X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=84fc1d92c9946d55a85b8665a154299c1a8887d0;hb=fe548aebdad3520e51d92fcda6bec9d26d69aa4a;hp=65738ee6f9b0b12aeb9f55c7a966b2323802cc93;hpb=8de16184643ea3c2f9f30b5eaed18db6ef247760;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 65738ee..db7638a 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -1,168 +1,173 @@ % -% (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, tcId ) where +module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where -IMP_Ubiq() +#include "HsVersions.h" -import HsSyn ( HsExpr(..), Qualifier(..), Stmt(..), - HsBinds(..), Bind(..), MonoBinds(..), - ArithSeqInfo(..), HsLit(..), Sig, GRHSsAndBinds, - Match, Fake, InPat, OutPat, HsType, Fixity, - pprParendExpr, failureFreePat, collectPatBinders ) -import RnHsSyn ( SYN_IE(RenamedHsExpr), SYN_IE(RenamedQual), - SYN_IE(RenamedStmt), SYN_IE(RenamedRecordBinds) +#ifdef GHCI /* Only if bootstrapped */ +import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket ) +import HsSyn ( HsReify(..), ReifyFlavour(..) ) +import TcType ( isTauTy ) +import TcEnv ( bracketOK, tcMetaTy, checkWellStaged, metaLevel ) +import Name ( isExternalName ) +import qualified DsMeta +#endif + +import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), recBindFields ) +import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds ) +import TcHsSyn ( TcExpr, TcRecordBinds, hsLitType, mkHsDictApp, mkHsTyApp, mkHsLet, (<$>) ) +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 TcHsSyn ( SYN_IE(TcExpr), SYN_IE(TcQual), SYN_IE(TcStmt), - TcIdOcc(..), SYN_IE(TcRecordBinds), - mkHsTyApp - ) - -import TcMonad -import Inst ( Inst, InstOrigin(..), OverloadedLit(..), - SYN_IE(LIE), emptyLIE, plusLIE, plusLIEs, newOverloadedLit, - newMethod, newMethodWithGivenTy, newDicts ) import TcBinds ( tcBindsAndThen ) -import TcEnv ( tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey, - tcLookupGlobalValueByKey, newMonoIds, tcGetGlobalTyVars, - tcExtendGlobalTyVars - ) -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, - tcInstSigType, tcInstTcType, tcInstTheta, - newTyVarTy, zonkTcTyVars, zonkTcType ) -import TcKind ( TcKind ) - -import Class ( SYN_IE(Class), classSig ) -import FieldLabel ( fieldLabelName ) -import Id ( idType, dataConFieldLabels, dataConSig, SYN_IE(Id), GenId ) -import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind ) -import GenSpecEtc ( checkSigTyVars ) -import Name ( Name{-instance Eq-} ) -import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys, mkRhoTy, - getTyVar_maybe, getFunTy_maybe, instantiateTy, - splitForAllTy, splitRhoTy, splitSigmaTy, splitFunTy, - isTauTy, mkFunTys, tyVarsOfType, getForAllTy_maybe, - getAppDataTyCon, maybeAppDataTyCon +import TcEnv ( tcLookupClass, tcLookupGlobal_maybe, tcLookupIdLvl, + tcLookupTyCon, tcLookupDataCon, tcLookupId ) -import TyVar ( GenTyVar, SYN_IE(TyVarSet), unionTyVarSets, mkTyVarSet ) -import TysPrim ( intPrimTy, charPrimTy, doublePrimTy, - floatPrimTy, addrPrimTy, realWorldTy +import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig ) +import TcMonoType ( tcHsSigType, UserTypeCtxt(..) ) +import TcPat ( badFieldCon ) +import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, newTyVarTys, zonkTcType ) +import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv), + tcSplitFunTys, tcSplitTyConApp, mkTyVarTys, + isSigmaTy, mkFunTy, mkFunTys, + mkTyConApp, mkClassPred, + tyVarsOfTypes, isLinearPred, + liftedTypeKind, openTypeKind, + tcSplitSigmaTy, tidyOpenType ) -import TysWiredIn ( addrTy, - boolTy, charTy, stringTy, mkListTy, - mkTupleTy, mkPrimIoTy, stDataCon +import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon ) +import Id ( Id, idType, recordSelectorFieldLabel, isRecordSelector ) +import DataCon ( DataCon, dataConFieldLabels, dataConSig, dataConStrictMarks, dataConWrapId ) +import Name ( Name ) +import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons ) +import Subst ( mkTopTyVarSubst, substTheta, substTy ) +import VarSet ( emptyVarSet, elemVarSet ) +import TysWiredIn ( boolTy ) +import PrelNames ( cCallableClassName, cReturnableClassName, + enumFromName, enumFromThenName, + enumFromToName, enumFromThenToName, + enumFromToPName, enumFromThenToPName, + ioTyConName ) -import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy ) -import Unique ( Unique, cCallableClassKey, cReturnableClassKey, - enumFromClassOpKey, enumFromThenClassOpKey, - enumFromToClassOpKey, enumFromThenToClassOpKey, - thenMClassOpKey, zeroClassOpKey - ) -import Outputable ( interpp'SP ) -import PprType ( GenType, GenTyVar ) -- Instances -import Maybes ( maybeToBool ) -import Pretty -import Util -\end{code} +import ListSetOps ( minusList ) +import CmdLineOpts +import HscTypes ( TyThing(..) ) -\begin{code} -tcExpr :: RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s) +import Util +import Outputable +import FastString \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 :: RenamedHsExpr -- Expession to type check + -> TcSigmaType -- Expected type (could be a polytpye) + -> TcM TcExpr -- 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 (gen_fn <$> 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 :: RenamedHsExpr -> TcRhoType -> TcM TcExpr +tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty) + +tcInferRho :: RenamedHsExpr -> TcM (TcExpr, TcRhoType) +tcInferRho (HsVar name) = tcId name +tcInferRho expr = newHole `thenM` \ hole -> + tcMonoExpr expr (Infer hole) `thenM` \ expr' -> + readMutVar hole `thenM` \ rho_ty -> + returnM (expr', rho_ty) \end{code} + + %************************************************************************ %* * -\subsection{Literals} +\subsection{The TAUT rules for variables} %* * %************************************************************************ -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 :: RenamedHsExpr -- 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 + +tcMonoExpr (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 + = -- 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 `thenM` \ ip_ty -> + newIPDict (IPOcc 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) +tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty + = addErrCtxt (exprSigCtxt in_expr) $ + tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty -> + tcThingWithSig sig_tc_ty (tcCheckRho expr) res_ty `thenM` \ (co_fn, expr') -> + returnM (co_fn <$> expr') + +tcMonoExpr (HsType ty) res_ty + = failWithTc (text "Can't handle type argument:" <+> ppr ty) + -- 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} @@ -170,26 +175,26 @@ 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) +tcMonoExpr (HsLit lit) res_ty = tcLit lit res_ty +tcMonoExpr (HsOverLit lit) res_ty = zapExpectedType res_ty `thenM` \ res_ty' -> + newOverloadedLit (LiteralOrigin lit) lit res_ty' +tcMonoExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> + returnM (HsPar expr') +tcMonoExpr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> + returnM (HsSCC lbl expr') + +tcMonoExpr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation + returnM (HsCoreAnn lbl expr') +tcMonoExpr (NegApp expr neg_name) res_ty + = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty + -- ToDo: use tcSyntaxName + +tcMonoExpr (HsLam match) res_ty + = tcMatchLambda match res_ty `thenM` \ match' -> + returnM (HsLam match') + +tcMonoExpr (HsApp e1 e2) res_ty + = tcApp e1 [e2] res_ty \end{code} Note that the operators in sections are expected to be binary, and @@ -203,37 +208,113 @@ 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) +tcMonoExpr 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) -> +tcMonoExpr 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: - newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 -> - newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 -> - tcAddErrCtxt (sectionRAppCtxt in_expr) $ - unifyTauTy (mkFunTys [ty1, expr_ty] ty2) op_ty `thenTc_` +tcMonoExpr 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} - returnTc (SectionR op' expr', lie1 `plusLIE` lie2, mkFunTy ty1 ty2) +\begin{code} +tcMonoExpr (HsLet binds expr) res_ty + = tcBindsAndThen + HsLet + binds -- Bindings to check + (tcMonoExpr expr res_ty) + +tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty + = addSrcLoc src_loc $ + addErrCtxt (caseCtxt in_expr) $ + + -- 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 + + tcMatchesCase matches res_ty `thenM` \ (scrut_ty, matches') -> + + addErrCtxt (caseScrutCtxt scrut) ( + tcCheckRho scrut scrut_ty + ) `thenM` \ scrut' -> + + returnM (HsCase scrut' matches' src_loc) + +tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty + = addSrcLoc src_loc $ + addErrCtxt (predCtxt pred) ( + tcCheckRho pred boolTy ) `thenM` \ pred' -> + + zapExpectedType res_ty `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' src_loc) + +tcMonoExpr (HsDo do_or_lc stmts method_names _ src_loc) res_ty + = addSrcLoc src_loc $ + zapExpectedType res_ty `thenM` \ res_ty' -> + -- All comprehensions yield a monotype + tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (binds, stmts', methods') -> + returnM (mkHsLet binds (HsDo do_or_lc stmts' methods' res_ty' src_loc)) + +tcMonoExpr 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 + +tcMonoExpr 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 + +tcMonoExpr (ExplicitTuple exprs boxity) res_ty + = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys -> + tcCheckRhos exprs arg_tys `thenM` \ exprs' -> + returnM (ExplicitTuple exprs' boxity) \end{code} + +%************************************************************************ +%* * + Foreign calls +%* * +%************************************************************************ + The interesting thing about @ccall@ is that it is just a template which we instantiate by filling in details about the types of its argument and result (ie minimal typechecking is performed). So, the @@ -242,254 +323,330 @@ 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 -> +tcMonoExpr e0@(HsCCall lbl args may_gc is_casm ignored_fake_result_ty) res_ty + = getDOpts `thenM` \ dflags -> + + checkTc (not (is_casm && dopt_HscLang dflags /= HscC)) + (vcat [text "_casm_ is only supported when compiling via C (-fvia-C).", + text "Either compile with -fvia-C, or, better, rewrite your code", + text "to use the foreign function interface. _casm_s are deprecated", + text "and support for them may one day disappear."]) + `thenM_` + + -- Get the callable and returnable classes. + tcLookupClass cCallableClassName `thenM` \ cCallableClass -> + tcLookupClass cReturnableClassName `thenM` \ cReturnableClass -> + tcLookupTyCon ioTyConName `thenM` \ ioTyCon -> let new_arg_dict (arg, arg_ty) - = newDicts (CCallOrigin (_UNPK_ lbl) (Just arg)) - [(cCallableClass, arg_ty)] `thenNF_Tc` \ (arg_dicts, _) -> - returnNF_Tc arg_dicts -- Actually a singleton bag + = newDicts (CCallOrigin (unpackFS lbl) (Just arg)) + [mkClassPred cCallableClass [arg_ty]] `thenM` \ arg_dicts -> + returnM arg_dicts -- Actually a singleton bag - result_origin = CCallOrigin (_UNPK_ lbl) Nothing {- Not an arg -} + result_origin = CCallOrigin (unpackFS lbl) Nothing {- Not an arg -} in -- Arguments - tcExprs args `thenTc` \ (args', args_lie, arg_tys) -> + let tv_idxs | null args = [] + | otherwise = [1..length args] + in + newTyVarTys (length tv_idxs) openTypeKind `thenM` \ arg_tys -> + tcCheckRhos args arg_tys `thenM` \ args' -> - -- The argument types can be unboxed or boxed; the result - -- type must, however, be boxed since it's an argument to the PrimIO + -- 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 mkBoxedTypeKind `thenNF_Tc` \ result_ty -> + newTyVarTy liftedTypeKind `thenM` \ result_ty -> + let + io_result_ty = mkTyConApp ioTyCon [result_ty] + in + zapExpectedTo res_ty io_result_ty `thenM_` -- 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, _) -> - - 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) + mappM new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenM` \ ccarg_dicts_s -> + newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenM` \ ccres_dict -> + extendLIEs (ccres_dict ++ concat ccarg_dicts_s) `thenM_` + returnM (HsCCall lbl args' may_gc is_casm io_result_ty) \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) - = tcBindsAndThen - HsLet -- The combiner - binds -- Bindings to check - (tcExpr expr) -- Typechecker for the expression -tcExpr in_expr@(HsCase expr matches src_loc) - = tcAddSrcLoc src_loc $ - tcExpr expr `thenTc` \ (expr',lie1,expr_ty) -> - newTyVarTy mkTypeKind `thenNF_Tc` \ result_ty -> - - tcAddErrCtxt (caseCtxt in_expr) $ - tcMatchesCase (mkFunTy expr_ty result_ty) matches - `thenTc` \ (matches',lie2) -> - - returnTc (HsCase expr' matches' src_loc, plusLIE lie1 lie2, result_ty) - -tcExpr (HsIf pred b1 b2 src_loc) - = tcAddSrcLoc src_loc $ - tcExpr pred `thenTc` \ (pred',lie1,predTy) -> +%************************************************************************ +%* * + Record construction and update +%* * +%************************************************************************ - tcAddErrCtxt (predCtxt pred) ( - unifyTauTy boolTy predTy - ) `thenTc_` +\begin{code} +tcMonoExpr expr@(RecordCon con_name rbinds) res_ty + = addErrCtxt (recordConCtxt expr) $ + tcId con_name `thenM` \ (con_expr, con_tau) -> + let + (_, record_ty) = tcSplitFunTys con_tau + (tycon, ty_args) = tcSplitTyConApp record_ty + in + ASSERT( isAlgTyCon tycon ) + zapExpectedTo res_ty record_ty `thenM_` - tcExpr b1 `thenTc` \ (b1',lie2,result_ty) -> - tcExpr b2 `thenTc` \ (b2',lie3,b2Ty) -> + -- Check that the record bindings match the constructor + -- con_name is syntactically constrained to be a data constructor + tcLookupDataCon con_name `thenM` \ data_con -> + let + bad_fields = badFields rbinds data_con + in + 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 - tcAddErrCtxt (branchCtxt b1 b2) $ - unifyTauTy result_ty b2Ty `thenTc_` + -- Typecheck the record bindings + tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' -> + + -- Check for missing fields + checkMissingFields data_con rbinds `thenM_` - returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3), result_ty) + returnM (RecordConOut data_con con_expr rbinds') -tcExpr (ListComp expr quals) - = tcListComp expr quals `thenTc` \ ((expr',quals'), lie, ty) -> - returnTc (ListComp expr' quals', lie, ty) -\end{code} +-- The main complication with RecordUpd is that we need to explicitly +-- handle the *non-updated* fields. Consider: +-- +-- data T a b = MkT1 { fa :: a, fb :: b } +-- | MkT2 { fa :: a, fc :: Int -> Int } +-- | MkT3 { fd :: a } +-- +-- upd :: T a b -> c -> T a c +-- upd t x = t { fb = x} +-- +-- The type signature on upd is correct (i.e. the result should not be (T a b)) +-- because upd should be equivalent to: +-- +-- upd t x = case t of +-- MkT1 p q -> MkT1 p x +-- MkT2 a b -> MkT2 p b +-- MkT3 d -> error ... +-- +-- So we need to give a completely fresh type to the result record, +-- and then constrain it by the fields that are *not* updated ("p" above). +-- +-- Note that because MkT3 doesn't contain all the fields being updated, +-- its RHS is simply an error, so it doesn't impose any type constraints +-- +-- All this is done in STEP 4 below. -\begin{code} -tcExpr expr@(HsDo stmts src_loc) - = tcDoStmts stmts src_loc -\end{code} +tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty + = addErrCtxt (recordUpdCtxt expr) $ -\begin{code} -tcExpr (ExplicitList []) - = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty -> - returnTc (ExplicitListOut tyvar_ty [], emptyLIE, mkListTy tyvar_ty) + -- STEP 0 + -- Check that the field names are really field names + ASSERT( notNull rbinds ) + let + field_names = recBindFields rbinds + in + mappM tcLookupGlobal_maybe field_names `thenM` \ maybe_sel_ids -> + let + bad_guys = [ addErrTc (notSelector field_name) + | (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids, + not (is_selector maybe_sel_id) + ] + is_selector (Just (AnId sel_id)) = isRecordSelector sel_id -- Excludes class ops + is_selector other = False + in + checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_` + + -- 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 + 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 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) `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 = mkTyConApp tycon result_inst_tys + in + 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 + -- which type arguments must be the same in updatee and result. + -- + -- WARNING: this code assumes that all data_cons in a common tycon + -- have FieldLabels abstracted over the same tyvars. + let + upd_field_lbls = map recordSelectorFieldLabel (recBindFields rbinds') + con_field_lbls_s = map dataConFieldLabels data_cons + -- A constructor is only relevant to this process if + -- it contains all the fields that are being updated + relevant_field_lbls_s = filter is_relevant con_field_lbls_s + is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls -tcExpr in_expr@(ExplicitList exprs) -- Non-empty list - = tcExprs exprs `thenTc` \ (exprs', lie, tys@(elt_ty:_)) -> - tcAddErrCtxt (listCtxt in_expr) $ - unifyTauTyList tys `thenTc_` - returnTc (ExplicitListOut elt_ty exprs', lie, mkListTy elt_ty) + non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls + common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls) -tcExpr (ExplicitTuple exprs) - = tcExprs exprs `thenTc` \ (exprs', lie, tys) -> - returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys) + mk_inst_ty (tyvar, result_inst_ty) + | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type + | otherwise = newTyVarTy liftedTypeKind -- Fresh type + in + mappM mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenM` \ inst_tys -> -tcExpr (RecordCon (HsVar con) rbinds) - = tcId con `thenNF_Tc` \ (con_expr, con_lie, con_tau) -> + -- STEP 5 + -- Typecheck the expression to be updated let - (_, record_ty) = splitFunTy con_tau + record_ty = mkTyConApp tycon inst_tys in - -- Con is syntactically constrained to be a data constructor - ASSERT( maybeToBool (maybeAppDataTyCon record_ty ) ) + 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 pattern matching over the data cons. + -- + -- What dictionaries do we need? + -- We just take the context of the type constructor + let + theta' = substTheta inst_env (tyConTheta tycon) + in + newDicts RecordUpdOrigin theta' `thenM` \ dicts -> + extendLIEs dicts `thenM_` - tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) -> + -- Phew! + returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds') +\end{code} - -- Check that the record bindings match the constructor - tcLookupGlobalValue con `thenNF_Tc` \ con_id -> - checkTc (checkRecordFields rbinds con_id) - (badFieldsCon con rbinds) `thenTc_` - returnTc (RecordCon con_expr rbinds', con_lie `plusLIE` rbinds_lie, record_ty) +%************************************************************************ +%* * + Arithmetic sequences e.g. [a,b..] + and their parallel-array counterparts e.g. [: a,b.. :] + +%* * +%************************************************************************ --- One small complication in RecordUpd is that we have to generate some --- dictionaries for the data type context, since we are going to --- do some construction. --- --- 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. +\begin{code} +tcMonoExpr (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 (HsVar enum_from) (From expr')) + +tcMonoExpr 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 (HsVar enum_from_then) (FromThen expr1' expr2')) + + +tcMonoExpr 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 (HsVar enum_from_to) (FromTo expr1' expr2')) + +tcMonoExpr 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 (HsVar eft) (FromThenTo expr1' expr2' expr3')) + +tcMonoExpr 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 (HsVar enum_from_to) (FromTo expr1' expr2')) + +tcMonoExpr 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 (HsVar eft) (FromThenTo expr1' expr2' expr3')) + +tcMonoExpr (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} -tcExpr (RecordUpd record_expr rbinds) - = ASSERT( not (null rbinds) ) - tcAddErrCtxt recordUpdCtxt $ - tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) -> - tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) -> +%************************************************************************ +%* * + Template Haskell +%* * +%************************************************************************ - -- Check that the field names are plausible - zonkTcType record_ty `thenNF_Tc` \ record_ty' -> - let - (tycon, inst_tys, data_cons) = --trace "TcExpr.getAppDataTyCon" $ - getAppDataTyCon record_ty' - -- The record binds are non-empty (syntax); so at least one field - -- label will have been unified with record_ty by tcRecordBinds; - -- field labels must be of data type; hencd the getAppDataTyCon must succeed. - (tyvars, theta, _, _) = dataConSig (head data_cons) - in - tcInstTheta (zipEqual "tcExpr:RecordUpd" tyvars inst_tys) theta `thenNF_Tc` \ theta' -> - newDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) -> - checkTc (any (checkRecordFields rbinds) data_cons) - (badFieldsUpd rbinds) `thenTc_` - - returnTc (RecordUpdOut record_expr' dicts rbinds', - con_lie `plusLIE` record_lie `plusLIE` rbinds_lie, - 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_` - - 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) - -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) -> - - 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) -> - - 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 + +tcMonoExpr (HsSplice n expr loc) res_ty = addSrcLoc loc (tcSpliceExpr n expr res_ty) +tcMonoExpr (HsBracket brack loc) res_ty = addSrcLoc loc (tcBracket brack res_ty) + +tcMonoExpr (HsReify (Reify flavour name)) res_ty + = addErrCtxt (ptext SLIT("At the reification of") <+> ppr name) $ + tcMetaTy tycon_name `thenM` \ reify_ty -> + zapExpectedTo res_ty reify_ty `thenM_` + returnM (HsReify (ReifyOut flavour name)) + where + tycon_name = case flavour of + ReifyDecl -> DsMeta.declTyConName + ReifyType -> DsMeta.typeTyConName + ReifyFixity -> pprPanic "tcMonoExpr: cant do reifyFixity yet" (ppr name) +#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) +tcMonoExpr other _ = pprPanic "tcMonoExpr" (ppr other) \end{code} + %************************************************************************ %* * \subsection{@tcApp@ typchecks an application} @@ -497,474 +654,471 @@ 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 - = -- 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) -> - - tcApp_help fun 1 fun_ty args `thenTc` \ (args', lie_args, res_ty) -> - -- 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_` +tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args + -> Expected TcRhoType -- Expected result type of application + -> TcM TcExpr -- Translated fun and args - returnTc (fun', args', lie_fun `plusLIE` lie_args, res_ty) +tcApp (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 + 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.] + + 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 <$> foldl HsApp fun' args') + + +-- If an error happens we try to figure out whether the +-- function has been given too many or too few arguments, +-- and say so. +-- 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 :: 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 - -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 +tcArg :: RenamedHsExpr -- The function (for error messages) + -> (RenamedHsExpr, TcSigmaType, Int) -- Actual argument and expected arg type + -> TcM TcExpr -- Resulting argument and LIE - mk_binds [] = EmptyBinds - mk_binds ((inst,rhs):inst_binds) - = (SingleBind (NonRecBind (VarMonoBind inst rhs))) `ThenBinds` - mk_binds inst_binds +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 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 -tcId name - = -- Look up the Id and instantiate its type - tcLookupLocalValue name `thenNF_Tc` \ maybe_local -> +\begin{code} +tcId :: Name -> TcM (TcExpr, TcRhoType) +tcId name -- Look up the Id and instantiate its type + = -- First check whether it's a DataCon + -- Reason: we must not forget to chuck in the + -- constraints from their "silly context" + tcLookupGlobal_maybe name `thenM` \ maybe_thing -> + case maybe_thing of { + Just (ADataCon data_con) -> inst_data_con data_con ; + other -> + + -- OK, so now look for ordinary Ids + tcLookupIdLvl name `thenM` \ (id, bind_lvl) -> + +#ifndef GHCI + loop (HsVar id) (idType id) -- Non-TH case + +#else /* GHCI is on */ + -- Check for cross-stage lifting + getStage `thenM` \ use_stage -> + case use_stage of + Brack use_lvl ps_var lie_var + | use_lvl > bind_lvl && not (isExternalName name) + -> -- E.g. \x -> [| h x |] + -- We must behave as if the reference to x was + -- h $(lift x) + -- We use 'x' itself as the splice proxy, used by + -- the desugarer to stitch it all back together. + -- If 'x' occurs many times we may get many identical + -- bindings of the same splice proxy, but that doesn't + -- matter, although it's a mite untidy. + -- + -- NB: During type-checking, isExernalName is true of + -- top level things, and false of nested bindings + -- Top-level things don't need lifting. + + let + id_ty = idType id + in + checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_` + -- 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, HsApp (HsVar lift) (HsVar id)) : ps) `thenM_` - case maybe_local of - Just tc_id -> instantiate_it (TcId tc_id) (idType tc_id) + returnM (HsVar id, id_ty)) - 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 + other -> + checkWellStaged (quotes (ppr id)) bind_lvl use_stage `thenM_` + loop (HsVar id) (idType id) +#endif + } 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 - | null theta -- Is it overloaded? - = returnNF_Tc (mkHsTyApp (HsVar tc_id_occ) arg_tys, emptyLIE, tau) - - | otherwise -- 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 - (theta, tau) = splitRhoTy rho - arg_tys = mkTyVarTys tyvars + orig = OccurrenceOf name + + 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_` + returnM (mkHsDictApp (mkHsTyApp (HsVar (dataConWrapId data_con)) ty_args) + (map instToId ex_dicts), + mkFunTys arg_tys result_ty) \end{code} %************************************************************************ %* * -\subsection{@tcQuals@ typechecks list-comprehension qualifiers} +\subsection{Record bindings} %* * %************************************************************************ -\begin{code} -tcListComp expr [] - = tcExpr expr `thenTc` \ (expr', lie, ty) -> - returnTc ((expr',[]), lie, mkListTy ty) - -tcListComp expr (qual@(FilterQual filter) : quals) - = tcAddErrCtxt (qualCtxt qual) ( - tcExpr filter `thenTc` \ (filter', filter_lie, filter_ty) -> - unifyTauTy boolTy filter_ty `thenTc_` - returnTc (FilterQual filter', filter_lie) - ) `thenTc` \ (qual', qual_lie) -> - - tcListComp expr quals `thenTc` \ ((expr',quals'), rest_lie, res_ty) -> - - returnTc ((expr', qual' : quals'), - qual_lie `plusLIE` rest_lie, - res_ty) - -tcListComp expr (qual@(GeneratorQual pat rhs) : quals) - = newMonoIds binder_names mkBoxedTypeKind (\ ids -> - - tcAddErrCtxt (qualCtxt qual) ( - tcPat pat `thenTc` \ (pat', lie_pat, pat_ty) -> - tcExpr rhs `thenTc` \ (rhs', lie_rhs, rhs_ty) -> - -- 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 - - unifyTauTy (mkListTy pat_ty) rhs_ty `thenTc_` - returnTc (GeneratorQual pat' rhs', - lie_pat `plusLIE` lie_rhs) - ) `thenTc` \ (qual', lie_qual) -> - - tcListComp expr quals `thenTc` \ ((expr',quals'), lie_rest, res_ty) -> - - returnTc ((expr', qual' : quals'), - lie_qual `plusLIE` lie_rest, - res_ty) - ) - where - binder_names = collectPatBinders pat - -tcListComp expr (LetQual binds : quals) - = tcBindsAndThen -- No error context, but a binding group is - combine -- rather a large thing for an error context anyway - binds - (tcListComp expr quals) - where - combine binds' (expr',quals') = (expr', LetQual binds' : quals') -\end{code} - - -%************************************************************************ -%* * -\subsection{@tcDoStmts@ typechecks a {\em list} of do statements} -%* * -%************************************************************************ - -\begin{code} -tcDoStmts stmts src_loc - = -- get the Monad and MonadZero classes - -- create type consisting of a fresh monad tyvar - tcAddSrcLoc src_loc $ - newTyVarTy (mkArrowKind mkBoxedTypeKind mkBoxedTypeKind) `thenNF_Tc` \ m -> - - - -- Build the then and zero methods in case we need them - tcLookupGlobalValueByKey thenMClassOpKey `thenNF_Tc` \ then_sel_id -> - tcLookupGlobalValueByKey zeroClassOpKey `thenNF_Tc` \ zero_sel_id -> - newMethod DoOrigin - (RealId then_sel_id) [m] `thenNF_Tc` \ (m_lie, then_id) -> - newMethod DoOrigin - (RealId zero_sel_id) [m] `thenNF_Tc` \ (mz_lie, zero_id) -> - - let - get_m_arg ty - = newTyVarTy mkTypeKind `thenNF_Tc` \ arg_ty -> - unifyTauTy (mkAppTy m arg_ty) ty `thenTc_` - returnTc arg_ty - - go [stmt@(ExprStmt exp src_loc)] - = tcAddSrcLoc src_loc $ - tcSetErrCtxt (stmtCtxt stmt) $ - tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) -> - returnTc ([ExprStmt exp' src_loc], exp_lie, exp_ty) - - go (stmt@(ExprStmt exp src_loc) : stmts) - = tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt stmt) ( - tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) -> - get_m_arg exp_ty `thenTc` \ a -> - returnTc (a, exp', exp_lie) - )) `thenTc` \ (a, exp', exp_lie) -> - go stmts `thenTc` \ (stmts', stmts_lie, stmts_ty) -> - get_m_arg stmts_ty `thenTc` \ b -> - returnTc (ExprStmtOut exp' src_loc a b : stmts', - exp_lie `plusLIE` stmts_lie `plusLIE` m_lie, - stmts_ty) - - go (stmt@(BindStmt pat exp src_loc) : stmts) - = newMonoIds (collectPatBinders pat) mkBoxedTypeKind $ \ _ -> - tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt stmt) ( - tcPat pat `thenTc` \ (pat', pat_lie, pat_ty) -> - tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) -> - -- See comments with tcListComp on GeneratorQual - - get_m_arg exp_ty `thenTc` \ a -> - unifyTauTy pat_ty a `thenTc_` - returnTc (a, pat', exp', pat_lie `plusLIE` exp_lie) - )) `thenTc` \ (a, pat', exp', stmt_lie) -> - go stmts `thenTc` \ (stmts', stmts_lie, stmts_ty) -> - get_m_arg stmts_ty `thenTc` \ b -> - returnTc (BindStmtOut pat' exp' src_loc a b : stmts', - stmt_lie `plusLIE` stmts_lie `plusLIE` m_lie `plusLIE` - (if failureFreePat pat' then emptyLIE else mz_lie), - stmts_ty) - - go (LetStmt binds : stmts) - = tcBindsAndThen -- No error context, but a binding group is - combine -- rather a large thing for an error context anyway - binds - (go stmts) - where - combine binds' stmts' = LetStmt binds' : stmts' - in - - go stmts `thenTc` \ (stmts', final_lie, final_ty) -> - returnTc (HsDoOut stmts' then_id zero_id src_loc, - final_lie, - final_ty) -\end{code} - 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 + :: TyCon -- Type constructor for the record + -> [TcType] -- Args of this type constructor -> RenamedRecordBinds - -> TcM s (TcRecordBinds s, LIE s) + -> TcM TcRecordBinds -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 -> - tcInstId sel_id `thenNF_Tc` \ (_, _, tau) -> + tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args - -- Record selectors all have type - -- forall a1..an. T a1 .. an -> tau - ASSERT( maybeToBool (getFunTy_maybe tau) ) + do_bind (field_lbl_name, rhs) + = addErrCtxt (fieldCtxt field_lbl_name) $ + tcLookupId field_lbl_name `thenM` \ sel_id -> let - -- Selector must have type RecordType -> FieldType - Just (record_ty, field_ty) = getFunTy_maybe tau + field_lbl = recordSelectorFieldLabel sel_id + field_ty = substTy tenv (fieldLabelType field_lbl) in - unifyTauTy expected_record_ty record_ty `thenTc_` - tcArg field_ty rhs `thenTc` \ (rhs', lie) -> - returnTc ((RealId sel_id, rhs', pun_flag), lie) + 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 + + tcCheckSigma rhs field_ty `thenM` \ rhs' -> -checkRecordFields :: RenamedRecordBinds -> Id -> Bool -- True iff all the fields in - -- RecordBinds are field of the - -- specified constructor -checkRecordFields rbinds data_con - = all ok rbinds - where - data_con_fields = dataConFieldLabels data_con + returnM (sel_id, rhs') - ok (field_name, _, _) = any (match (getName field_name)) data_con_fields +badFields rbinds data_con + = filter (not . (`elem` field_names)) (recBindFields rbinds) + where + field_names = map fieldLabelName (dataConFieldLabels data_con) + +checkMissingFields :: DataCon -> RenamedRecordBinds -> 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)) - match field_name field_label = field_name == fieldLabelName field_label + 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 = dropList ex_theta (dataConStrictMarks data_con) + -- The 'drop' is because dataConStrictMarks + -- includes the existential dictionaries + (_, _, _, ex_theta, _, _) = dataConSig 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 :: [RenamedHsExpr] -> [TcType] -> TcM [TcExpr] -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 -> Pretty -> Pretty -pp_nest_hang label stuff = ppNest 2 (ppHang (ppStr label) 4 stuff) +tcLit :: HsLit -> Expected TcRhoType -> TcM TcExpr +tcLit (HsLitLit s _) res_ty + = zapExpectedType res_ty `thenM` \ res_ty' -> + tcLookupClass cCallableClassName `thenM` \ cCallableClass -> + newDicts (LitLitOrigin (unpackFS s)) + [mkClassPred cCallableClass [res_ty']] `thenM` \ dicts -> + extendLIEs dicts `thenM_` + returnM (HsLit (HsLitLit s res_ty')) + +tcLit lit res_ty + = zapExpectedTo res_ty (hsLitType lit) `thenM_` + returnM (HsLit lit) \end{code} + +%************************************************************************ +%* * +\subsection{Errors and contexts} +%* * +%************************************************************************ + Boring and alphabetical: \begin{code} -arithSeqCtxt expr sty - = ppHang (ppStr "In an arithmetic sequence:") 4 (ppr sty expr) +arithSeqCtxt expr + = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr) -branchCtxt b1 b2 sty - = ppSep [ppStr "In the branches of a conditional:", - pp_nest_hang "`then' branch:" (ppr sty b1), - pp_nest_hang "`else' branch:" (ppr sty b2)] +parrSeqCtxt expr + = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr) -caseCtxt expr sty - = ppHang (ppStr "In a case expression:") 4 (ppr sty expr) +caseCtxt expr + = hang (ptext SLIT("In the case expression:")) 4 (ppr expr) -exprSigCtxt expr sty - = ppHang (ppStr "In an expression with a type signature:") - 4 (ppr sty expr) +caseScrutCtxt expr + = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr) -listCtxt expr sty - = ppHang (ppStr "In a list expression:") 4 (ppr sty expr) +exprSigCtxt expr + = hang (ptext SLIT("When checking the type signature of the expression:")) + 4 (ppr expr) -predCtxt expr sty - = ppHang (ppStr "In a predicate expression:") 4 (ppr sty expr) +exprCtxt expr + = hang (ptext SLIT("In the expression:")) 4 (ppr expr) -sectionRAppCtxt expr sty - = ppHang (ppStr "In a right section:") 4 (ppr sty expr) +fieldCtxt field_name + = ptext SLIT("In the") <+> quotes (ppr field_name) <+> ptext SLIT("field of a record") -sectionLAppCtxt expr sty - = ppHang (ppStr "In a left section:") 4 (ppr sty expr) +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)) -funAppCtxt fun arg_no arg sty - = ppHang (ppCat [ ppStr "In the", speakNth arg_no, ppStr "argument of", - ppr sty fun `ppBeside` ppStr ", namely"]) - 4 (pprParendExpr sty arg) +listCtxt expr + = hang (ptext SLIT("In the list element:")) 4 (ppr expr) -qualCtxt qual sty - = ppHang (ppStr "In a list-comprehension qualifer:") - 4 (ppr sty qual) +parrCtxt expr + = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr) -stmtCtxt stmt sty - = ppHang (ppStr "In a do statement:") - 4 (ppr sty stmt) +predCtxt expr + = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr) -tooManyArgsCtxt f sty - = ppHang (ppStr "Too many arguments in an application of the function") - 4 (ppr sty f) +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 sty - = ppHang (ppCat [ppStr "Illegal use of", ppr sty fun]) - 4 (ppAboves [ppStr "It is applied to too few arguments,", - ppStr "so that the result type has for-alls in it"]) +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]) -rank2ArgCtxt arg expected_arg_ty sty - = ppHang (ppStr "In a polymorphic function argument:") - 4 (ppSep [ppBeside (ppr sty arg) (ppStr " ::"), - ppr sty expected_arg_ty]) +badFieldsUpd rbinds + = hang (ptext SLIT("No constructor has all these fields:")) + 4 (pprQuotedList (recBindFields rbinds)) -badFieldsUpd rbinds sty - = ppHang (ppStr "No constructor has all these fields:") - 4 (interpp'SP sty fields) - where - fields = [field | (field, _, _) <- rbinds] +recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr +recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr -recordUpdCtxt sty = ppStr "In a record update construct" +notSelector field + = hsep [quotes (ppr field), ptext SLIT("is not a record selector")] -badFieldsCon con rbinds sty - = ppHang (ppBesides [ppStr "Inconsistent constructor:", ppr sty con]) - 4 (ppBesides [ppStr "and fields:", 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 + +polySpliceErr :: Id -> SDoc +polySpliceErr id + = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id) + +wrongArgsCtxt too_many_or_few fun args + = hang (ptext SLIT("Probable cause:") <+> quotes (ppr fun) + <+> ptext SLIT("is applied to") <+> text too_many_or_few + <+> ptext SLIT("arguments in the call")) + 4 (parens (ppr the_app)) where - fields = [field | (field, _, _) <- rbinds] + the_app = foldl HsApp fun args -- Used in error messages \end{code}