X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=7e5f0337bf621a4ff4f3fc07558bd68de2cb447e;hb=c5a65b1704212e3f4354841ff480c660a3b51fb6;hp=48c62a049c35e66433cf52999a33a416c32c69e3;hpb=2a74e354528a397235b42af49a99844c1712e8c4;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 48c62a0..cf94f27 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -1,172 +1,184 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcExpr]{Typecheck an expression} \begin{code} -#include "HsVersions.h" - -module TcExpr ( tcExpr, tcStmt, tcId ) where - -IMP_Ubiq() +module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where -import HsSyn ( HsExpr(..), Stmt(..), DoOrListComp(..), - HsBinds(..), MonoBinds(..), - SYN_IE(RecFlag), nonRecursive, - ArithSeqInfo(..), HsLit(..), Sig, GRHSsAndBinds, - Match, Fake, InPat, OutPat, HsType, Fixity, - pprParendExpr, failureFreePat, collectPatBinders ) -import RnHsSyn ( SYN_IE(RenamedHsExpr), - SYN_IE(RenamedStmt), SYN_IE(RenamedRecordBinds) - ) -import TcHsSyn ( SYN_IE(TcExpr), SYN_IE(TcStmt), - TcIdOcc(..), SYN_IE(TcRecordBinds), - mkHsTyApp - ) +#include "HsVersions.h" -import TcMonad -import Inst ( Inst, InstOrigin(..), OverloadedLit(..), - SYN_IE(LIE), emptyLIE, plusLIE, plusLIEs, newOverloadedLit, - newMethod, newMethodWithGivenTy, newDicts ) -import TcBinds ( tcBindsAndThen, checkSigTyVars ) -import TcEnv ( tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey, - tcLookupGlobalValueByKey, newMonoIds, tcGetGlobalTyVars, - tcExtendGlobalTyVars, tcLookupGlobalValueMaybe +#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(..), + newOverloadedLit, newMethodFromName, newIPDict, + newDicts, newMethodWithGivenTy, + instToId, tcInstCall, tcInstDataCon ) -import SpecEnv ( SpecEnv ) -import TcMatches ( tcMatchesCase, tcMatch ) -import TcMonoType ( tcHsType ) -import TcPat ( tcPat ) -import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 ) -import TcType ( SYN_IE(TcType), TcMaybe(..), - tcInstId, tcInstType, tcInstSigTcType, tcInstTyVars, - tcInstSigType, tcInstTcType, tcInstTheta, tcSplitRhoTy, - newTyVarTy, newTyVarTys, zonkTcTyVars, zonkTcType ) -import TcKind ( TcKind ) - -import Class ( SYN_IE(Class) ) -import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType ) -import Id ( idType, dataConFieldLabels, dataConSig, recordSelectorFieldLabel, - isRecordSelector, - SYN_IE(Id), GenId +import TcBinds ( tcBindsAndThen ) +import TcEnv ( tcLookup, tcLookupId, checkProcLevel, + tcLookupDataCon, tcLookupGlobalId ) -import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind ) -import Name ( Name{-instance Eq-} ) -import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys, mkRhoTy, - getTyVar_maybe, getFunTy_maybe, instantiateTy, applyTyCon, - splitForAllTy, splitRhoTy, splitSigmaTy, splitFunTy, - isTauTy, mkFunTys, tyVarsOfType, tyVarsOfTypes, getForAllTy_maybe, - getAppDataTyCon, maybeAppDataTyCon +import TcArrows ( tcProc ) +import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) ) +import TcHsType ( tcHsSigType, UserTypeCtxt(..) ) +import TcPat ( badFieldCon ) +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 TyVar ( GenTyVar, SYN_IE(TyVarSet), unionTyVarSets, elementOfTyVarSet, mkTyVarSet ) -import TysPrim ( intPrimTy, charPrimTy, doublePrimTy, - floatPrimTy, addrPrimTy, realWorldTy +import Kind ( openTypeKind, liftedTypeKind, argTypeKind ) + +import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon ) +import Id ( idType, recordSelectorFieldLabel, isRecordSelector ) +import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId ) +import Name ( Name ) +import TyCon ( TyCon, tyConTyVars, tyConTheta, tyConDataCons ) +import Subst ( mkTopTyVarSubst, substTheta, substTy ) +import VarSet ( emptyVarSet, elemVarSet ) +import TysWiredIn ( boolTy ) +import PrelNames ( enumFromName, enumFromThenName, + enumFromToName, enumFromThenToName, + enumFromToPName, enumFromThenToPName ) -import TysWiredIn ( addrTy, - boolTy, charTy, stringTy, mkListTy, - mkTupleTy, mkPrimIoTy, stDataCon - ) -import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy ) -import Unique ( Unique, cCallableClassKey, cReturnableClassKey, - enumFromClassOpKey, enumFromThenClassOpKey, - enumFromToClassOpKey, enumFromThenToClassOpKey, - thenMClassOpKey, zeroClassOpKey, returnMClassOpKey - ) -import Outputable ( speakNth, interpp'SP, Outputable(..) ) -import PprType ( GenType, GenTyVar ) -- Instances -import Maybes ( maybeToBool ) -import Pretty import ListSetOps ( minusList ) +import CmdLineOpts +import HscTypes ( TyThing(..) ) +import SrcLoc ( Located(..), unLoc, getLoc ) import Util -\end{code} +import Outputable +import FastString -\begin{code} -tcExpr :: RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s) +#ifdef DEBUG +import TyCon ( isAlgTyCon ) +#endif \end{code} %************************************************************************ %* * -\subsection{The TAUT rules for variables} +\subsection{Main wrappers} %* * %************************************************************************ \begin{code} -tcExpr (HsVar name) - = tcId name `thenNF_Tc` \ (expr', lie, res_ty) -> +-- 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} - -- 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 res_ty) - (lurkingRank2Err name res_ty) `thenTc_` +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. - returnTc (expr', lie, res_ty) +\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{Literals} +\subsection{The TAUT rules for variables}TcExpr %* * %************************************************************************ -Overloaded literals. - \begin{code} -tcExpr (HsLit (HsInt i)) - = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty -> - - newOverloadedLit (LiteralOrigin (HsInt i)) - (OverloadedIntegral i) - ty `thenNF_Tc` \ (lie, over_lit_id) -> - - returnTc (HsVar over_lit_id, lie, ty) - -tcExpr (HsLit (HsFrac f)) - = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty -> - - newOverloadedLit (LiteralOrigin (HsFrac f)) - (OverloadedFractional f) - ty `thenNF_Tc` \ (lie, over_lit_id) -> - - returnTc (HsVar over_lit_id, lie, ty) - -tcExpr (HsLit lit@(HsLitLit s)) - = tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass -> - newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty -> - newDicts (LitLitOrigin (_UNPK_ s)) - [(cCallableClass, ty)] `thenNF_Tc` \ (dicts, _) -> - returnTc (HsLitOut lit ty, dicts, ty) +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 + = addSrcSpan 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 + = tcId name `thenM` \ (expr', id_ty) -> + tcSubExp res_ty id_ty `thenM` \ co_fn -> + 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.) + 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} -Primitive literals: -\begin{code} -tcExpr (HsLit lit@(HsCharPrim c)) - = returnTc (HsLitOut lit charPrimTy, emptyLIE, charPrimTy) - -tcExpr (HsLit lit@(HsStringPrim s)) - = returnTc (HsLitOut lit addrPrimTy, emptyLIE, addrPrimTy) - -tcExpr (HsLit lit@(HsIntPrim i)) - = returnTc (HsLitOut lit intPrimTy, emptyLIE, intPrimTy) - -tcExpr (HsLit lit@(HsFloatPrim f)) - = returnTc (HsLitOut lit floatPrimTy, emptyLIE, floatPrimTy) - -tcExpr (HsLit lit@(HsDoublePrim d)) - = returnTc (HsLitOut lit doublePrimTy, emptyLIE, doublePrimTy) -\end{code} - -Unoverloaded literals: +%************************************************************************ +%* * +\subsection{Expressions type signatures} +%* * +%************************************************************************ \begin{code} -tcExpr (HsLit lit@(HsChar c)) - = returnTc (HsLitOut lit charTy, emptyLIE, charTy) - -tcExpr (HsLit lit@(HsString str)) - = returnTc (HsLitOut lit stringTy, emptyLIE, stringTy) +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} + %************************************************************************ %* * \subsection{Other expression forms} @@ -174,26 +186,30 @@ tcExpr (HsLit lit@(HsString str)) %************************************************************************ \begin{code} -tcExpr (HsPar expr) -- preserve parens so printing needn't guess where they go - = tcExpr expr - -tcExpr (NegApp expr neg) = tcExpr (HsApp neg expr) - -tcExpr (HsLam match) - = tcMatch match `thenTc` \ (match',lie,ty) -> - returnTc (HsLam match', lie, ty) - -tcExpr (HsApp e1 e2) = accum e1 [e2] - where - accum (HsApp e1 e2) args = accum e1 (e2:args) - accum fun args - = tcApp fun args `thenTc` \ (fun', args', lie, res_ty) -> - returnTc (foldl HsApp fun' args', lie, res_ty) - --- equivalent to (op e1) e2: -tcExpr (OpApp arg1 op fix arg2) - = tcApp op [arg1,arg2] `thenTc` \ (op', [arg1', arg2'], lie, res_ty) -> - returnTc (OpApp arg1' op' fix arg2', lie, 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') + +tc_expr (HsLit lit) res_ty = tcLit lit res_ty + +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 + +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 @@ -207,167 +223,148 @@ a type error will occur if they aren't. -- or just -- op e -tcExpr in_expr@(SectionL arg op) - = tcApp op [arg] `thenTc` \ (op', [arg'], lie, res_ty) -> - - -- 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! - newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 -> - newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 -> - tcAddErrCtxt (sectionLAppCtxt in_expr) $ - unifyTauTy (mkFunTy ty1 ty2) res_ty `thenTc_` - - returnTc (SectionL arg' op', lie, res_ty) +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 -tcExpr in_expr@(SectionR op expr) - = tcExpr op `thenTc` \ (op', lie1, op_ty) -> - tcExpr expr `thenTc` \ (expr',lie2, expr_ty) -> - - newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 -> - newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 -> - tcAddErrCtxt (sectionRAppCtxt in_expr) $ - unifyTauTy (mkFunTys [ty1, expr_ty] ty2) op_ty `thenTc_` +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') - returnTc (SectionR op' expr', lie1 `plusLIE` lie2, mkFunTy ty1 ty2) -\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} -tcExpr (CCall lbl args may_gc is_asm ignored_fake_result_ty) - = -- Get the callable and returnable classes. - tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass -> - tcLookupClassByKey cReturnableClassKey `thenNF_Tc` \ cReturnableClass -> - - let - new_arg_dict (arg, arg_ty) - = newDicts (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 - - -- Arguments - tcExprs args `thenTc` \ (args', args_lie, arg_tys) -> - - -- The argument types can be unboxed or boxed; the result - -- type must, however, be boxed since it's an argument to the PrimIO - -- type constructor. - newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ result_ty -> - - -- Construct the extra insts, which encode the - -- constraints on the argument and result types. - mapNF_Tc new_arg_dict (zipEqual "tcExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s -> - newDicts result_origin [(cReturnableClass, result_ty)] `thenNF_Tc` \ (ccres_dict, _) -> +-- equivalent to (op e1) e2: - returnTc (HsApp (HsVar (RealId stDataCon) `TyApp` [realWorldTy, result_ty]) - (CCall lbl args' may_gc is_asm result_ty), - -- do the wrapping in the newtype constructor here - foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie, - mkPrimIoTy result_ty) +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} -tcExpr (HsSCC label expr) - = tcExpr expr `thenTc` \ (expr', lie, expr_ty) -> - -- No unification. Give SCC the type of expr - returnTc (HsSCC label expr', lie, expr_ty) - -tcExpr (HsLet binds expr) +tc_expr (HsLet binds (L loc expr)) res_ty = tcBindsAndThen - combiner + glue binds -- Bindings to check - (tc_expr expr) `thenTc` \ ((expr', ty), lie) -> - returnTc (expr', lie, ty) + (tc_expr expr res_ty) where - tc_expr expr = tcExpr expr `thenTc` \ (expr', lie, ty) -> - returnTc ((expr',ty), lie) - combiner is_rec bind (expr, ty) = (HsLet (MonoBind bind [] is_rec) expr, ty) + glue bind expr = HsLet [bind] (L loc expr) -tcExpr in_expr@(HsCase expr matches src_loc) - = tcAddSrcLoc src_loc $ - tcExpr expr `thenTc` \ (expr',lie1,expr_ty) -> - newTyVarTy mkTypeKind `thenNF_Tc` \ result_ty -> +tc_expr in_expr@(HsCase scrut matches) res_ty + = addErrCtxt (caseCtxt in_expr) $ - tcAddErrCtxt (caseCtxt in_expr) $ - tcMatchesCase (mkFunTy expr_ty result_ty) matches - `thenTc` \ (matches',lie2) -> + -- 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 - returnTc (HsCase expr' matches' src_loc, plusLIE lie1 lie2, result_ty) + tcMatchesCase match_ctxt matches res_ty `thenM` \ (scrut_ty, matches') -> -tcExpr (HsIf pred b1 b2 src_loc) - = tcAddSrcLoc src_loc $ - tcExpr pred `thenTc` \ (pred',lie1,predTy) -> + addErrCtxt (caseScrutCtxt scrut) ( + tcCheckRho scrut scrut_ty + ) `thenM` \ scrut' -> - tcAddErrCtxt (predCtxt pred) ( - unifyTauTy boolTy predTy - ) `thenTc_` + 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 - tcExpr b1 `thenTc` \ (b1',lie2,result_ty) -> - tcExpr b2 `thenTc` \ (b2',lie3,b2Ty) -> +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 - tcAddErrCtxt (branchCtxt b1 b2) $ - unifyTauTy result_ty b2Ty `thenTc_` +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) - returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3), result_ty) +tc_expr (HsProc pat cmd) res_ty + = tcProc pat cmd res_ty `thenM` \ (pat', cmd') -> + returnM (HsProc pat' cmd') \end{code} -\begin{code} -tcExpr expr@(HsDo do_or_lc stmts src_loc) - = tcDoStmts do_or_lc stmts src_loc -\end{code} +%************************************************************************ +%* * + Record construction and update +%* * +%************************************************************************ \begin{code} -tcExpr in_expr@(ExplicitList exprs) -- Non-empty list - = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ elt_ty -> - mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) -> - returnTc (ExplicitListOut elt_ty exprs', plusLIEs lies, mkListTy elt_ty) - where - tc_elt elt_ty expr - = tcAddErrCtxt (listCtxt expr) $ - tcExpr expr `thenTc` \ (expr', lie, expr_ty) -> - unifyTauTy elt_ty expr_ty `thenTc_` - returnTc (expr', lie) - -tcExpr (ExplicitTuple exprs) - = tcExprs exprs `thenTc` \ (exprs', lie, tys) -> - returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys) - -tcExpr (RecordCon (HsVar con) rbinds) - = tcId con `thenNF_Tc` \ (con_expr, con_lie, con_tau) -> +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) = splitFunTy con_tau + (_, record_ty) = tcSplitFunTys con_tau + (tycon, ty_args) = tcSplitTyConApp record_ty in - -- Con is syntactically constrained to be a data constructor - ASSERT( maybeToBool (maybeAppDataTyCon record_ty ) ) + ASSERT( isAlgTyCon tycon ) + zapExpectedTo res_ty record_ty `thenM_` -- Check that the record bindings match the constructor - tcLookupGlobalValue con `thenNF_Tc` \ con_id -> + -- con_name is syntactically constrained to be a data constructor + tcLookupDataCon con_name `thenM` \ data_con -> let - bad_fields = badFields rbinds con_id + bad_fields = badFields rbinds data_con in - checkTc (null bad_fields) (badFieldsCon con bad_fields) `thenTc_` + 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 - -- (Do this after checkRecordFields in case there's a field that - -- doesn't match the constructor.) - tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) -> - - returnTc (RecordCon con_expr rbinds', con_lie `plusLIE` rbinds_lie, record_ty) + tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' -> + + -- Check for missing fields + checkMissingFields data_con rbinds `thenM_` + 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: @@ -395,40 +392,53 @@ tcExpr (RecordCon (HsVar con) rbinds) -- -- All this is done in STEP 4 below. -tcExpr (RecordUpd record_expr rbinds) - = tcAddErrCtxt recordUpdCtxt $ +tc_expr expr@(RecordUpd record_expr rbinds) res_ty + = addErrCtxt (recordUpdCtxt expr) $ - -- STEP 1 - -- Figure out the tycon and data cons from the first field name - ASSERT( not (null rbinds) ) + -- STEP 0 + -- Check that the field names are really field names + ASSERT( notNull rbinds ) let - ((first_field_name, _, _) : rest) = rbinds + field_names = map fst rbinds + in + mappM (tcLookupGlobalId.unLoc) field_names `thenM` \ sel_ids -> + -- The renamer has already checked that they + -- are all in scope + let + 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 - tcLookupGlobalValueMaybe first_field_name `thenNF_Tc` \ maybe_sel_id -> - (case maybe_sel_id of - Just sel_id | isRecordSelector sel_id -> returnTc sel_id - other -> failTc (notSelector first_field_name) - ) `thenTc` \ sel_id -> + 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 - (_, tau) = splitForAllTy (idType sel_id) - Just (data_ty, _) = getFunTy_maybe tau -- Must succeed since sel_id is a selector - (tycon, _, data_cons) = getAppDataTyCon data_ty - (con_tyvars, theta, _, _, _, _) = dataConSig (head data_cons) + -- It's OK to use the non-tc splitters here (for a selector) + 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, result_inst_env) -> + tcInstTyVars VanillaTv tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) -> -- STEP 2 - -- Check for bad fields + -- 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. -- (Do this after checking for bad fields in case there's a field that -- doesn't match the constructor.) let - result_record_ty = applyTyCon tycon result_inst_tys + result_record_ty = mkTyConApp tycon result_inst_tys in - tcRecordBinds result_record_ty 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 @@ -437,7 +447,7 @@ tcExpr (RecordUpd record_expr rbinds) -- 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 | (RealId 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 @@ -449,136 +459,141 @@ tcExpr (RecordUpd record_expr rbinds) common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls) mk_inst_ty (tyvar, result_inst_ty) - | tyvar `elementOfTyVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type - | otherwise = newTyVarTy mkBoxedTypeKind -- 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 - tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) -> - unifyTauTy (applyTyCon tycon inst_tys) record_ty `thenTc_` - + let + record_ty = mkTyConApp tycon inst_tys + in + 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 = zipEqual "tcExpr:RecordUpd" tyvars result_inst_tys + theta' = substTheta inst_env (tyConTheta tycon) in - tcInstTheta inst_env theta `thenNF_Tc` \ theta' -> - newDicts 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, - result_record_ty) - - -tcExpr (ArithSeqIn seq@(From expr)) - = tcExpr expr `thenTc` \ (expr', lie1, ty) -> - - tcLookupGlobalValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - (RealId sel_id) [ty] `thenNF_Tc` \ (lie2, enum_from_id) -> - - returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'), - lie1 `plusLIE` lie2, - mkListTy ty) - -tcExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) - = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) -> - tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) -> - - tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyTauTyList [ty1, ty2] `thenTc_` - - tcLookupGlobalValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_then_id) -> - - returnTc (ArithSeqOut (HsVar enum_from_then_id) - (FromThen expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` lie3, - mkListTy ty1) - -tcExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) - = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) -> - tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) -> - - tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyTauTyList [ty1,ty2] `thenTc_` + returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds') +\end{code} - tcLookupGlobalValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_to_id) -> - returnTc (ArithSeqOut (HsVar enum_from_to_id) - (FromTo expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` lie3, - mkListTy ty1) +%************************************************************************ +%* * + Arithmetic sequences e.g. [a,b..] + and their parallel-array counterparts e.g. [: a,b.. :] + +%* * +%************************************************************************ -tcExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) - = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) -> - tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) -> - tcExpr expr3 `thenTc` \ (expr3',lie3,ty3) -> +\begin{code} +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} - tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyTauTyList [ty1,ty2,ty3] `thenTc_` - tcLookupGlobalValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - (RealId sel_id) [ty1] `thenNF_Tc` \ (lie4, eft_id) -> +%************************************************************************ +%* * + Template Haskell +%* * +%************************************************************************ - returnTc (ArithSeqOut (HsVar eft_id) - (FromThenTo expr1' expr2' expr3'), - lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4, - mkListTy ty1) +\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} + %************************************************************************ %* * -\subsection{Expressions type signatures} + Catch-all %* * %************************************************************************ \begin{code} -tcExpr in_expr@(ExprWithTySig expr poly_ty) - = tcExpr expr `thenTc` \ (texpr, lie, tau_ty) -> - tcHsType poly_ty `thenTc` \ sigma_sig -> - - -- Check the tau-type part - tcSetErrCtxt (exprSigCtxt in_expr) $ - tcInstSigType sigma_sig `thenNF_Tc` \ sigma_sig' -> - let - (sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig' - in - unifyTauTy sig_tau' tau_ty `thenTc_` - - -- Check the type variables of the signature - checkSigTyVars sig_tyvars' sig_tau' `thenTc_` - - -- Check overloading constraints - newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (sig_dicts, _) -> - tcSimplifyAndCheck - (mkTyVarSet sig_tyvars') - sig_dicts lie `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, except for any default - -- resolution it may have done, which is recorded in the - -- substitution. - returnTc (texpr, lie, tau_ty) +tc_expr other _ = pprPanic "tcMonoExpr" (ppr other) \end{code} + %************************************************************************ %* * \subsection{@tcApp@ typchecks an application} @@ -586,306 +601,242 @@ tcExpr in_expr@(ExprWithTySig expr poly_ty) %************************************************************************ \begin{code} -tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args - -> TcM s (TcExpr s, [TcExpr s], -- Translated fun and args - LIE s, - TcType s) -- Type of the application -tcApp fun args +tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args + -> Expected TcRhoType -- Expected result type of application + -> TcM (HsExpr TcId) -- Translated fun and args + +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 - -- In the HsVar case we go straight to tcId to avoid hitting the - -- rank-2 check, which we check later here anyway - (case fun of - HsVar name -> tcId name `thenNF_Tc` \ stuff -> returnTc stuff - other -> tcExpr fun - ) `thenTc` \ (fun', lie_fun, fun_ty) -> + tcInferRho fun `thenM` \ (fun', fun_ty) -> + + addErrCtxt (wrongArgsCtxt "too many" fun args) ( + traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_` + split_fun_ty fun_ty (length args) + ) `thenM` \ (expected_arg_tys, actual_result_ty) -> + + -- Unify with expected result before (was: after) type-checking the args + -- so that the info from res_ty (was: args) percolates to args (was actual_result_ty). + -- This is when we might detect a too-few args situation. + -- (One can think of cases when the opposite order would give + -- a better error message.) + -- [March 2003: I'm experimenting with putting this first. Here's an + -- example where it actually makes a real difference + -- class C t a b | t a -> b + -- instance C Char a Bool + -- + -- data P t a = forall b. (C t a b) => MkP b + -- data Q t = MkQ (forall a. P t a) + + -- f1, f2 :: Q Char; + -- f1 = MkQ (MkP True) + -- f2 = MkQ (MkP True :: forall a. P Char a) + -- + -- With the change, f1 will type-check, because the 'Char' info from + -- the signature is propagated into MkQ's argument. With the check + -- in the other order, the extra signature in f2 is reqd.] - tcApp_help fun 1 fun_ty args `thenTc` \ (args', lie_args, res_ty) -> + addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) + (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn -> - -- 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 res_ty) - (lurkingRank2Err fun fun_ty) `thenTc_` + -- Now typecheck the args + mappM (tcArg fun) + (zip3 args expected_arg_tys [1..]) `thenM` \ args' -> - returnTc (fun', args', lie_fun `plusLIE` lie_args, res_ty) + returnM (co_fn <$> unLoc (foldl mkHsApp fun' args')) -tcApp_help :: RenamedHsExpr -> Int -- Function and arg position, used in error message(s) - -> TcType s -- The type of the function - -> [RenamedHsExpr] -- Arguments - -> TcM s ([TcExpr s], -- Typechecked args - LIE s, - TcType s) -- Result type of the application +-- If an error happens we try to figure out whether the +-- function has been given too many or too few arguments, +-- 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' + (exp_args, _) = tcSplitFunTys exp_ty'' + (act_args, _) = tcSplitFunTys act_ty'' -tcApp_help orig_fun arg_no fun_ty [] - = returnTc ([], emptyLIE, fun_ty) + len_act_args = length act_args + len_exp_args = length exp_args -tcApp_help orig_fun arg_no fun_ty all_args@(arg:args) - = -- Expect the function to have type A->B - tcAddErrCtxt (tooManyArgsCtxt orig_fun) ( - unifyFunTy fun_ty - ) `thenTc` \ (expected_arg_ty, result_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) - -- Type check the argument - tcAddErrCtxt (funAppCtxt orig_fun arg_no arg) ( - tcArg expected_arg_ty arg - ) `thenTc` \ (arg', lie_arg) -> - -- Do the other args - tcApp_help orig_fun (arg_no+1) result_ty args `thenTc` \ (args', lie_args, res_ty) -> +split_fun_ty :: TcRhoType -- The type of the function + -> Int -- Number of arguments + -> TcM ([TcType], -- Function argument types + TcType) -- Function result types - -- Done - returnTc (arg':args', lie_arg `plusLIE` lie_args, res_ty) +split_fun_ty fun_ty 0 + = returnM ([], fun_ty) +split_fun_ty fun_ty n + = -- Expect the function to have type A->B + 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 :: TcType s -- Expected arg type - -> RenamedHsExpr -- Actual argument - -> TcM s (TcExpr s, LIE s) -- Resulting argument and LIE - -tcArg expected_arg_ty arg - | not (maybeToBool (getForAllTy_maybe expected_arg_ty)) - = -- The ordinary, non-rank-2 polymorphic case - tcExpr arg `thenTc` \ (arg', lie_arg, actual_arg_ty) -> - unifyTauTy expected_arg_ty actual_arg_ty `thenTc_` - returnTc (arg', lie_arg) - - | otherwise - = -- Ha! The argument type of the function is a for-all type, - -- An example of rank-2 polymorphism. - - -- No need to instantiate the argument type... it's must be the result - -- of instantiating a function involving rank-2 polymorphism, so there - -- isn't any danger of using the same tyvars twice - -- The argument type shouldn't be overloaded type (hence ASSERT) - - -- To ensure that the forall'd type variables don't get unified with each - -- other or any other types, we make fresh *signature* type variables - -- and unify them with the tyvars. - tcInstSigTcType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_rho) -> - let - (sig_theta, sig_tau) = splitRhoTy sig_rho - in - ASSERT( null sig_theta ) -- And expected_tyvars are all DontBind things - - -- Type-check the arg and unify with expected type - tcExpr arg `thenTc` \ (arg', lie_arg, actual_arg_ty) -> - unifyTauTy sig_tau actual_arg_ty `thenTc_` - - -- Check that the arg_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. - - tcAddErrCtxt (rank2ArgCtxt arg expected_arg_ty) ( - tcExtendGlobalTyVars (tyVarsOfType expected_arg_ty) ( - checkSigTyVars sig_tyvars sig_tau - ) `thenTc_` - - -- Check that there's no overloading involved - -- Even if there isn't, there may be some Insts which mention the expected_tyvars, - -- but which, on simplification, don't actually need a dictionary involving - -- the tyvar. So we have to do a proper simplification right here. - tcSimplifyRank2 (mkTyVarSet sig_tyvars) - lie_arg `thenTc` \ (free_insts, inst_binds) -> - - -- 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. - returnTc (TyLam sig_tyvars (HsLet (mk_binds inst_binds) arg'), free_insts) - ) - where - mk_binds inst_binds = MonoBind inst_binds [] nonRecursive +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) + = addErrCtxt (funAppCtxt the_fun arg arg_no) $ + tcCheckSigma arg expected_arg_ty \end{code} + %************************************************************************ %* * \subsection{@tcId@ typchecks an identifier occurrence} %* * %************************************************************************ -\begin{code} -tcId :: Name -> NF_TcM s (TcExpr s, LIE s, TcType s) - -tcId name - = -- Look up the Id and instantiate its type - tcLookupLocalValue name `thenNF_Tc` \ maybe_local -> - - case maybe_local of - Just tc_id -> instantiate_it (TcId tc_id) (idType tc_id) - - Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id -> - tcInstType [] (idType id) `thenNF_Tc` \ inst_ty -> - let - (tyvars, rho) = splitForAllTy inst_ty - in - instantiate_it2 (RealId id) tyvars rho - - 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 tc_id_occ ty - = tcInstTcType ty `thenNF_Tc` \ (tyvars, rho) -> - instantiate_it2 tc_id_occ tyvars rho - - instantiate_it2 tc_id_occ tyvars rho - = tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) -> - if null theta then -- Is it overloaded? - returnNF_Tc (mkHsTyApp (HsVar tc_id_occ) arg_tys, emptyLIE, tau) - else - -- Yes, it's overloaded - newMethodWithGivenTy (OccurrenceOf tc_id_occ) - tc_id_occ arg_tys rho `thenNF_Tc` \ (lie1, meth_id) -> - instantiate_it meth_id 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} -%* * -%************************************************************************ +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} -tcDoStmts do_or_lc stmts src_loc - = -- get the Monad and MonadZero classes - -- create type consisting of a fresh monad tyvar - ASSERT( not (null stmts) ) - tcAddSrcLoc src_loc $ - newTyVarTy (mkArrowKind mkBoxedTypeKind mkBoxedTypeKind) `thenNF_Tc` \ m -> - - let - tc_stmts [] = returnTc (([], error "tc_stmts"), emptyLIE) - tc_stmts (stmt:stmts) = tcStmt tcExpr do_or_lc (mkAppTy m) combine_stmts stmt $ - tc_stmts stmts - - combine_stmts stmt@(ReturnStmt _) (Just ty) ([], _) = ([stmt], ty) - combine_stmts stmt@(ExprStmt e _) (Just ty) ([], _) = ([stmt], ty) - combine_stmts stmt _ ([], _) = panic "Bad last stmt tcDoStmts" - combine_stmts stmt _ (stmts, ty) = (stmt:stmts, ty) - in - tc_stmts stmts `thenTc` \ ((stmts', result_ty), final_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. - -- - tcLookupGlobalValueByKey returnMClassOpKey `thenNF_Tc` \ return_sel_id -> - tcLookupGlobalValueByKey thenMClassOpKey `thenNF_Tc` \ then_sel_id -> - tcLookupGlobalValueByKey zeroClassOpKey `thenNF_Tc` \ zero_sel_id -> - newMethod DoOrigin - (RealId return_sel_id) [m] `thenNF_Tc` \ (return_lie, return_id) -> - newMethod DoOrigin - (RealId then_sel_id) [m] `thenNF_Tc` \ (then_lie, then_id) -> - newMethod DoOrigin - (RealId zero_sel_id) [m] `thenNF_Tc` \ (zero_lie, zero_id) -> - let - monad_lie = then_lie `plusLIE` return_lie `plusLIE` perhaps_zero_lie - perhaps_zero_lie | all failure_free stmts' = emptyLIE - | otherwise = zero_lie - - failure_free (BindStmt pat _ _) = failureFreePat pat - failure_free (GuardStmt _ _) = False - failure_free other_stmt = True - in - returnTc (HsDoOut do_or_lc stmts' return_id then_id zero_id result_ty src_loc, - final_lie `plusLIE` monad_lie, - result_ty) -\end{code} +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} -tcStmt :: (RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s)) -- This is tcExpr - -- The sole, disgusting, reason for this parameter - -- is to get the effect of polymorphic recursion - -- ToDo: rm when booting with Haskell 1.3 - -> DoOrListComp - -> (TcType s -> TcType s) -- Relationship type of pat and rhs in pat <- rhs - -> (TcStmt s -> Maybe (TcType s) -> thing -> thing) - -> RenamedStmt - -> TcM s (thing, LIE s) - -> TcM s (thing, LIE s) - -tcStmt tc_expr do_or_lc m combine stmt@(ReturnStmt exp) do_next - = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True } ) - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) -> - returnTc (ReturnStmt exp', exp_lie, m exp_ty) - ) `thenTc` \ (stmt', stmt_lie, stmt_ty) -> - do_next `thenTc` \ (thing', thing_lie) -> - returnTc (combine stmt' (Just stmt_ty) thing', - stmt_lie `plusLIE` thing_lie) - -tcStmt tc_expr do_or_lc m combine stmt@(GuardStmt exp src_loc) do_next - = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True } ) - tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) -> - unifyTauTy boolTy exp_ty `thenTc_` - returnTc (GuardStmt exp' src_loc, exp_lie) - )) `thenTc` \ (stmt', stmt_lie) -> - do_next `thenTc` \ (thing', thing_lie) -> - returnTc (combine stmt' Nothing thing', - stmt_lie `plusLIE` thing_lie) - -tcStmt tc_expr do_or_lc m combine stmt@(ExprStmt exp src_loc) do_next - = ASSERT( case do_or_lc of { DoStmt -> True; ListComp -> False } ) - tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) -> - -- Check that exp has type (m tau) for some tau (doesn't matter what) - newTyVarTy mkTypeKind `thenNF_Tc` \ tau -> - unifyTauTy (m tau) exp_ty `thenTc_` - returnTc (ExprStmt exp' src_loc, exp_lie, exp_ty) - )) `thenTc` \ (stmt', stmt_lie, stmt_ty) -> - do_next `thenTc` \ (thing', thing_lie) -> - returnTc (combine stmt' (Just stmt_ty) thing', - stmt_lie `plusLIE` thing_lie) - -tcStmt tc_expr do_or_lc m combine stmt@(BindStmt pat exp src_loc) do_next - = newMonoIds (collectPatBinders pat) mkBoxedTypeKind $ \ _ -> - tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - tcPat pat `thenTc` \ (pat', pat_lie, pat_ty) -> - tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) -> - unifyTauTy (m pat_ty) exp_ty `thenTc_` - - -- NB: the environment has been extended with the new binders - -- which the rhs can't "see", but the renamer should have made - -- sure that everything is distinct by now, so there's no problem. - -- Putting the tcExpr before the newMonoIds messes up the nesting - -- of error contexts, so I didn't bother - - returnTc (BindStmt pat' exp' src_loc, pat_lie `plusLIE` exp_lie) - )) `thenTc` \ (stmt', stmt_lie) -> - do_next `thenTc` \ (thing', thing_lie) -> - returnTc (combine stmt' Nothing thing', - stmt_lie `plusLIE` thing_lie) - -tcStmt tc_expr do_or_lc m combine (LetStmt binds) do_next - = tcBindsAndThen -- No error context, but a binding group is - combine' -- rather a large thing for an error context anyway - binds - do_next - where - combine' is_rec binds' thing' = combine (LetStmt (MonoBind binds' [] is_rec)) Nothing thing' +#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} %************************************************************************ @@ -896,160 +847,212 @@ tcStmt tc_expr do_or_lc m combine (LetStmt binds) do_next Game plan for record bindings ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -For each binding - field = value -1. look up "field", to find its selector Id, which must have type - forall a1..an. T a1 .. an -> tau - where tau is the type of the field. +1. Find the TyCon for the bindings, from the first field label. + +2. Instantiate its tyvars and unify (T a1 .. an) with expected_ty. -2. Instantiate this type +For each binding field = value -3. Unify the (T a1 .. an) part with the "expected result type", which - is passed in. This checks that all the field labels come from the - same type. +3. Instantiate the field type (from the field label) using the type + envt from step 2. -4. Type check the value using tcArg, passing tau as the expected - argument type. +4 Type check the value using tcArg, passing the field type as + the expected argument type. This extends OK when the field types are universally quantified. -Actually, to save excessive creation of fresh type variables, -we \begin{code} tcRecordBinds - :: TcType s -- Expected type of whole record - -> RenamedRecordBinds - -> TcM s (TcRecordBinds s, LIE s) + :: TyCon -- Type constructor for the record + -> [TcType] -- Args of this type constructor + -> HsRecordBinds Name + -> TcM (HsRecordBinds TcId) -tcRecordBinds expected_record_ty rbinds - = mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) -> - returnTc (rbinds', plusLIEs lies) +tcRecordBinds tycon ty_args rbinds + = mappM do_bind rbinds where - do_bind (field_label, rhs, pun_flag) - = tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id -> + tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args + + 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) + in ASSERT( isRecordSelector sel_id ) -- 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 - tcInstId sel_id `thenNF_Tc` \ (_, _, tau) -> + tcCheckSigma rhs field_ty `thenM` \ rhs' -> - -- Record selectors all have type - -- forall a1..an. T a1 .. an -> tau - ASSERT( maybeToBool (getFunTy_maybe tau) ) - let - -- Selector must have type RecordType -> FieldType - Just (record_ty, field_ty) = getFunTy_maybe tau - in - unifyTauTy expected_record_ty record_ty `thenTc_` - tcArg field_ty rhs `thenTc` \ (rhs', lie) -> - returnTc ((RealId 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) + +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_s_fields + = [ fl | (fl, str) <- field_info, + isMarkedStrict str, + not (fieldLabelName fl `elem` field_names_used) + ] + missing_ns_fields + = [ fl | (fl, str) <- field_info, + not (isMarkedStrict str), + not (fieldLabelName 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{@tcExprs@ typechecks a {\em list} of expressions} +\subsection{@tcCheckRhos@ typechecks a {\em list} of expressions} %* * %************************************************************************ \begin{code} -tcExprs :: [RenamedHsExpr] -> TcM s ([TcExpr s], LIE s, [TcType s]) +tcCheckRhos :: [LHsExpr Name] -> [TcType] -> TcM [LHsExpr TcId] -tcExprs [] = returnTc ([], emptyLIE, []) -tcExprs (expr:exprs) - = tcExpr expr `thenTc` \ (expr', lie1, ty) -> - tcExprs exprs `thenTc` \ (exprs', lie2, tys) -> - returnTc (expr':exprs', lie1 `plusLIE` lie2, ty:tys) +tcCheckRhos [] [] = returnM [] +tcCheckRhos (expr:exprs) (ty:tys) + = tcCheckRho expr ty `thenM` \ expr' -> + tcCheckRhos exprs tys `thenM` \ exprs' -> + returnM (expr':exprs') \end{code} -% ================================================= +%************************************************************************ +%* * +\subsection{Literals} +%* * +%************************************************************************ -Errors and contexts -~~~~~~~~~~~~~~~~~~~ +Overloaded literals. -Mini-utils: \begin{code} -pp_nest_hang :: String -> Doc -> Doc -pp_nest_hang label stuff = nest 2 (hang (text label) 4 stuff) +tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId) +tcLit lit res_ty + = zapExpectedTo res_ty (hsLitType lit) `thenM_` + returnM (HsLit lit) \end{code} -Boring and alphabetical: -\begin{code} -arithSeqCtxt expr sty - = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr sty expr) -branchCtxt b1 b2 sty - = sep [ptext SLIT("In the branches of a conditional:"), - pp_nest_hang "`then' branch:" (ppr sty b1), - pp_nest_hang "`else' branch:" (ppr sty b2)] +%************************************************************************ +%* * +\subsection{Errors and contexts} +%* * +%************************************************************************ -caseCtxt expr sty - = hang (ptext SLIT("In the case expression")) 4 (ppr sty expr) +Boring and alphabetical: +\begin{code} +arithSeqCtxt expr + = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr) -exprSigCtxt expr sty - = hang (ptext SLIT("In an expression with a type signature:")) - 4 (ppr sty expr) +parrSeqCtxt expr + = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr) -listCtxt expr sty - = hang (ptext SLIT("In the list element")) 4 (ppr sty expr) +caseCtxt expr + = hang (ptext SLIT("In the case expression:")) 4 (ppr expr) -predCtxt expr sty - = hang (ptext SLIT("In the predicate expression")) 4 (ppr sty expr) +caseScrutCtxt expr + = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr) -sectionRAppCtxt expr sty - = hang (ptext SLIT("In the right section")) 4 (ppr sty expr) +exprCtxt expr + = hang (ptext SLIT("In the expression:")) 4 (ppr expr) -sectionLAppCtxt expr sty - = hang (ptext SLIT("In the left section")) 4 (ppr sty expr) +fieldCtxt field_name + = ptext SLIT("In the") <+> quotes (ppr field_name) <+> ptext SLIT("field of a record") -funAppCtxt fun arg_no arg sty +funAppCtxt fun arg arg_no = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"), - ppr sty fun <> text ", namely"]) - 4 (ppr sty arg) - -stmtCtxt ListComp stmt sty - = hang (ptext SLIT("In a list-comprehension qualifer:")) - 4 (ppr sty stmt) + quotes (ppr fun) <> text ", namely"]) + 4 (quotes (ppr arg)) -stmtCtxt DoStmt stmt sty - = hang (ptext SLIT("In a do statement:")) - 4 (ppr sty stmt) +listCtxt expr + = hang (ptext SLIT("In the list element:")) 4 (ppr expr) -tooManyArgsCtxt f sty - = hang (ptext SLIT("Too many arguments in an application of the function")) - 4 (ppr sty f) +parrCtxt expr + = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr) -lurkingRank2Err fun fun_ty sty - = hang (hsep [ptext SLIT("Illegal use of"), ppr sty fun]) - 4 (vcat [text "It is applied to too few arguments,", - ptext SLIT("so that the result type has for-alls in it")]) +predCtxt expr + = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr) -rank2ArgCtxt arg expected_arg_ty sty - = hang (ptext SLIT("In a polymorphic function argument:")) - 4 (sep [(<>) (ppr sty arg) (ptext SLIT(" ::")), - ppr sty expected_arg_ty]) +appCtxt fun args + = ptext SLIT("In the application") <+> quotes (ppr the_app) + where + the_app = foldl mkHsApp fun args -- Used in error messages -badFieldsUpd rbinds sty +badFieldsUpd rbinds = hang (ptext SLIT("No constructor has all these fields:")) - 4 (interpp'SP sty 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 -recordUpdCtxt sty = ptext SLIT("In a record update construct") +notSelector field + = hsep [quotes (ppr field), ptext SLIT("is not a record selector")] -badFieldsCon con fields sty - = hsep [ptext SLIT("Constructor"), ppr sty con, - ptext SLIT("does not have field(s)"), interpp'SP sty fields] +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 -notSelector field sty - = hsep [ppr sty field, ptext SLIT("is not a record selector")] +#ifdef GHCI +polySpliceErr :: Id -> SDoc +polySpliceErr id + = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id) +#endif \end{code}