X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=cf94f27f19c2157dcbe917e09508dcd825735453;hb=c5a65b1704212e3f4354841ff480c660a3b51fb6;hp=603955947a055cc30cf9aa19909d569a1d59b92f;hpb=1d874e7c18d8b1bd46cbb27c3e146b092a64fc63;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 6039559..cf94f27 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -4,67 +4,71 @@ \section[TcExpr]{Typecheck an expression} \begin{code} -module TcExpr ( tcExpr, tcMonoExpr, tcId ) where +module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where #include "HsVersions.h" -import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), - HsMatchContext(..), HsDoContext(..), mkMonoBind - ) -import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds ) -import TcHsSyn ( TcExpr, TcRecordBinds, simpleHsLitTy ) - -import TcMonad -import TcUnify ( tcSub, tcGen, (<$>), - unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy - ) -import BasicTypes ( RecFlag(..), isMarkedStrict ) +#ifdef GHCI /* Only if bootstrapped */ +import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket ) +import Id ( Id ) +import TcType ( isTauTy ) +import TcEnv ( checkWellStaged ) +import HsSyn ( nlHsApp ) +import qualified DsMeta +#endif + +import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields, + HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar ) +import TcHsSyn ( hsLitType, mkHsDictApp, mkHsTyApp, (<$>) ) +import TcRnMonad +import TcUnify ( Expected(..), newHole, zapExpectedType, zapExpectedTo, tcSubExp, tcGen, + unifyFunTy, zapToListTy, zapToPArrTy, zapToTupleTy ) +import BasicTypes ( isMarkedStrict ) import Inst ( InstOrigin(..), - LIE, mkLIE, emptyLIE, unitLIE, plusLIE, plusLIEs, - newOverloadedLit, newMethod, newIPDict, - newDicts, - instToId, tcInstId + newOverloadedLit, newMethodFromName, newIPDict, + newDicts, newMethodWithGivenTy, + instToId, tcInstCall, tcInstDataCon ) import TcBinds ( tcBindsAndThen ) -import TcEnv ( tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe, - tcLookupTyCon, tcLookupDataCon, tcLookupId +import TcEnv ( tcLookup, tcLookupId, checkProcLevel, + tcLookupDataCon, tcLookupGlobalId ) -import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts ) -import TcMonoType ( tcHsSigType, UserTypeCtxt(..) ) +import TcArrows ( tcProc ) +import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) ) +import TcHsType ( tcHsSigType, UserTypeCtxt(..) ) import TcPat ( badFieldCon ) -import TcSimplify ( tcSimplifyIPs ) -import TcMType ( tcInstTyVars, newTyVarTy, newTyVarTys, zonkTcType ) -import TcType ( TcType, TcSigmaType, TcPhiType, - tcSplitFunTys, tcSplitTyConApp, - isSigmaTy, mkFunTy, mkAppTy, mkTyConTy, - mkTyConApp, mkClassPred, tcFunArgTy, - tyVarsOfTypes, - liftedTypeKind, openTypeKind, mkArrowKind, - tcSplitSigmaTy, tcTyConAppTyCon, - tidyOpenType +import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, zonkTcType ) +import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv), + tcSplitFunTys, tcSplitTyConApp, mkTyVarTys, + isSigmaTy, mkFunTy, mkFunTys, + mkTyConApp, tyVarsOfTypes, isLinearPred, + tcSplitSigmaTy, tidyOpenType ) +import Kind ( openTypeKind, liftedTypeKind, argTypeKind ) + import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon ) import Id ( idType, recordSelectorFieldLabel, isRecordSelector ) -import DataCon ( dataConFieldLabels, dataConSig, - dataConStrictMarks - ) +import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId ) import Name ( Name ) -import TyCon ( TyCon, tyConTyVars, isAlgTyCon, tyConDataCons ) +import TyCon ( TyCon, tyConTyVars, tyConTheta, tyConDataCons ) import Subst ( mkTopTyVarSubst, substTheta, substTy ) -import VarSet ( elemVarSet ) -import TysWiredIn ( boolTy, mkListTy, listTyCon ) -import PrelNames ( cCallableClassName, - cReturnableClassName, - enumFromName, enumFromThenName, +import VarSet ( emptyVarSet, elemVarSet ) +import TysWiredIn ( boolTy ) +import PrelNames ( enumFromName, enumFromThenName, enumFromToName, enumFromThenToName, - thenMName, failMName, returnMName, ioTyConName + enumFromToPName, enumFromThenToPName ) -import Outputable import ListSetOps ( minusList ) -import Util import CmdLineOpts import HscTypes ( TyThing(..) ) +import SrcLoc ( Located(..), unLoc, getLoc ) +import Util +import Outputable +import FastString +#ifdef DEBUG +import TyCon ( isAlgTyCon ) +#endif \end{code} %************************************************************************ @@ -74,47 +78,80 @@ import HscTypes ( TyThing(..) ) %************************************************************************ \begin{code} -tcExpr :: RenamedHsExpr -- Expession to type check - -> TcSigmaType -- Expected type (could be a polytpye) - -> TcM (TcExpr, LIE) -- Generalised expr with expected type, and 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} -tcExpr expr expected_ty - | not (isSigmaTy expected_ty) -- Monomorphic case - = tcMonoExpr expr expected_ty +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. - | otherwise - = tcGen expected_ty (tcMonoExpr expr) `thenTc` \ (gen_fn, expr', lie) -> - returnTc (gen_fn <$> expr', lie) +\begin{code} +tcCheckRho :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId) +tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty) + +tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType) +tcInferRho (L loc (HsVar name)) = addSrcSpan loc $ + do { (e,ty) <- tcId name; return (L loc e, ty)} +tcInferRho expr = newHole `thenM` \ hole -> + tcMonoExpr expr (Infer hole) `thenM` \ expr' -> + readMutVar hole `thenM` \ rho_ty -> + returnM (expr', rho_ty) \end{code} + %************************************************************************ %* * -\subsection{The TAUT rules for variables} +\subsection{The TAUT rules for variables}TcExpr %* * %************************************************************************ \begin{code} -tcMonoExpr :: RenamedHsExpr -- Expession to type check - -> TcPhiType -- Expected type (could be a type variable) +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 (TcExpr, LIE) + -> TcM (LHsExpr TcId) + +tcMonoExpr (L loc expr) res_ty + = addSrcSpan loc (do { expr' <- tc_expr expr res_ty + ; return (L loc expr') }) -tcMonoExpr (HsVar name) res_ty - = tcId name `thenNF_Tc` \ (expr', lie1, id_ty) -> - tcSub res_ty id_ty `thenTc` \ (co_fn, lie2) -> - returnTc (co_fn <$> expr', lie1 `plusLIE` lie2) +tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId) +tc_expr (HsVar name) res_ty + = tcId name `thenM` \ (expr', id_ty) -> + tcSubExp res_ty id_ty `thenM` \ co_fn -> + returnM (co_fn <$> expr') -tcMonoExpr (HsIPVar ip) res_ty +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.) - newTyVarTy openTypeKind `thenNF_Tc` \ ip_ty -> - newIPDict (IPOcc ip) ip ip_ty `thenNF_Tc` \ (ip', inst) -> - tcSub res_ty ip_ty `thenTc` \ (co_fn, lie) -> - returnNF_Tc (co_fn <$> HsIPVar ip', lie `plusLIE` unitLIE inst) + newTyVarTy 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} @@ -125,12 +162,20 @@ tcMonoExpr (HsIPVar ip) res_ty %************************************************************************ \begin{code} -tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty - = tcHsSigType ExprSigCtxt poly_ty `thenTc` \ sig_tc_ty -> - tcAddErrCtxt (exprSigCtxt in_expr) $ - tcExpr expr sig_tc_ty `thenTc` \ (expr', lie1) -> - tcSub res_ty sig_tc_ty `thenTc` \ (co_fn, lie2) -> - returnTc (co_fn <$> expr', lie1 `plusLIE` lie2) +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 <$> unLoc expr') + -- ToDo: nasty unLoc + +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} @@ -141,18 +186,29 @@ tcMonoExpr in_expr@(ExprWithTySig expr poly_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 (HsPar expr) res_ty = tcMonoExpr expr res_ty +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') -tcMonoExpr (NegApp expr neg_name) res_ty - = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty +tc_expr (HsLit lit) res_ty = tcLit lit res_ty -tcMonoExpr (HsLam match) res_ty - = tcMatchLambda match res_ty `thenTc` \ (match',lie) -> - returnTc (HsLam match', lie) +tc_expr (HsOverLit lit) res_ty + = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' -> + newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr -> + returnM (unLoc lit_expr) -- ToDo: nasty unLoc -tcMonoExpr (HsApp e1 e2) res_ty +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} @@ -167,113 +223,48 @@ a type error will occur if they aren't. -- or just -- op e -tcMonoExpr in_expr@(SectionL arg1 op) res_ty - = tcExpr_id op `thenTc` \ (op', lie1, op_ty) -> - split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) -> - tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2) -> - tcAddErrCtxt (exprCtxt in_expr) $ - tcSub res_ty (mkFunTy arg2_ty op_res_ty) `thenTc` \ (co_fn, lie3) -> - returnTc (co_fn <$> SectionL arg1' op', lie1 `plusLIE` lie2 `plusLIE` lie3) +tc_expr in_expr@(SectionL arg1 op) res_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) $ + 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 arg2) res_ty - = tcExpr_id op `thenTc` \ (op', lie1, op_ty) -> - split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) -> - tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2) -> - tcAddErrCtxt (exprCtxt in_expr) $ - tcSub res_ty (mkFunTy arg1_ty op_res_ty) `thenTc` \ (co_fn, lie3) -> - returnTc (co_fn <$> SectionR op' arg2', lie1 `plusLIE` lie2 `plusLIE` lie3) +tc_expr in_expr@(SectionR op arg2) res_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) $ + tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn -> + returnM (co_fn <$> SectionR op' arg2') -- equivalent to (op e1) e2: -tcMonoExpr in_expr@(OpApp arg1 op fix arg2) res_ty - = tcExpr_id op `thenTc` \ (op', lie1, op_ty) -> - split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) -> - tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2a) -> - tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2b) -> - tcAddErrCtxt (exprCtxt in_expr) $ - tcSub res_ty op_res_ty `thenTc` \ (co_fn, lie3) -> - returnTc (OpApp arg1' op' fix arg2', - lie1 `plusLIE` lie2a `plusLIE` lie2b `plusLIE` lie3) -\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 e0@(HsCCall lbl args may_gc is_casm ignored_fake_result_ty) res_ty - - = getDOptsTc `thenNF_Tc` \ 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."]) - `thenTc_` - - -- 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) - = newDicts (CCallOrigin (_UNPK_ lbl) (Just arg)) - [mkClassPred 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 - - -- Arguments - let tv_idxs | null args = [] - | otherwise = [1..length args] - in - newTyVarTys (length tv_idxs) openTypeKind `thenNF_Tc` \ arg_tys -> - tcMonoExprs args arg_tys `thenTc` \ (args', args_lie) -> - - -- 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 `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 -> - newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenNF_Tc` \ ccres_dict -> - returnTc (HsCCall lbl args' may_gc is_casm io_result_ty, - mkLIE (ccres_dict ++ concat ccarg_dicts_s) `plusLIE` args_lie) +tc_expr in_expr@(OpApp arg1 op fix arg2) res_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' -> + 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) + (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) $ +tc_expr in_expr@(HsCase scrut matches) res_ty + = addErrCtxt (caseCtxt in_expr) $ -- Typecheck the case alternatives first. -- The case patterns tend to give good type info to use @@ -281,91 +272,99 @@ 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 `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} -\begin{code} -tcMonoExpr expr@(HsDo do_or_lc stmts src_loc) res_ty - = tcDoStmts do_or_lc stmts src_loc res_ty -\end{code} + tcMatchesCase match_ctxt matches res_ty `thenM` \ (scrut_ty, matches') -> -\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 (ExplicitList elt_ty exprs', plusLIEs lies) + addErrCtxt (caseScrutCtxt scrut) ( + tcCheckRho scrut scrut_ty + ) `thenM` \ scrut' -> + + 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 - = 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) -> + = addErrCtxt (listCtxt expr) $ + tcCheckRho expr elt_ty + +tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty + = 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) $ + tcCheckRho expr elt_ty + +tc_expr (ExplicitTuple exprs boxity) res_ty + = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys -> + tcCheckRhos exprs arg_tys `thenM` \ exprs' -> + returnM (ExplicitTuple exprs' boxity) + +tc_expr (HsProc pat cmd) res_ty + = tcProc pat cmd res_ty `thenM` \ (pat', cmd') -> + returnM (HsProc pat' cmd') +\end{code} + +%************************************************************************ +%* * + Record construction and update +%* * +%************************************************************************ + +\begin{code} +tc_expr expr@(RecordCon con@(L _ con_name) rbinds) res_ty + = addErrCtxt (recordConCtxt expr) $ + addLocM tcId con `thenM` \ (con_expr, con_tau) -> let (_, record_ty) = tcSplitFunTys con_tau (tycon, ty_args) = tcSplitTyConApp record_ty in ASSERT( isAlgTyCon tycon ) - unifyTauTy res_ty record_ty `thenTc_` + 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, missing_fields) = missingFields rbinds data_con - in - checkTcM (null missing_s_fields) - (mapNF_Tc (addErrTc . missingStrictFieldCon con_name) missing_s_fields `thenNF_Tc_` - returnNF_Tc ()) `thenNF_Tc_` - doptsTc Opt_WarnMissingFields `thenNF_Tc` \ warn -> - checkTcM (not (warn && 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) + getSrcSpanM `thenM` \ loc -> + 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: @@ -393,45 +392,43 @@ 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 = [ addSrcSpan 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 -- It's OK to use the non-tc splitters here (for a selector) - (Just (AnId sel_id) : _) = maybe_sel_ids - (_, _, tau) = tcSplitSigmaTy (idType sel_id) -- Selectors can be overloaded - -- when the data type has a context - data_ty = tcFunArgTy tau -- Must succeed since sel_id is a selector - tycon = tcTyConAppTyCon data_ty - data_cons = tyConDataCons tycon - (con_tyvars, _, _, _, _, _) = dataConSig (head data_cons) + 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 + tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars in - tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) -> + tcInstTyVars VanillaTv 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. @@ -440,8 +437,8 @@ 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 @@ -450,7 +447,7 @@ 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 = map recordSelectorFieldLabel (recBindFields rbinds') con_field_lbls_s = map dataConFieldLabels data_cons -- A constructor is only relevant to this process if @@ -462,114 +459,141 @@ tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls) mk_inst_ty (tyvar, result_inst_ty) - | tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type - | otherwise = newTyVarTy liftedTypeKind -- Fresh type + | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type + | otherwise = newTyVarTy liftedTypeKind -- Fresh type in - mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys -> + mappM mk_inst_ty (zip 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' = substTheta inst_env theta + theta' = substTheta inst_env (tyConTheta tycon) in - newDicts RecordUpdOrigin theta' `thenNF_Tc` \ dicts -> + newDicts RecordUpdOrigin theta' `thenM` \ dicts -> + extendLIEs dicts `thenM_` -- Phew! - returnTc (RecordUpdOut record_expr' record_ty result_record_ty (map instToId dicts) rbinds', - mkLIE dicts `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 enumFromName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - sel_id [elt_ty] `thenNF_Tc` \ enum_from -> - - returnTc (ArithSeqOut (HsVar (instToId enum_from)) (From expr'), - lie1 `plusLIE` unitLIE enum_from) - -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 enumFromThenName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_then -> - - returnTc (ArithSeqOut (HsVar (instToId enum_from_then)) - (FromThen expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_then) - -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 enumFromToName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_to -> - - returnTc (ArithSeqOut (HsVar (instToId enum_from_to)) - (FromTo expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_to) - -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 enumFromThenToName `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ eft -> - - returnTc (ArithSeqOut (HsVar (instToId eft)) - (FromThenTo expr1' expr2' expr3'), - lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft) + returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds') \end{code} + %************************************************************************ %* * -\subsection{Implicit Parameter bindings} + Arithmetic sequences e.g. [a,b..] + and their parallel-array counterparts e.g. [: a,b.. :] + %* * %************************************************************************ \begin{code} -tcMonoExpr (HsWith expr binds) res_ty - = tcMonoExpr expr res_ty `thenTc` \ (expr', expr_lie) -> - mapAndUnzip3Tc tcIPBind binds `thenTc` \ (avail_ips, binds', bind_lies) -> +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) $ + 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 -> + + 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) $ + 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 -> + + 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} - -- If the binding binds ?x = E, we must now - -- discharge any ?x constraints in expr_lie - tcSimplifyIPs avail_ips expr_lie `thenTc` \ (expr_lie', dict_binds) -> - let - expr'' = HsLet (mkMonoBind dict_binds [] Recursive) expr' - in - returnTc (HsWith expr'' binds', expr_lie' `plusLIE` plusLIEs bind_lies) - -tcIPBind (ip, expr) - = newTyVarTy openTypeKind `thenTc` \ ty -> - tcGetSrcLoc `thenTc` \ loc -> - newIPDict (IPBind ip) ip ty `thenNF_Tc` \ (ip', ip_inst) -> - tcMonoExpr expr ty `thenTc` \ (expr', lie) -> - returnTc (ip_inst, (ip', expr'), lie) + +%************************************************************************ +%* * + Template Haskell +%* * +%************************************************************************ + +\begin{code} +#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} + +%************************************************************************ +%* * + Catch-all +%* * +%************************************************************************ + +\begin{code} +tc_expr other _ = pprPanic "tcMonoExpr" (ppr other) +\end{code} + + %************************************************************************ %* * \subsection{@tcApp@ typchecks an application} @@ -578,43 +602,61 @@ tcIPBind (ip, expr) \begin{code} -tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args - -> TcType -- Expected result type of application - -> TcM (TcExpr, LIE) -- Translated fun and args +tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args + -> Expected TcRhoType -- Expected result type of application + -> TcM (HsExpr TcId) -- Translated fun and args -tcApp (HsApp e1 e2) args res_ty +tcApp (L _ (HsApp e1 e2)) args res_ty = tcApp e1 (e2:args) res_ty -- Accumulate the arguments tcApp fun args res_ty = -- First type-check the function - tcExpr_id fun `thenTc` \ (fun', lie_fun, fun_ty) -> + tcInferRho fun `thenM` \ (fun', fun_ty) -> - tcAddErrCtxt (wrongArgsCtxt "too many" fun args) ( + addErrCtxt (wrongArgsCtxt "too many" fun args) ( + traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_` split_fun_ty fun_ty (length args) - ) `thenTc` \ (expected_arg_tys, actual_result_ty) -> + ) `thenM` \ (expected_arg_tys, actual_result_ty) -> - -- Now typecheck the args - mapAndUnzipTc (tcArg fun) - (zip3 args expected_arg_tys [1..]) `thenTc` \ (args', lie_args_s) -> - - -- 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.) - tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) - (tcSub res_ty actual_result_ty) `thenTc` \ (co_fn, lie_res) -> + -- [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.] - returnTc (co_fn <$> foldl HsApp fun' args', - lie_res `plusLIE` lie_fun `plusLIE` plusLIEs lie_args_s) + addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) + (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn -> + + -- Now typecheck the args + mappM (tcArg fun) + (zip3 args expected_arg_tys [1..]) `thenM` \ args' -> + + returnM (co_fn <$> unLoc (foldl mkHsApp 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 - = 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 ~(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' @@ -628,32 +670,32 @@ checkArgsCtxt fun args expected_res_ty actual_res_ty tidy_env | len_exp_args > len_act_args = wrongArgsCtxt "too many" fun args | otherwise = appCtxt fun args in - returnNF_Tc (env2, message) + 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 split_fun_ty fun_ty 0 - = returnTc ([], fun_ty) + = returnM ([], 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) + unifyFunTy fun_ty `thenM` \ (arg_ty, res_ty) -> + split_fun_ty res_ty (n-1) `thenM` \ (arg_tys, final_res_ty) -> + returnM (arg_ty:arg_tys, final_res_ty) \end{code} \begin{code} -tcArg :: RenamedHsExpr -- The function (for error messages) - -> (RenamedHsExpr, TcSigmaType, Int) -- Actual argument and expected arg type - -> TcM (TcExpr, LIE) -- Resulting argument and LIE +tcArg :: LHsExpr Name -- The function (for error messages) + -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type + -> TcM (LHsExpr TcId) -- Resulting argument tcArg the_fun (arg, expected_arg_ty, arg_no) - = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $ - tcExpr arg expected_arg_ty + = addErrCtxt (funAppCtxt the_fun arg arg_no) $ + tcCheckSigma arg expected_arg_ty \end{code} @@ -663,76 +705,140 @@ tcArg the_fun (arg, expected_arg_ty, arg_no) %* * %************************************************************************ -\begin{code} -tcId :: Name -> NF_TcM (TcExpr, LIE, TcType) -tcId name -- Look up the Id and instantiate its type - = tcLookupId name `thenNF_Tc` \ id -> - tcInstId id -\end{code} - -Typecheck expression which in most cases will be an Id. +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} -tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, LIE, TcType) -tcExpr_id (HsVar name) = tcId name -tcExpr_id expr = newTyVarTy openTypeKind `thenNF_Tc` \ id_ty -> - tcMonoExpr expr id_ty `thenTc` \ (expr', lie_id) -> - returnTc (expr', lie_id, id_ty) -\end{code} - - -%************************************************************************ -%* * -\subsection{@tcDoStmts@ typechecks a {\em list} of do statements} -%* * -%************************************************************************ +tcId :: Name -> TcM (HsExpr TcId, 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" + 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 -\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 $ - - -- 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` \ elt_ty -> - returnNF_Tc (mkTyConTy listTyCon, (mkListTy, elt_ty)) - - _ -> newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenNF_Tc` \ m_ty -> - newTyVarTy liftedTypeKind `thenNF_Tc` \ elt_ty -> - unifyTauTy res_ty (mkAppTy m_ty elt_ty) `thenTc_` - returnNF_Tc (m_ty, (mkAppTy m_ty, elt_ty)) - ) `thenNF_Tc` \ (tc_ty, m_ty) -> - - tcStmts (DoCtxt do_or_lc) m_ty stmts `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 returnMName `thenNF_Tc` \ return_sel_id -> - tcLookupGlobalId thenMName `thenNF_Tc` \ then_sel_id -> - tcLookupGlobalId failMName `thenNF_Tc` \ fail_sel_id -> - newMethod DoOrigin return_sel_id [tc_ty] `thenNF_Tc` \ return_inst -> - newMethod DoOrigin then_sel_id [tc_ty] `thenNF_Tc` \ then_inst -> - newMethod DoOrigin fail_sel_id [tc_ty] `thenNF_Tc` \ fail_inst -> - let - monad_lie = mkLIE [return_inst, then_inst, fail_inst] - in - returnTc (HsDoOut do_or_lc stmts' - (instToId return_inst) (instToId then_inst) (instToId fail_inst) - res_ty src_loc, - stmts_lie `plusLIE` monad_lie) +#ifndef GHCI + 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_` + + -- 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 + -> -- E.g. \x -> [| h x |] + -- We must behave as if the reference to x was + + -- h $(lift x) + -- We use 'x' itself as the splice proxy, used by + -- the desugarer to stitch it all back together. + -- If 'x' occurs many times we may get many identical + -- bindings of the same splice proxy, but that doesn't + -- matter, although it's a mite untidy. + let + id_ty = idType id + in + checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_` + -- If x is polymorphic, its occurrence sites might + -- have different instantiations, so we can't use plain + -- 'x' as the splice proxy name. I don't know how to + -- solve this, and it's probably unimportant, so I'm + -- just going to flag an error for now + + setLIEVar lie_var ( + newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift -> + -- Put the 'lift' constraint into the right LIE + + -- Update the pending splices + readMutVar ps_var `thenM` \ ps -> + writeMutVar ps_var ((name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_` + + returnM (HsVar id, id_ty)) + + other -> + checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_` + loop (HsVar id) (idType id) +#endif /* GHCI */ + + loop (HsVar fun_id) fun_ty + | want_method_inst fun_ty + = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) -> + newMethodWithGivenTy orig fun_id + (mkTyVarTys tyvars) theta tau `thenM` \ meth_id -> + loop (HsVar meth_id) tau + + loop fun fun_ty + | isSigmaTy fun_ty + = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) -> + loop (inst_fn <$> fun) tau + + | otherwise + = returnM (fun, 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) + + + -- We treat data constructors differently, because we have to generate + -- constraints for their silly theta, which no longer appears in + -- 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_` + getSrcSpanM `thenM` \ loc -> + returnM (unLoc (mkHsDictApp (mkHsTyApp (L loc (HsVar (dataConWrapId data_con))) ty_args) + (map instToId ex_dicts)), + mkFunTys arg_tys result_ty) + -- ToDo: nasty loc/unloc stuff here + + orig = OccurrenceOf name \end{code} - %************************************************************************ %* * \subsection{Record bindings} @@ -760,17 +866,17 @@ 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 - do_bind (field_lbl_name, rhs, pun_flag) - = tcLookupGlobalId field_lbl_name `thenNF_Tc` \ sel_id -> + do_bind (L loc field_lbl_name, rhs) + = addErrCtxt (fieldCtxt field_lbl_name) $ + tcLookupId field_lbl_name `thenM` \ sel_id -> let field_lbl = recordSelectorFieldLabel sel_id field_ty = substTy tenv (fieldLabelType field_lbl) @@ -783,59 +889,69 @@ 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 `thenTc` \ (rhs', lie) -> + tcCheckSigma rhs field_ty `thenM` \ rhs' -> - returnTc ((sel_id, rhs', pun_flag), lie) + returnM (L loc sel_id, rhs') 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) -missingFields rbinds data_con - | null field_labels = ([], []) -- Not declared as a record; - -- But C{} is still valid - | otherwise - = (missing_strict_fields, other_missing_fields) +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_` + + doptM Opt_WarnMissingFields `thenM` \ warn -> + checkM (not (warn && notNull missing_ns_fields)) + (warnTc True (missingFields data_con missing_ns_fields)) + where - missing_strict_fields + missing_s_fields = [ fl | (fl, str) <- field_info, isMarkedStrict str, not (fieldLabelName fl `elem` field_names_used) ] - other_missing_fields + missing_ns_fields = [ fl | (fl, str) <- field_info, not (isMarkedStrict str), not (fieldLabelName fl `elem` field_names_used) ] - field_names_used = [ field_name | (field_name, _, _) <- rbinds ] + field_names_used = recBindFields rbinds field_labels = dataConFieldLabels data_con field_info = zipEqual "missingFields" field_labels - (dropList ex_theta (dataConStrictMarks data_con)) - -- The 'drop' is because dataConStrictMarks - -- includes the existential dictionaries - (_, _, _, ex_theta, _, _) = dataConSig data_con + 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} @@ -848,16 +964,10 @@ 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 -> - newDicts (LitLitOrigin (_UNPK_ s)) - [mkClassPred cCallableClass [res_ty]] `thenNF_Tc` \ dicts -> - returnTc (HsLit (HsLitLit s res_ty), mkLIE 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} @@ -867,60 +977,48 @@ tcLit lit res_ty %* * %************************************************************************ -Mini-utils: - 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) - exprCtxt expr = hang (ptext SLIT("In the expression:")) 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 @@ -928,13 +1026,33 @@ 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 -> FieldLabel -> 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 -> FieldLabel -> 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}