \ id_ty -> - tcMonoExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) -> - returnTc (id_expr', lie_id, id_ty) +tc_expr other _ = pprPanic "tcMonoExpr" (ppr other) \end{code} + %************************************************************************ %* * \subsection{@tcApp@ typchecks an application} @@ -708,79 +605,124 @@ tcExpr_id id_expr \begin{code} -tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args - -> TcType -- Expected result type of application - -> TcM (TcExpr, [TcExpr], -- Translated fun and args - LIE) - -tcApp fun args res_ty - = -- First type-check the function - tcExpr_id fun `thenTc` \ (fun', lie_fun, fun_ty) -> - - tcAddErrCtxt (wrongArgsCtxt "too many" fun args) ( - split_fun_ty fun_ty (length args) - ) `thenTc` \ (expected_arg_tys, actual_result_ty) -> +tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args + -> Expected TcRhoType -- Expected result type of application + -> TcM (HsExpr TcId) -- Translated fun and args - -- Unify with expected result before type-checking the args - -- This is when we might detect a too-few args situation - tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) ( - unifyTauTy res_ty actual_result_ty - ) `thenTc_` - - -- Now typecheck the args - mapAndUnzipTc (tcArg fun) - (zip3 args expected_arg_tys [1..]) `thenTc` \ (args', lie_args_s) -> - - -- Check that the result type doesn't have any nested for-alls. - -- For example, a "build" on its own is no good; it must be applied to something. - checkTc (isTauTy actual_result_ty) - (lurkingRank2Err fun actual_result_ty) `thenTc_` - - returnTc (fun', args', lie_fun `plusLIE` plusLIEs lie_args_s) +tcApp (L _ (HsApp e1 e2)) args res_ty + = tcApp e1 (e2:args) res_ty -- Accumulate the arguments +tcApp fun args res_ty + = do { (fun', fun_tvs, fun_tau) <- tcFun fun -- Type-check the function + + -- Extract its argument types + ; (expected_arg_tys, actual_res_ty) + <- addErrCtxt (wrongArgsCtxt "too many" fun args) $ do + { traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_tau)) + ; unifyFunTys (length args) fun_tau } + + + ; case res_ty of + Check _ -> do -- Connect to result type first + -- See Note [Push result type in] + { co_fn <- tcResult fun args res_ty actual_res_ty + ; the_app' <- tcArgs fun fun' args expected_arg_tys + ; traceTc (text "tcApp: check" <+> vcat [ppr fun <+> ppr args, + ppr the_app', ppr actual_res_ty]) + ; returnM (co_fn <$> the_app') } + + Infer _ -> do -- Type check args first, then + -- refine result type, then do tcResult + { the_app' <- tcArgs fun fun' args expected_arg_tys + ; subst <- refineTyVars fun_tvs + ; let actual_res_ty' = substTy subst actual_res_ty + ; co_fn <- tcResult fun args res_ty actual_res_ty' + ; traceTc (text "tcApp: infer" <+> vcat [ppr fun <+> ppr args, ppr the_app', + ppr actual_res_ty, ppr actual_res_ty']) + ; returnM (co_fn <$> the_app') } + } + +-- Note [Push result type in] +-- +-- 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_res_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.] + +---------------- +tcFun :: LHsExpr Name -> TcM (LHsExpr TcId, [TcTyVar], TcRhoType) +-- Instantiate the function, returning the type variables used +-- If the function isn't simple, infer its type, and return no +-- type variables +tcFun (L loc (HsVar f)) = setSrcSpan loc $ do + { (fun', tvs, fun_tau) <- tcId f + ; return (L loc fun', tvs, fun_tau) } +tcFun fun = do { (fun', fun_tau) <- tcInfer (tcMonoExpr fun) + ; return (fun', [], fun_tau) } + +---------------- +tcArgs :: LHsExpr Name -- The function (for error messages) + -> LHsExpr TcId -- The function (to build into result) + -> [LHsExpr Name] -> [TcSigmaType] -- Actual arguments and expected arg types + -> TcM (HsExpr TcId) -- Resulting application + +tcArgs fun fun' args expected_arg_tys + = do { args' <- mappM (tcArg fun) (zip3 args expected_arg_tys [1..]) + ; return (unLoc (foldl mkHsApp fun' args')) } + +tcArg :: LHsExpr Name -- The function (for error messages) + -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type + -> TcM (LHsExpr TcId) -- Resulting argument +tcArg fun (arg, ty, arg_no) = addErrCtxt (funAppCtxt fun arg arg_no) + (tcCheckSigma arg ty) + +---------------- +tcResult fun args res_ty actual_res_ty + = addErrCtxtM (checkArgsCtxt fun args res_ty actual_res_ty) + (tcSubExp res_ty actual_res_ty) + +---------------- -- 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 - = zonkTcType expected_res_ty `thenNF_Tc` \ exp_ty' -> - zonkTcType actual_res_ty `thenNF_Tc` \ act_ty' -> +-- 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 (Infer _) actual_res_ty tidy_env + = return (tidy_env, ptext SLIT("Urk infer")) + +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 (env1, exp_ty'') = tidyOpenType tidy_env exp_ty' (env2, act_ty'') = tidyOpenType env1 act_ty' - (exp_args, _) = splitFunTys exp_ty'' - (act_args, _) = splitFunTys act_ty'' - - message | length exp_args < length act_args = wrongArgsCtxt "too few" fun args - | length exp_args > length act_args = wrongArgsCtxt "too many" fun args - | otherwise = appCtxt fun args - in - returnNF_Tc (env2, message) - + (exp_args, _) = tcSplitFunTys exp_ty'' + (act_args, _) = tcSplitFunTys act_ty'' -split_fun_ty :: TcType -- The type of the function - -> Int -- Number of arguments - -> TcM ([TcType], -- Function argument types - TcType) -- Function result types - -split_fun_ty fun_ty 0 - = returnTc ([], fun_ty) - -split_fun_ty fun_ty n - = -- Expect the function to have type A->B - unifyFunTy fun_ty `thenTc` \ (arg_ty, res_ty) -> - split_fun_ty res_ty (n-1) `thenTc` \ (arg_tys, final_res_ty) -> - returnTc (arg_ty:arg_tys, final_res_ty) -\end{code} - -\begin{code} -tcArg :: RenamedHsExpr -- The function (for error messages) - -> (RenamedHsExpr, TcType, Int) -- Actual argument and expected arg type - -> TcM (TcExpr, LIE) -- Resulting argument and LIE + len_act_args = length act_args + len_exp_args = length exp_args -tcArg the_fun (arg, expected_arg_ty, arg_no) - = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $ - tcExpr arg expected_arg_ty + message | len_exp_args < len_act_args = wrongArgsCtxt "too few" fun args + | len_exp_args > len_act_args = wrongArgsCtxt "too many" fun args + | otherwise = appCtxt fun args + in + returnM (env2, message) \end{code} @@ -790,96 +732,149 @@ tcArg the_fun (arg, expected_arg_ty, arg_no) %* * %************************************************************************ -Between the renamer and the first invocation of the UsageSP inference, -identifiers read from interface files will have usage information in -their types, whereas other identifiers will not. The unannotTy here -in @tcId@ prevents this information from pointlessly propagating -further prior to the first usage inference. +tcId instantiates an occurrence of an Id. +The instantiate_it loop runs round instantiating the Id. +It has to be a loop because we are now prepared to entertain +types like + f:: forall a. Eq a => forall b. Baz b => tau +We want to instantiate this to + f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)} + +The -fno-method-sharing flag controls what happens so far as the LIE +is concerned. The default case is that for an overloaded function we +generate a "method" Id, and add the Method Inst to the LIE. So you get +something like + f :: Num a => a -> a + f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x +If you specify -fno-method-sharing, the dictionary application +isn't shared, so we get + f :: Num a => a -> a + f = /\a (d:Num a) (x:a) -> (+) a d x x +This gets a bit less sharing, but + a) it's better for RULEs involving overloaded functions + b) perhaps fewer separated lambdas \begin{code} -tcId :: Name -> NF_TcM (TcExpr, LIE, TcType) - -tcId name - = -- Look up the Id and instantiate its type - tcLookup name `thenNF_Tc` \ thing -> - case thing of - ATcId tc_id -> instantiate_it (OccurrenceOf tc_id) tc_id (idType tc_id) - AGlobal (AnId id) -> tcInstId id `thenNF_Tc` \ (tyvars, theta, tau) -> - instantiate_it2 (OccurrenceOf id) id tyvars theta tau - +tcId :: Name -> TcM (HsExpr TcId, [TcTyVar], TcRhoType) + -- Return the type variables at which the function + -- is instantiated, as well as the translated variable and its type + +tcId id_name -- Look up the Id and instantiate its type + = tcLookup id_name `thenM` \ thing -> + case thing of { + AGlobal (ADataCon con) -- Similar, but instantiate the stupid theta too + -> do { (expr, tvs, tau) <- instantiate (dataConWrapId con) + ; tcInstStupidTheta con (mkTyVarTys tvs) + -- Remember to chuck in the constraints from the "silly context" + ; return (expr, tvs, tau) } + + ; AGlobal (AnId id) -> instantiate id + -- A global cannot possibly be ill-staged + -- nor does it need the 'lifting' treatment + + ; ATcId id th_level proc_level + -> do { checkProcLevel id proc_level + ; tc_local_id id th_level } + + -- THis + ; other -> failWithTc (ppr other <+> ptext SLIT("used where a value identifer was expected")) + } where - -- The instantiate_it loop runs round instantiating the Id. - -- It has to be a loop because we are now prepared to entertain - -- types like - -- f:: forall a. Eq a => forall b. Baz b => tau - -- We want to instantiate this to - -- f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)} - instantiate_it orig fun ty - = tcInstTcType ty `thenNF_Tc` \ (tyvars, rho) -> - tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) -> - instantiate_it2 orig fun tyvars theta tau - - instantiate_it2 orig fun tyvars theta tau - = if null theta then -- Is it overloaded? - returnNF_Tc (mkHsTyApp (HsVar fun) arg_tys, emptyLIE, tau) - else - -- Yes, it's overloaded - instOverloadedFun orig fun arg_tys theta tau `thenNF_Tc` \ (fun', lie1) -> - instantiate_it orig fun' tau `thenNF_Tc` \ (expr, lie2, final_tau) -> - returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau) - - where - arg_tys = mkTyVarTys tyvars -\end{code} - -%************************************************************************ -%* * -\subsection{@tcDoStmts@ typechecks a {\em list} of do statements} -%* * -%************************************************************************ -\begin{code} -tcDoStmts do_or_lc stmts src_loc res_ty - = -- get the Monad and MonadZero classes - -- create type consisting of a fresh monad tyvar - ASSERT( not (null stmts) ) - tcAddSrcLoc src_loc $ - - newTyVarTy (mkArrowKind boxedTypeKind boxedTypeKind) `thenNF_Tc` \ m -> - newTyVarTy boxedTypeKind `thenNF_Tc` \ elt_ty -> - unifyTauTy res_ty (mkAppTy m elt_ty) `thenTc_` - - -- If it's a comprehension we're dealing with, - -- force it to be a list comprehension. - -- (as of Haskell 98, monad comprehensions are no more.) - (case do_or_lc of - ListComp -> unifyListTy res_ty `thenTc_` returnTc () - _ -> returnTc ()) `thenTc_` - - tcStmts do_or_lc (mkAppTy m) stmts elt_ty `thenTc` \ (stmts', stmts_lie) -> - - -- Build the then and zero methods in case we need them - -- It's important that "then" and "return" appear just once in the final LIE, - -- not only for typechecker efficiency, but also because otherwise during - -- simplification we end up with silly stuff like - -- then = case d of (t,r) -> t - -- then = then - -- where the second "then" sees that it already exists in the "available" stuff. - -- - tcLookupGlobalId returnMClassOpName `thenNF_Tc` \ return_sel_id -> - tcLookupGlobalId thenMClassOpName `thenNF_Tc` \ then_sel_id -> - tcLookupGlobalId failMClassOpName `thenNF_Tc` \ fail_sel_id -> - newMethod DoOrigin return_sel_id [m] `thenNF_Tc` \ (return_lie, return_id) -> - newMethod DoOrigin then_sel_id [m] `thenNF_Tc` \ (then_lie, then_id) -> - newMethod DoOrigin fail_sel_id [m] `thenNF_Tc` \ (fail_lie, fail_id) -> - let - monad_lie = then_lie `plusLIE` return_lie `plusLIE` fail_lie - in - returnTc (HsDoOut do_or_lc stmts' return_id then_id fail_id res_ty src_loc, - stmts_lie `plusLIE` monad_lie) +#ifndef GHCI + tc_local_id id th_bind_lvl -- Non-TH case + = instantiate id + +#else /* GHCI and TH is on */ + tc_local_id id th_bind_lvl -- TH case + = -- Check for cross-stage lifting + getStage `thenM` \ use_stage -> + case use_stage of + Brack use_lvl ps_var lie_var + | use_lvl > th_bind_lvl + -> if isExternalName id_name then + -- Top-level identifiers in this module, + -- (which have External Names) + -- are just like the imported case: + -- no need for the 'lifting' treatment + -- E.g. this is fine: + -- f x = x + -- g y = [| f 3 |] + -- But we do need to put f into the keep-alive + -- set, because after desugaring the code will + -- only mention f's *name*, not f itself. + keepAliveTc id_name `thenM_` + instantiate id + + else -- Nested identifiers, such as 'x' in + -- E.g. \x -> [| h x |] + -- We must behave as if the reference to x was + -- h $(lift x) + -- We use 'x' itself as the splice proxy, used by + -- the desugarer to stitch it all back together. + -- If 'x' occurs many times we may get many identical + -- bindings of the same splice proxy, but that doesn't + -- matter, although it's a mite untidy. + let + id_ty = idType id + in + checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_` + -- If x is polymorphic, its occurrence sites might + -- have different instantiations, so we can't use plain + -- 'x' as the splice proxy name. I don't know how to + -- solve this, and it's probably unimportant, so I'm + -- just going to flag an error for now + + setLIEVar lie_var ( + newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift -> + -- Put the 'lift' constraint into the right LIE + + -- Update the pending splices + readMutVar ps_var `thenM` \ ps -> + writeMutVar ps_var ((id_name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_` + + returnM (HsVar id, [], id_ty)) + + other -> + checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_` + instantiate id +#endif /* GHCI */ + + instantiate :: TcId -> TcM (HsExpr TcId, [TcTyVar], TcRhoType) + instantiate fun_id = loop (HsVar fun_id) [] (idType fun_id) + + loop (HsVar fun_id) tvs fun_ty + | want_method_inst fun_ty + = tcInstType fun_ty `thenM` \ (tyvars, theta, tau) -> + newMethodWithGivenTy orig fun_id + (mkTyVarTys tyvars) theta tau `thenM` \ meth_id -> + loop (HsVar meth_id) (tvs ++ tyvars) tau + + loop fun tvs fun_ty + | isSigmaTy fun_ty + = tcInstCall orig fun_ty `thenM` \ (inst_fn, new_tvs, tau) -> + loop (inst_fn <$> fun) (tvs ++ new_tvs) tau + + | otherwise + = returnM (fun, tvs, fun_ty) + + -- Hack Alert (want_method_inst)! + -- If f :: (%x :: T) => Int -> Int + -- Then if we have two separate calls, (f 3, f 4), we cannot + -- make a method constraint that then gets shared, thus: + -- let m = f %x in (m 3, m 4) + -- because that loses the linearity of the constraint. + -- The simplest thing to do is never to construct a method constraint + -- in the first place that has a linear implicit parameter in it. + want_method_inst fun_ty + | opt_NoMethodSharing = False + | otherwise = case tcSplitSigmaTy fun_ty of + (_,[],_) -> False -- Not overloaded + (_,theta,_) -> not (any isLinearPred theta) + + orig = OccurrenceOf id_name \end{code} - %************************************************************************ %* * \subsection{Record bindings} @@ -907,85 +902,92 @@ This extends OK when the field types are universally quantified. tcRecordBinds :: TyCon -- Type constructor for the record -> [TcType] -- Args of this type constructor - -> RenamedRecordBinds - -> TcM (TcRecordBinds, LIE) + -> HsRecordBinds Name + -> TcM (HsRecordBinds TcId) tcRecordBinds tycon ty_args rbinds - = mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) -> - returnTc (rbinds', plusLIEs lies) + = mappM do_bind rbinds where - tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args + tenv = zipTopTvSubst (tyConTyVars tycon) ty_args - do_bind (field_lbl_name, rhs, pun_flag) - = tcLookupGlobalId field_lbl_name `thenNF_Tc` \ sel_id -> + do_bind (L loc field_lbl, rhs) + = addErrCtxt (fieldCtxt field_lbl) $ let - field_lbl = recordSelectorFieldLabel sel_id - field_ty = substTy tenv (fieldLabelType field_lbl) + field_ty = tyConFieldType tycon field_lbl + field_ty' = substTy tenv field_ty in + tcCheckSigma rhs field_ty' `thenM` \ rhs' -> + tcLookupId field_lbl `thenM` \ sel_id -> ASSERT( isRecordSelector sel_id ) + returnM (L loc sel_id, rhs') + +tyConFieldType :: TyCon -> FieldLabel -> Type +tyConFieldType tycon field_lbl + = case [ty | (f,ty,_) <- tyConFields tycon, f == field_lbl] of + (ty:other) -> ASSERT( null other) ty -- This lookup and assertion will surely succeed, because -- we check that the fields are indeed record selectors -- before calling tcRecordBinds - ASSERT2( fieldLabelTyCon field_lbl == tycon, ppr field_lbl ) - -- The caller of tcRecordBinds has already checked - -- that all the fields come from the same type - - tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) -> - - returnTc ((sel_id, rhs', pun_flag), lie) badFields rbinds data_con - = [field_name | (field_name, _, _) <- rbinds, - not (field_name `elem` field_names) - ] + = filter (not . (`elem` field_names)) (recBindFields rbinds) where - field_names = map fieldLabelName (dataConFieldLabels data_con) - -missingStrictFields rbinds data_con - = [ fn | fn <- strict_field_names, - not (fn `elem` field_names_used) - ] - where - field_names_used = [ field_name | (field_name, _, _) <- rbinds ] - strict_field_names = mapMaybe isStrict field_info - - isStrict (fl, MarkedStrict) = Just (fieldLabelName fl) - isStrict _ = Nothing + field_names = dataConFieldLabels data_con + +checkMissingFields :: DataCon -> HsRecordBinds Name -> TcM () +checkMissingFields data_con rbinds + | null field_labels -- Not declared as a record; + -- But C{} is still valid if no strict fields + = if any isMarkedStrict field_strs then + -- Illegal if any arg is strict + addErrTc (missingStrictFields data_con []) + else + returnM () + + | otherwise -- A record + = checkM (null missing_s_fields) + (addErrTc (missingStrictFields data_con missing_s_fields)) `thenM_` - field_info = zip (dataConFieldLabels data_con) - (dataConStrictMarks data_con) + doptM Opt_WarnMissingFields `thenM` \ warn -> + checkM (not (warn && notNull missing_ns_fields)) + (warnTc True (missingFields data_con missing_ns_fields)) -missingFields rbinds data_con - = [ fn | fn <- non_strict_field_names, not (fn `elem` field_names_used) ] where - field_names_used = [ field_name | (field_name, _, _) <- rbinds ] - - -- missing strict fields have already been flagged as - -- being so, so leave them out here. - non_strict_field_names = mapMaybe isn'tStrict field_info - - isn'tStrict (fl, MarkedStrict) = Nothing - isn'tStrict (fl, _) = Just (fieldLabelName fl) - - field_info = zip (dataConFieldLabels data_con) - (dataConStrictMarks data_con) - + missing_s_fields + = [ fl | (fl, str) <- field_info, + isMarkedStrict str, + not (fl `elem` field_names_used) + ] + missing_ns_fields + = [ fl | (fl, str) <- field_info, + not (isMarkedStrict str), + not (fl `elem` field_names_used) + ] + + field_names_used = recBindFields rbinds + field_labels = dataConFieldLabels data_con + + field_info = zipEqual "missingFields" + field_labels + field_strs + + 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], LIE) +tcCheckRhos :: [LHsExpr Name] -> [TcType] -> TcM [LHsExpr TcId] -tcMonoExprs [] [] = returnTc ([], emptyLIE) -tcMonoExprs (expr:exprs) (ty:tys) - = tcMonoExpr expr ty `thenTc` \ (expr', lie1) -> - tcMonoExprs exprs tys `thenTc` \ (exprs', lie2) -> - returnTc (expr':exprs', lie1 `plusLIE` lie2) +tcCheckRhos [] [] = returnM [] +tcCheckRhos (expr:exprs) (ty:tys) + = tcCheckRho expr ty `thenM` \ expr' -> + tcCheckRhos exprs tys `thenM` \ exprs' -> + returnM (expr':exprs') \end{code} @@ -998,16 +1000,10 @@ tcMonoExprs (expr:exprs) (ty:tys) Overloaded literals. \begin{code} -tcLit :: HsLit -> TcType -> TcM (TcExpr, LIE) -tcLit (HsLitLit s _) res_ty - = tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass -> - newClassDicts (LitLitOrigin (_UNPK_ s)) - [(cCallableClass,[res_ty])] `thenNF_Tc` \ (dicts, _) -> - returnTc (HsLit (HsLitLit s res_ty), dicts) - +tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId) tcLit lit res_ty - = unifyTauTy res_ty (simpleHsLitTy lit) `thenTc_` - returnTc (HsLit lit, emptyLIE) + = zapExpectedTo res_ty (hsLitType lit) `thenM_` + returnM (HsLit lit) \end{code} @@ -1017,68 +1013,48 @@ tcLit lit res_ty %* * %************************************************************************ -Mini-utils: - -\begin{code} -pp_nest_hang :: String -> SDoc -> SDoc -pp_nest_hang lbl stuff = nest 2 (hang (text lbl) 4 stuff) -\end{code} - Boring and alphabetical: \begin{code} arithSeqCtxt expr = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr) +parrSeqCtxt expr + = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr) + caseCtxt expr = hang (ptext SLIT("In the case expression:")) 4 (ppr expr) caseScrutCtxt expr = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr) -exprSigCtxt expr - = hang (ptext SLIT("In an expression with a type signature:")) - 4 (ppr expr) - -listCtxt expr - = hang (ptext SLIT("In the list element:")) 4 (ppr expr) - -predCtxt expr - = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr) - -sectionRAppCtxt expr - = hang (ptext SLIT("In the right section:")) 4 (ppr expr) +exprCtxt expr + = hang (ptext SLIT("In the expression:")) 4 (ppr expr) -sectionLAppCtxt expr - = hang (ptext SLIT("In the left section:")) 4 (ppr expr) +fieldCtxt field_name + = ptext SLIT("In the") <+> quotes (ppr field_name) <+> ptext SLIT("field of a record") funAppCtxt fun arg arg_no = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"), quotes (ppr fun) <> text ", namely"]) 4 (quotes (ppr arg)) -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 - <+> ptext SLIT("arguments in the call")) - 4 (parens (ppr the_app)) - where - the_app = foldl HsApp fun args -- Used in error messages +listCtxt expr + = hang (ptext SLIT("In the list element:")) 4 (ppr expr) + +parrCtxt expr + = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr) + +predCtxt expr + = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr) appCtxt fun args = ptext SLIT("In the application") <+> quotes (ppr the_app) 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]) + the_app = foldl mkHsApp fun args -- Used in error messages badFieldsUpd rbinds = hang (ptext SLIT("No constructor has all these fields:")) - 4 (pprQuotedList fields) - where - fields = [field | (field, _, _) <- rbinds] + 4 (pprQuotedList (recBindFields rbinds)) recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr @@ -1086,13 +1062,33 @@ recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr notSelector field = hsep [quotes (ppr field), ptext SLIT("is not a record selector")] -missingStrictFieldCon :: Name -> Name -> SDoc -missingStrictFieldCon con field - = hsep [ptext SLIT("Constructor") <+> quotes (ppr con), - ptext SLIT("does not have the required strict field"), quotes (ppr field)] +missingStrictFields :: DataCon -> [FieldLabel] -> SDoc +missingStrictFields con fields + = header <> rest + where + rest | null fields = empty -- Happens for non-record constructors + -- with strict fields + | otherwise = colon <+> pprWithCommas ppr fields + + header = ptext SLIT("Constructor") <+> quotes (ppr con) <+> + ptext SLIT("does not have the required strict field(s)") + +missingFields :: DataCon -> [FieldLabel] -> SDoc +missingFields con fields + = ptext SLIT("Fields of") <+> quotes (ppr con) <+> ptext SLIT("not initialised:") + <+> pprWithCommas ppr fields + +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 + <+> ptext SLIT("arguments in the call")) + 4 (parens (ppr the_app)) + where + the_app = foldl mkHsApp fun args -- Used in error messages -missingFieldCon :: Name -> Name -> SDoc -missingFieldCon con field - = hsep [ptext SLIT("Field") <+> quotes (ppr field), - ptext SLIT("is not initialised")] +#ifdef GHCI +polySpliceErr :: Id -> SDoc +polySpliceErr id + = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id) +#endif \end{code}