X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=a1bac3021e4e91e24ecc5e100ce9771de2199358;hb=4e342297f796001e7107d8c348bb023168954bc7;hp=44964cffc80d925d3c346ab21a448c27ca5bdc24;hpb=c29022c49449b7d8862dcc2259e16cafe9461945;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 44964cf..a1bac30 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -1,174 +1,188 @@ % -% (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} -module TcExpr ( tcExpr, tcStmt, tcId ) where +module TcExpr ( tcApp, tcExpr, tcMonoExpr, tcPolyExpr, tcId ) where #include "HsVersions.h" import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), - HsBinds(..), Stmt(..), DoOrListComp(..), - failureFreePat, collectPatBinders - ) -import RnHsSyn ( RenamedHsExpr, - RenamedStmt, RenamedRecordBinds - ) -import TcHsSyn ( TcExpr, TcStmt, - TcRecordBinds, - mkHsTyApp + StmtCtxt(..), mkMonoBind ) +import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds ) +import TcHsSyn ( TcExpr, TcRecordBinds, mkHsLet ) import TcMonad import BasicTypes ( RecFlag(..) ) -import Inst ( Inst, InstOrigin(..), OverloadedLit(..), - LIE, emptyLIE, plusLIE, plusLIEs, newOverloadedLit, - newMethod, newMethodWithGivenTy, newDicts ) -import TcBinds ( tcBindsAndThen, checkSigTyVars, sigThetaCtxt ) -import TcEnv ( TcIdOcc(..), tcInstId, - tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey, - tcLookupGlobalValueByKey, newMonoIds, - tcExtendGlobalTyVars, tcLookupGlobalValueMaybe, - tcLookupTyCon +import Inst ( InstOrigin(..), + LIE, mkLIE, emptyLIE, unitLIE, plusLIE, plusLIEs, + newOverloadedLit, newMethod, newIPDict, + newDicts, newClassDicts, + instToId, tcInstId + ) +import TcBinds ( tcBindsAndThen ) +import TcEnv ( TcTyThing(..), + tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe, + tcLookupTyCon, tcLookupDataCon, tcLookup, + tcExtendGlobalTyVars ) -import TcMatches ( tcMatchesCase, tcMatchExpected ) -import TcMonoType ( tcHsType ) -import TcPat ( tcPat ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( TcType, TcMaybe(..), - tcInstType, tcInstSigTcType, tcInstTyVars, - tcInstSigType, tcInstTcType, tcInstTheta, tcSplitRhoTy, +import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts ) +import TcMonoType ( tcHsSigType, checkSigTyVars, sigCtxt ) +import TcPat ( badFieldCon, simpleHsLitTy ) +import TcSimplify ( tcSimplifyCheck, tcSimplifyIPs ) +import TcType ( TcType, TcTauType, + tcInstTyVars, tcInstType, newTyVarTy, newTyVarTys, zonkTcType ) -import TcKind ( TcKind ) -import Class ( Class ) -import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType ) -import Id ( idType, dataConFieldLabels, dataConSig, recordSelectorFieldLabel, - isRecordSelector, - Id, GenId +import FieldLabel ( fieldLabelName, fieldLabelType, fieldLabelTyCon ) +import Id ( idType, recordSelectorFieldLabel, isRecordSelector ) +import DataCon ( dataConFieldLabels, dataConSig, + dataConStrictMarks, StrictnessMark(..) ) -import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind ) -import Name ( Name{-instance Eq-} ) -import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys, +import Name ( Name ) +import Type ( mkFunTy, mkAppTy, mkTyConTy, splitFunTy_maybe, splitFunTys, - mkTyConApp, - splitForAllTys, splitRhoTy, splitSigmaTy, + mkTyConApp, splitSigmaTy, isTauTy, tyVarsOfType, tyVarsOfTypes, - splitForAllTy_maybe, splitAlgTyConApp, splitAlgTyConApp_maybe + isSigmaTy, splitAlgTyConApp, splitAlgTyConApp_maybe, + liftedTypeKind, openTypeKind, mkArrowKind, + tidyOpenType ) -import TyVar ( emptyTyVarEnv, zipTyVarEnv, - elementOfTyVarSet, mkTyVarSet, tyVarSetToList - ) -import TyCon ( tyConDataCons ) -import TysPrim ( intPrimTy, charPrimTy, doublePrimTy, - floatPrimTy, addrPrimTy - ) -import TysWiredIn ( boolTy, charTy, stringTy ) -import PrelInfo ( ioTyCon_NAME ) -import Unify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy ) -import Unique ( Unique, cCallableClassKey, cReturnableClassKey, - enumFromClassOpKey, enumFromThenClassOpKey, - enumFromToClassOpKey, enumFromThenToClassOpKey, - thenMClassOpKey, zeroClassOpKey, returnMClassOpKey +import TyCon ( TyCon, tyConTyVars ) +import Subst ( mkTopTyVarSubst, substClasses, substTy ) +import VarSet ( elemVarSet ) +import TysWiredIn ( boolTy, mkListTy, listTyCon ) +import TcUnify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy ) +import PrelNames ( cCallableClassName, + cReturnableClassName, + enumFromName, enumFromThenName, + enumFromToName, enumFromThenToName, + thenMName, failMName, returnMName, ioTyConName ) import Outputable -import PprType ( GenType, GenTyVar ) -- Instances -import Maybes ( maybeToBool ) +import Maybes ( maybeToBool, mapMaybe ) import ListSetOps ( minusList ) import Util -\end{code} +import CmdLineOpts +import HscTypes ( TyThing(..) ) -\begin{code} -tcExpr :: RenamedHsExpr -- Expession to type check - -> TcType s -- Expected type (could be a type variable) - -> TcM s (TcExpr s, LIE s) \end{code} %************************************************************************ %* * -\subsection{The TAUT rules for variables} +\subsection{Main wrappers} %* * %************************************************************************ \begin{code} -tcExpr (HsVar name) res_ty - = tcId name `thenNF_Tc` \ (expr', lie, id_ty) -> - unifyTauTy res_ty id_ty `thenTc_` +tcExpr :: RenamedHsExpr -- Expession to type check + -> TcType -- Expected type (could be a polytpye) + -> TcM (TcExpr, LIE) - -- Check that the result type doesn't have any nested for-alls. - -- For example, a "build" on its own is no good; it must be - -- applied to something. - checkTc (isTauTy id_ty) - (lurkingRank2Err name id_ty) `thenTc_` +tcExpr expr ty | isSigmaTy ty = -- Polymorphic case + tcPolyExpr expr ty `thenTc` \ (expr', lie, _, _, _) -> + returnTc (expr', lie) - returnTc (expr', lie) + | otherwise = -- Monomorphic case + tcMonoExpr expr ty \end{code} + %************************************************************************ %* * -\subsection{Literals} +\subsection{@tcPolyExpr@ typchecks an application} %* * %************************************************************************ -Overloaded literals. - \begin{code} -tcExpr (HsLit (HsInt i)) res_ty - = newOverloadedLit (LiteralOrigin (HsInt i)) - (OverloadedIntegral i) - res_ty `thenNF_Tc` \ stuff -> - returnTc stuff - -tcExpr (HsLit (HsFrac f)) res_ty - = newOverloadedLit (LiteralOrigin (HsFrac f)) - (OverloadedFractional f) - res_ty `thenNF_Tc` \ stuff -> - returnTc stuff - - -tcExpr (HsLit lit@(HsLitLit s)) res_ty - = tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass -> - newDicts (LitLitOrigin (_UNPK_ s)) - [(cCallableClass, [res_ty])] `thenNF_Tc` \ (dicts, _) -> - returnTc (HsLitOut lit res_ty, dicts) -\end{code} +-- tcPolyExpr is like tcMonoExpr, except that the expected type +-- can be a polymorphic one. +tcPolyExpr :: RenamedHsExpr + -> TcType -- Expected type + -> TcM (TcExpr, LIE, -- Generalised expr with expected type, and LIE + TcExpr, TcTauType, LIE) -- Same thing, but instantiated; tau-type returned -Primitive literals: +tcPolyExpr arg expected_arg_ty + = -- Ha! The argument type of the function is a for-all type, + -- An example of rank-2 polymorphism. -\begin{code} -tcExpr (HsLit lit@(HsCharPrim c)) res_ty - = unifyTauTy charPrimTy res_ty `thenTc_` - returnTc (HsLitOut lit charPrimTy, emptyLIE) + -- To ensure that the forall'd type variables don't get unified with each + -- other or any other types, we make fresh copy of the alleged type + tcInstType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_theta, sig_tau) -> + let + free_tvs = tyVarsOfType expected_arg_ty + in + -- Type-check the arg and unify with expected type + tcMonoExpr arg sig_tau `thenTc` \ (arg', lie_arg) -> + + -- Check that the sig_tyvars havn't been constrained + -- The interesting bit here is that we must include the free variables + -- of the expected arg ty. Here's an example: + -- runST (newVar True) + -- Here, if we don't make a check, we'll get a type (ST s (MutVar s Bool)) + -- for (newVar True), with s fresh. Then we unify with the runST's arg type + -- forall s'. ST s' a. That unifies s' with s, and a with MutVar s Bool. + -- So now s' isn't unconstrained because it's linked to a. + -- Conclusion: include the free vars of the expected arg type in the + -- list of "free vars" for the signature check. -tcExpr (HsLit lit@(HsStringPrim s)) res_ty - = unifyTauTy addrPrimTy res_ty `thenTc_` - returnTc (HsLitOut lit addrPrimTy, emptyLIE) + tcExtendGlobalTyVars free_tvs $ + tcAddErrCtxtM (sigCtxt sig_msg sig_tyvars sig_theta sig_tau) $ -tcExpr (HsLit lit@(HsIntPrim i)) res_ty - = unifyTauTy intPrimTy res_ty `thenTc_` - returnTc (HsLitOut lit intPrimTy, emptyLIE) + newDicts SignatureOrigin sig_theta `thenNF_Tc` \ sig_dicts -> + tcSimplifyCheck + (text "the type signature of an expression") + sig_tyvars + sig_dicts lie_arg `thenTc` \ (free_insts, inst_binds) -> -tcExpr (HsLit lit@(HsFloatPrim f)) res_ty - = unifyTauTy floatPrimTy res_ty `thenTc_` - returnTc (HsLitOut lit floatPrimTy, emptyLIE) + checkSigTyVars sig_tyvars free_tvs `thenTc` \ zonked_sig_tyvars -> -tcExpr (HsLit lit@(HsDoublePrim d)) res_ty - = unifyTauTy doublePrimTy res_ty `thenTc_` - returnTc (HsLitOut lit doublePrimTy, emptyLIE) + let + -- This HsLet binds any Insts which came out of the simplification. + -- It's a bit out of place here, but using AbsBind involves inventing + -- a couple of new names which seems worse. + generalised_arg = TyLam zonked_sig_tyvars $ + DictLam (map instToId sig_dicts) $ + mkHsLet inst_binds $ + arg' + in + returnTc ( generalised_arg, free_insts, + arg', sig_tau, lie_arg ) + where + sig_msg = ptext SLIT("When checking an expression type signature") \end{code} -Unoverloaded literals: +%************************************************************************ +%* * +\subsection{The TAUT rules for variables} +%* * +%************************************************************************ \begin{code} -tcExpr (HsLit lit@(HsChar c)) res_ty - = unifyTauTy charTy res_ty `thenTc_` - returnTc (HsLitOut lit charTy, emptyLIE) +tcMonoExpr :: RenamedHsExpr -- Expession to type check + -> TcTauType -- Expected type (could be a type variable) + -> TcM (TcExpr, LIE) + +tcMonoExpr (HsVar name) res_ty + = tcId name `thenNF_Tc` \ (expr', lie, id_ty) -> + unifyTauTy res_ty id_ty `thenTc_` -tcExpr (HsLit lit@(HsString str)) res_ty - = unifyTauTy stringTy res_ty `thenTc_` - returnTc (HsLitOut lit stringTy, emptyLIE) + -- Check that the result type doesn't have any nested for-alls. + -- For example, a "build" on its own is no good; it must be + -- applied to something. + checkTc (isTauTy id_ty) + (lurkingRank2Err name id_ty) `thenTc_` + + returnTc (expr', lie) +\end{code} + +\begin{code} +tcMonoExpr (HsIPVar name) res_ty + = newIPDict (IPOcc name) name res_ty `thenNF_Tc` \ ip -> + returnNF_Tc (HsIPVar (instToId ip), unitLIE ip) \end{code} %************************************************************************ @@ -178,24 +192,18 @@ tcExpr (HsLit lit@(HsString str)) res_ty %************************************************************************ \begin{code} -tcExpr (HsPar expr) res_ty -- preserve parens so printing needn't guess where they go - = tcExpr expr res_ty - --- perform the negate *before* overloading the integer, since the case --- of minBound on Ints fails otherwise. Could be done elsewhere, but --- convenient to do it here. - -tcExpr (NegApp (HsLit (HsInt i)) neg) res_ty - = tcExpr (HsLit (HsInt (-i))) res_ty +tcMonoExpr (HsLit lit) res_ty = tcLit lit res_ty +tcMonoExpr (HsOverLit lit) res_ty = newOverloadedLit (LiteralOrigin lit) lit res_ty +tcMonoExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty -tcExpr (NegApp expr neg) res_ty - = tcExpr (HsApp neg expr) res_ty +tcMonoExpr (NegApp expr neg) res_ty + = tcMonoExpr (HsApp (HsVar neg) expr) res_ty -tcExpr (HsLam match) res_ty - = tcMatchExpected [] res_ty match `thenTc` \ (match',lie) -> +tcMonoExpr (HsLam match) res_ty + = tcMatchLambda match res_ty `thenTc` \ (match',lie) -> returnTc (HsLam match', lie) -tcExpr (HsApp e1 e2) res_ty = accum e1 [e2] +tcMonoExpr (HsApp e1 e2) res_ty = accum e1 [e2] where accum (HsApp e1 e2) args = accum e1 (e2:args) accum fun args @@ -203,7 +211,7 @@ tcExpr (HsApp e1 e2) res_ty = accum e1 [e2] returnTc (foldl HsApp fun' args', lie) -- equivalent to (op e1) e2: -tcExpr (OpApp arg1 op fix arg2) res_ty +tcMonoExpr (OpApp arg1 op fix arg2) res_ty = tcApp op [arg1,arg2] res_ty `thenTc` \ (op', [arg1', arg2'], lie) -> returnTc (OpApp arg1' op' fix arg2', lie) \end{code} @@ -219,7 +227,7 @@ a type error will occur if they aren't. -- or just -- op e -tcExpr in_expr@(SectionL arg op) res_ty +tcMonoExpr in_expr@(SectionL arg op) res_ty = tcApp op [arg] res_ty `thenTc` \ (op', [arg'], lie) -> -- Check that res_ty is a function type @@ -236,12 +244,12 @@ tcExpr in_expr@(SectionL arg op) res_ty -- Right sections, equivalent to \ x -> x op expr, or -- \ x -> op x expr -tcExpr in_expr@(SectionR op expr) res_ty +tcMonoExpr in_expr@(SectionR op expr) res_ty = tcExpr_id op `thenTc` \ (op', lie1, op_ty) -> tcAddErrCtxt (sectionRAppCtxt in_expr) $ split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) -> - tcExpr expr arg2_ty `thenTc` \ (expr',lie2) -> - unifyTauTy (mkFunTy arg1_ty op_res_ty) res_ty `thenTc_` + tcMonoExpr expr arg2_ty `thenTc` \ (expr',lie2) -> + unifyTauTy res_ty (mkFunTy arg1_ty op_res_ty) `thenTc_` returnTc (SectionR op' expr', lie1 `plusLIE` lie2) \end{code} @@ -253,64 +261,62 @@ 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) res_ty +tcMonoExpr (HsCCall lbl args may_gc is_asm ignored_fake_result_ty) res_ty = -- Get the callable and returnable classes. - tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass -> - tcLookupClassByKey cReturnableClassKey `thenNF_Tc` \ cReturnableClass -> - tcLookupTyCon ioTyCon_NAME `thenTc` \ (_,_,ioTyCon) -> - + tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass -> + tcLookupClass cReturnableClassName `thenNF_Tc` \ cReturnableClass -> + tcLookupTyCon ioTyConName `thenNF_Tc` \ ioTyCon -> let new_arg_dict (arg, arg_ty) - = newDicts (CCallOrigin (_UNPK_ lbl) (Just arg)) - [(cCallableClass, [arg_ty])] `thenNF_Tc` \ (arg_dicts, _) -> + = newClassDicts (CCallOrigin (_UNPK_ lbl) (Just arg)) + [(cCallableClass, [arg_ty])] `thenNF_Tc` \ arg_dicts -> returnNF_Tc arg_dicts -- Actually a singleton bag result_origin = CCallOrigin (_UNPK_ lbl) Nothing {- Not an arg -} in -- Arguments - mapNF_Tc (\ _ -> newTyVarTy mkTypeKind) [1..(length args)] `thenNF_Tc` \ ty_vars -> - tcExprs args ty_vars `thenTc` \ (args', args_lie) -> + let n_args = length args + tv_idxs | n_args == 0 = [] + | otherwise = [1..n_args] + in + newTyVarTys (length tv_idxs) openTypeKind `thenNF_Tc` \ arg_tys -> + tcMonoExprs args arg_tys `thenTc` \ (args', args_lie) -> - -- The argument types can be unboxed or boxed; the result - -- type must, however, be boxed since it's an argument to the IO + -- 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 `thenNF_Tc` \ result_ty -> let io_result_ty = mkTyConApp ioTyCon [result_ty] in - case tyConDataCons ioTyCon of { [ioDataCon] -> - unifyTauTy io_result_ty res_ty `thenTc_` + unifyTauTy res_ty io_result_ty `thenTc_` -- Construct the extra insts, which encode the -- constraints on the argument and result types. - mapNF_Tc new_arg_dict (zipEqual "tcExpr:CCall" args ty_vars) `thenNF_Tc` \ ccarg_dicts_s -> - newDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) -> - - returnTc (HsApp (HsVar (RealId ioDataCon) `TyApp` [result_ty]) - (CCall lbl args' may_gc is_asm io_result_ty), - -- do the wrapping in the newtype constructor here - foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie) - } + mapNF_Tc new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s -> + newClassDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ ccres_dict -> + returnTc (HsCCall lbl args' may_gc is_asm io_result_ty, + mkLIE (ccres_dict ++ concat ccarg_dicts_s) `plusLIE` args_lie) \end{code} \begin{code} -tcExpr (HsSCC label expr) res_ty - = tcExpr expr res_ty `thenTc` \ (expr', lie) -> - returnTc (HsSCC label expr', lie) +tcMonoExpr (HsSCC lbl expr) res_ty + = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) -> + returnTc (HsSCC lbl expr', lie) -tcExpr (HsLet binds expr) res_ty +tcMonoExpr (HsLet binds expr) res_ty = tcBindsAndThen combiner binds -- Bindings to check - (tc_expr) `thenTc` \ (expr', lie) -> + tc_expr `thenTc` \ (expr', lie) -> returnTc (expr', lie) where - tc_expr = tcExpr expr res_ty `thenTc` \ (expr', lie) -> + tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) -> returnTc (expr', lie) - combiner is_rec bind expr = HsLet (MonoBind bind [] is_rec) expr + combiner is_rec bind expr = HsLet (mkMonoBind bind [] is_rec) expr -tcExpr in_expr@(HsCase scrut matches src_loc) res_ty +tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty = tcAddSrcLoc src_loc $ tcAddErrCtxt (caseCtxt in_expr) $ @@ -320,70 +326,94 @@ tcExpr in_expr@(HsCase scrut matches src_loc) res_ty -- case (map f) of -- (x:xs) -> ... -- will report that map is applied to too few arguments + -- + -- Not only that, but it's better to check the matches on their + -- own, so that we get the expected results for scoped type variables. + -- f x = case x of + -- (p::a, q::b) -> (q,p) + -- The above should work: the match (p,q) -> (q,p) is polymorphic as + -- claimed by the pattern signatures. But if we typechecked the + -- match with x in scope and x's type as the expected type, we'd be hosed. - tcMatchesCase res_ty matches `thenTc` \ (scrut_ty, matches', lie2) -> + tcMatchesCase matches res_ty `thenTc` \ (scrut_ty, matches', lie2) -> tcAddErrCtxt (caseScrutCtxt scrut) ( - tcExpr scrut scrut_ty + tcMonoExpr scrut scrut_ty ) `thenTc` \ (scrut',lie1) -> returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2) -tcExpr (HsIf pred b1 b2 src_loc) res_ty +tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty = tcAddSrcLoc src_loc $ tcAddErrCtxt (predCtxt pred) ( - tcExpr pred boolTy ) `thenTc` \ (pred',lie1) -> + tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) -> - tcExpr b1 res_ty `thenTc` \ (b1',lie2) -> - tcExpr b2 res_ty `thenTc` \ (b2',lie3) -> + tcMonoExpr b1 res_ty `thenTc` \ (b1',lie2) -> + tcMonoExpr b2 res_ty `thenTc` \ (b2',lie3) -> returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3)) \end{code} \begin{code} -tcExpr expr@(HsDo do_or_lc stmts src_loc) res_ty +tcMonoExpr expr@(HsDo do_or_lc stmts src_loc) res_ty = tcDoStmts do_or_lc stmts src_loc res_ty \end{code} \begin{code} -tcExpr in_expr@(ExplicitList exprs) res_ty -- Non-empty list +tcMonoExpr in_expr@(ExplicitList exprs) res_ty -- Non-empty list = unifyListTy res_ty `thenTc` \ elt_ty -> mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) -> returnTc (ExplicitListOut elt_ty exprs', plusLIEs lies) where tc_elt elt_ty expr = tcAddErrCtxt (listCtxt expr) $ - tcExpr expr elt_ty + tcMonoExpr expr elt_ty -tcExpr (ExplicitTuple exprs) res_ty - = unifyTupleTy (length exprs) res_ty `thenTc` \ arg_tys -> - mapAndUnzipTc (\ (expr, arg_ty) -> tcExpr expr arg_ty) +tcMonoExpr (ExplicitTuple exprs boxity) res_ty + = unifyTupleTy boxity (length exprs) res_ty `thenTc` \ arg_tys -> + mapAndUnzipTc (\ (expr, arg_ty) -> tcMonoExpr expr arg_ty) (exprs `zip` arg_tys) -- we know they're of equal length. - `thenTc` \ (exprs', lies) -> - returnTc (ExplicitTuple exprs', plusLIEs lies) + `thenTc` \ (exprs', lies) -> + returnTc (ExplicitTuple exprs' boxity, plusLIEs lies) -tcExpr (RecordCon con_name _ rbinds) res_ty - = tcLookupGlobalValue con_name `thenNF_Tc` \ con_id -> +tcMonoExpr expr@(RecordCon con_name rbinds) res_ty + = tcAddErrCtxt (recordConCtxt expr) $ tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) -> let (_, record_ty) = splitFunTys con_tau + (tycon, ty_args, _) = splitAlgTyConApp record_ty in - -- Con is syntactically constrained to be a data constructor ASSERT( maybeToBool (splitAlgTyConApp_maybe record_ty ) ) unifyTauTy res_ty record_ty `thenTc_` -- Check that the record bindings match the constructor + -- con_name is syntactically constrained to be a data constructor + tcLookupDataCon con_name `thenTc` \ data_con -> let - bad_fields = badFields rbinds con_id + bad_fields = badFields rbinds data_con in - checkTc (null bad_fields) (badFieldsCon con_id bad_fields) `thenTc_` + if not (null bad_fields) then + mapNF_Tc (addErrTc . badFieldCon con_name) bad_fields `thenNF_Tc_` + failTc -- Fail now, because tcRecordBinds will crash on a bad field + 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 (RealId con_id) con_expr rbinds', con_lie `plusLIE` rbinds_lie) + tcRecordBinds tycon ty_args rbinds `thenTc` \ (rbinds', rbinds_lie) -> + + let + missing_s_fields = missingStrictFields rbinds data_con + in + checkTcM (null missing_s_fields) + (mapNF_Tc (addErrTc . missingStrictFieldCon con_name) missing_s_fields `thenNF_Tc_` + returnNF_Tc ()) `thenNF_Tc_` + let + missing_fields = missingFields rbinds data_con + in + doptsTc Opt_WarnMissingFields `thenNF_Tc` \ warn -> + checkTcM (not (warn && not (null missing_fields))) + (mapNF_Tc ((warnTc True) . missingFieldCon con_name) missing_fields `thenNF_Tc_` + returnNF_Tc ()) `thenNF_Tc_` + returnTc (RecordConOut data_con con_expr rbinds', con_lie `plusLIE` rbinds_lie) -- The main complication with RecordUpd is that we need to explicitly -- handle the *non-updated* fields. Consider: @@ -411,32 +441,44 @@ tcExpr (RecordCon con_name _ rbinds) res_ty -- -- All this is done in STEP 4 below. -tcExpr (RecordUpd record_expr rbinds) res_ty - = tcAddErrCtxt recordUpdCtxt $ +tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty + = tcAddErrCtxt (recordUpdCtxt expr) $ - -- STEP 1 - -- Figure out the tycon and data cons from the first field name + -- STEP 0 + -- Check that the field names are really field names ASSERT( not (null rbinds) ) let - ((first_field_name, _, _) : rest) = rbinds + field_names = [field_name | (field_name, _, _) <- rbinds] 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 -> failWithTc (notSelector first_field_name) - ) `thenTc` \ sel_id -> + mapNF_Tc tcLookupGlobal_maybe field_names `thenNF_Tc` \ maybe_sel_ids -> let - (_, tau) = splitForAllTys (idType sel_id) + bad_guys = [ addErrTc (notSelector field_name) + | (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids, + case maybe_sel_id of + Just (AnId sel_id) -> not (isRecordSelector sel_id) + other -> True + ] + in + checkTcM (null bad_guys) (listNF_Tc bad_guys `thenNF_Tc_` failTc) `thenTc_` + + -- STEP 1 + -- Figure out the tycon and data cons from the first field name + let + (Just (AnId sel_id) : _) = maybe_sel_ids + (_, _, tau) = splitSigmaTy (idType sel_id) -- Selectors can be overloaded + -- when the data type has a context Just (data_ty, _) = splitFunTy_maybe tau -- Must succeed since sel_id is a selector - (tycon, _, data_cons) = splitAlgTyConApp data_ty - (con_tyvars, theta, _, _, _, _) = dataConSig (head data_cons) + (tycon, _, data_cons) = splitAlgTyConApp data_ty + (con_tyvars, _, _, _, _, _) = dataConSig (head data_cons) in tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) -> -- 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_` + -- STEP 3 -- Typecheck the update bindings. -- (Do this after checking for bad fields in case there's a field that @@ -445,7 +487,7 @@ tcExpr (RecordUpd record_expr rbinds) res_ty result_record_ty = mkTyConApp tycon result_inst_tys in unifyTauTy res_ty result_record_ty `thenTc_` - tcRecordBinds result_record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) -> + tcRecordBinds tycon result_inst_tys rbinds `thenTc` \ (rbinds', rbinds_lie) -> -- STEP 4 -- Use the un-updated fields to find a vector of booleans saying @@ -454,7 +496,7 @@ tcExpr (RecordUpd record_expr rbinds) res_ty -- WARNING: this code assumes that all data_cons in a common tycon -- have FieldLabels abstracted over the same tyvars. let - upd_field_lbls = [recordSelectorFieldLabel sel_id | (RealId sel_id, _, _) <- rbinds'] + upd_field_lbls = [recordSelectorFieldLabel sel_id | (sel_id, _, _) <- rbinds'] con_field_lbls_s = map dataConFieldLabels data_cons -- A constructor is only relevant to this process if @@ -466,8 +508,8 @@ tcExpr (RecordUpd record_expr rbinds) res_ty 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 = returnNF_Tc 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 -> @@ -476,7 +518,7 @@ tcExpr (RecordUpd record_expr rbinds) res_ty let record_ty = mkTyConApp tycon inst_tys in - tcExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) -> + tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) -> -- STEP 6 -- Figure out the LIE we need. We have to generate some @@ -489,65 +531,62 @@ tcExpr (RecordUpd record_expr rbinds) res_ty -- union the ones that could participate in the update. let (tyvars, theta, _, _, _, _) = dataConSig (head data_cons) - inst_env = zipTyVarEnv tyvars result_inst_tys + inst_env = mkTopTyVarSubst tyvars result_inst_tys + theta' = substClasses inst_env theta in - tcInstTheta inst_env theta `thenNF_Tc` \ theta' -> - newDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) -> + newClassDicts RecordUpdOrigin theta' `thenNF_Tc` \ dicts -> -- Phew! - returnTc (RecordUpdOut record_expr' result_record_ty dicts rbinds', - con_lie `plusLIE` record_lie `plusLIE` rbinds_lie) + returnTc (RecordUpdOut record_expr' result_record_ty (map instToId dicts) rbinds', + mkLIE dicts `plusLIE` record_lie `plusLIE` rbinds_lie) -tcExpr (ArithSeqIn seq@(From expr)) res_ty - = unifyListTy res_ty `thenTc` \ elt_ty -> - tcExpr expr elt_ty `thenTc` \ (expr', lie1) -> +tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty + = unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) -> - tcLookupGlobalValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id -> + tcLookupGlobalId enumFromName `thenNF_Tc` \ sel_id -> newMethod (ArithSeqOrigin seq) - (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie2, enum_from_id) -> + sel_id [elt_ty] `thenNF_Tc` \ enum_from -> - returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'), - lie1 `plusLIE` lie2) + returnTc (ArithSeqOut (HsVar (instToId enum_from)) (From expr'), + lie1 `plusLIE` unitLIE enum_from) -tcExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty +tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty = tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenTc` \ elt_ty -> - tcExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> - tcExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> - tcLookupGlobalValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie3, enum_from_then_id) -> + unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> + tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> + tcLookupGlobalId enumFromThenName `thenNF_Tc` \ sel_id -> + newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_then -> - returnTc (ArithSeqOut (HsVar enum_from_then_id) - (FromThen expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` lie3) + returnTc (ArithSeqOut (HsVar (instToId enum_from_then)) + (FromThen expr1' expr2'), + lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_then) -tcExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty +tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty = tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenTc` \ elt_ty -> - tcExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> - tcExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> - tcLookupGlobalValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie3, enum_from_to_id) -> + unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> + tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> + tcLookupGlobalId enumFromToName `thenNF_Tc` \ sel_id -> + newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_to -> - returnTc (ArithSeqOut (HsVar enum_from_to_id) + returnTc (ArithSeqOut (HsVar (instToId enum_from_to)) (FromTo expr1' expr2'), - lie1 `plusLIE` lie2 `plusLIE` lie3) + lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_to) -tcExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty +tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty = tcAddErrCtxt (arithSeqCtxt in_expr) $ - unifyListTy res_ty `thenTc` \ elt_ty -> - tcExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> - tcExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> - tcExpr expr3 elt_ty `thenTc` \ (expr3',lie3) -> - tcLookupGlobalValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id -> - newMethod (ArithSeqOrigin seq) - (RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie4, eft_id) -> - - returnTc (ArithSeqOut (HsVar eft_id) - (FromThenTo expr1' expr2' expr3'), - lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4) + unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> + tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> + tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) -> + tcLookupGlobalId enumFromThenToName `thenNF_Tc` \ sel_id -> + newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ eft -> + + returnTc (ArithSeqOut (HsVar (instToId eft)) + (FromThenTo expr1' expr2' expr3'), + lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft) \end{code} %************************************************************************ @@ -557,63 +596,67 @@ tcExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty %************************************************************************ \begin{code} -tcExpr in_expr@(ExprWithTySig expr poly_ty) res_ty +tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty = tcSetErrCtxt (exprSigCtxt in_expr) $ - tcHsType poly_ty `thenTc` \ sigma_sig -> - - -- Check the tau-type part - tcInstSigType sigma_sig `thenNF_Tc` \ sigma_sig' -> - let - (sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig' - in - - -- Type check the expression, expecting the signature type - tcExtendGlobalTyVars sig_tyvars' ( - tcExpr expr sig_tau' - ) `thenTc` \ (texpr, lie) -> - - -- Check the type variables of the signature, - -- *after* typechecking the expression - checkSigTyVars sig_tyvars' sig_tau' `thenTc` \ zonked_sig_tyvars -> - - -- Check overloading constraints - newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (sig_dicts, _) -> - tcAddErrCtxtM (sigThetaCtxt sig_dicts) ( - tcSimplifyAndCheck - (text "expr ty sig") - (mkTyVarSet zonked_sig_tyvars) - sig_dicts lie - ) `thenTc_` - - -- Now match the signature type with res_ty. - -- We must not do this earlier, because res_ty might well - -- mention variables free in the environment, and we'd get - -- bogus complaints about not being able to for-all the - -- sig_tyvars - unifyTauTy sig_tau' res_ty `thenTc_` - - -- If everything is ok, return the stuff unchanged, except for - -- the effect of any substutions etc. We simply discard the - -- result of the tcSimplifyAndCheck, except for any default - -- resolution it may have done, which is recorded in the - -- substitution. - returnTc (texpr, lie) + tcHsSigType poly_ty `thenTc` \ sig_tc_ty -> + + if not (isSigmaTy sig_tc_ty) then + -- Easy case + unifyTauTy sig_tc_ty res_ty `thenTc_` + tcMonoExpr expr sig_tc_ty + + else -- Signature is polymorphic + tcPolyExpr expr sig_tc_ty `thenTc` \ (_, _, expr, expr_ty, lie) -> + + -- Now match the signature type with res_ty. + -- We must not do this earlier, because res_ty might well + -- mention variables free in the environment, and we'd get + -- bogus complaints about not being able to for-all the + -- sig_tyvars + unifyTauTy res_ty expr_ty `thenTc_` + + -- If everything is ok, return the stuff unchanged, except for + -- the effect of any substutions etc. We simply discard the + -- result of the tcSimplifyCheck (inside tcPolyExpr), except for any default + -- resolution it may have done, which is recorded in the + -- substitution. + returnTc (expr, lie) +\end{code} +Implicit Parameter bindings. + +\begin{code} +tcMonoExpr (HsWith expr binds) res_ty + = tcMonoExpr expr res_ty `thenTc` \ (expr', expr_lie) -> + mapAndUnzipTc tcIPBind binds `thenTc` \ (pairs, bind_lies) -> + tcSimplifyIPs (map fst binds) expr_lie `thenTc` \ (expr_lie', dict_binds) -> + let + binds' = [(instToId ip, rhs) | (ip,rhs) <- pairs] + expr'' = HsLet (mkMonoBind dict_binds [] Recursive) expr' + in + returnTc (HsWith expr'' binds', expr_lie' `plusLIE` plusLIEs bind_lies) + +tcIPBind (name, expr) + = newTyVarTy openTypeKind `thenTc` \ ty -> + tcGetSrcLoc `thenTc` \ loc -> + newIPDict (IPBind name) name ty `thenNF_Tc` \ ip -> + tcMonoExpr expr ty `thenTc` \ (expr', lie) -> + returnTc ((ip, expr'), lie) \end{code} Typecheck expression which in most cases will be an Id. \begin{code} tcExpr_id :: RenamedHsExpr - -> TcM s (TcExpr s, - LIE s, - TcType s) + -> TcM (TcExpr, + LIE, + TcType) tcExpr_id id_expr = case id_expr of - HsVar name -> tcId name `thenNF_Tc` \ stuff -> + HsVar name -> tcId name `thenNF_Tc` \ stuff -> returnTc stuff - other -> newTyVarTy mkTypeKind `thenNF_Tc` \ id_ty -> - tcExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) -> + other -> newTyVarTy openTypeKind `thenNF_Tc` \ id_ty -> + tcMonoExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) -> returnTc (id_expr', lie_id, id_ty) \end{code} @@ -625,10 +668,10 @@ tcExpr_id id_expr \begin{code} -tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args - -> TcType s -- Expected result type of application - -> TcM s (TcExpr s, [TcExpr s], -- Translated fun and args - LIE s) +tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args + -> TcType -- Expected result type of application + -> TcM (TcExpr, [TcExpr], -- Translated fun and args + LIE) tcApp fun args res_ty = -- First type-check the function @@ -651,7 +694,7 @@ tcApp fun 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 actual_result_ty) - (lurkingRank2Err fun fun_ty) `thenTc_` + (lurkingRank2Err fun actual_result_ty) `thenTc_` returnTc (fun', args', lie_fun `plusLIE` plusLIEs lie_args_s) @@ -659,23 +702,26 @@ tcApp fun args res_ty -- If an error happens we try to figure out whether the -- function has been given too many or too few arguments, -- and say so -checkArgsCtxt fun args expected_res_ty actual_res_ty +checkArgsCtxt fun args expected_res_ty actual_res_ty tidy_env = zonkTcType expected_res_ty `thenNF_Tc` \ exp_ty' -> zonkTcType actual_res_ty `thenNF_Tc` \ act_ty' -> let - (exp_args, _) = splitFunTys exp_ty' - (act_args, _) = splitFunTys act_ty' + (env1, exp_ty'') = tidyOpenType tidy_env exp_ty' + (env2, act_ty'') = tidyOpenType env1 act_ty' + (exp_args, _) = splitFunTys exp_ty'' + (act_args, _) = splitFunTys act_ty'' + message | length exp_args < length act_args = wrongArgsCtxt "too few" fun args | length exp_args > length act_args = wrongArgsCtxt "too many" fun args | otherwise = appCtxt fun args in - returnNF_Tc message + returnNF_Tc (env2, message) -split_fun_ty :: TcType s -- The type of the function +split_fun_ty :: TcType -- The type of the function -> Int -- Number of arguments - -> TcM s ([TcType s], -- Function argument types - TcType s) -- Function result types + -> TcM ([TcType], -- Function argument types + TcType) -- Function result types split_fun_ty fun_ty 0 = returnTc ([], fun_ty) @@ -689,74 +735,15 @@ split_fun_ty fun_ty n \begin{code} tcArg :: RenamedHsExpr -- The function (for error messages) - -> (RenamedHsExpr, TcType s, Int) -- Actual argument and expected arg type - -> TcM s (TcExpr s, LIE s) -- Resulting argument and LIE + -> (RenamedHsExpr, TcType, Int) -- Actual argument and expected arg type + -> TcM (TcExpr, LIE) -- Resulting argument and LIE tcArg the_fun (arg, expected_arg_ty, arg_no) = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $ - tcPolyExpr arg expected_arg_ty - - --- tcPolyExpr is like tcExpr, except that the expected type --- can be a polymorphic one. -tcPolyExpr arg expected_arg_ty - | not (maybeToBool (splitForAllTy_maybe expected_arg_ty)) - = -- The ordinary, non-rank-2 polymorphic case tcExpr arg expected_arg_ty - - | 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 - -- Type-check the arg and unify with expected type - tcExpr arg sig_tau `thenTc` \ (arg', lie_arg) -> - - -- 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 (tyVarSetToList (tyVarsOfType expected_arg_ty)) $ - - checkSigTyVars sig_tyvars sig_tau `thenTc` \ zonked_sig_tyvars -> - newDicts Rank2Origin sig_theta `thenNF_Tc` \ (sig_dicts, dict_ids) -> - -- ToDo: better origin - - tcAddErrCtxtM (sigThetaCtxt sig_dicts) $ - tcSimplifyAndCheck (text "rank2") - (mkTyVarSet zonked_sig_tyvars) - sig_dicts 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 zonked_sig_tyvars $ - DictLam dict_ids $ - HsLet (MonoBind inst_binds [] Recursive) - arg' - , free_insts - ) \end{code} + %************************************************************************ %* * \subsection{@tcId@ typchecks an identifier occurrence} @@ -764,46 +751,14 @@ tcPolyExpr arg expected_arg_ty %************************************************************************ \begin{code} -tcId :: Name -> NF_TcM s (TcExpr s, LIE s, TcType s) +tcId :: Name -> NF_TcM (TcExpr, LIE, TcType) 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 emptyTyVarEnv (idType id) `thenNF_Tc` \ inst_ty -> - let - (tyvars, rho) = splitForAllTys 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 theta tau `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 + tcLookup name `thenNF_Tc` \ thing -> + case thing of + ATcId tc_id -> tcInstId tc_id + AGlobal (AnId id) -> tcInstId id \end{code} %************************************************************************ @@ -818,20 +773,21 @@ tcDoStmts do_or_lc stmts src_loc res_ty -- 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) -> - unifyTauTy result_ty res_ty `thenTc_` + -- If it's a comprehension we're dealing with, + -- force it to be a list comprehension. + -- (as of Haskell 98, monad comprehensions are no more.) + (case do_or_lc of + ListComp -> unifyListTy res_ty `thenTc` \ elt_ty -> + returnNF_Tc (mkTyConTy listTyCon, (mkListTy, elt_ty)) + + _ -> newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenNF_Tc` \ m_ty -> + newTyVarTy liftedTypeKind `thenNF_Tc` \ elt_ty -> + unifyTauTy res_ty (mkAppTy m_ty elt_ty) `thenTc_` + returnNF_Tc (m_ty, (mkAppTy m_ty, elt_ty)) + ) `thenNF_Tc` \ (tc_ty, m_ty) -> + + tcStmts do_or_lc m_ty stmts `thenTc` \ (stmts', stmts_lie) -> -- Build the then and zero methods in case we need them -- It's important that "then" and "return" appear just once in the final LIE, @@ -841,108 +797,21 @@ tcDoStmts do_or_lc stmts src_loc res_ty -- 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) -> + tcLookupGlobalId returnMName `thenNF_Tc` \ return_sel_id -> + tcLookupGlobalId thenMName `thenNF_Tc` \ then_sel_id -> + tcLookupGlobalId failMName `thenNF_Tc` \ fail_sel_id -> + newMethod DoOrigin return_sel_id [tc_ty] `thenNF_Tc` \ return_inst -> + newMethod DoOrigin then_sel_id [tc_ty] `thenNF_Tc` \ then_inst -> + newMethod DoOrigin fail_sel_id [tc_ty] `thenNF_Tc` \ fail_inst -> let - monad_lie = 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 + monad_lie = mkLIE [return_inst, then_inst, fail_inst] in - returnTc (HsDoOut do_or_lc stmts' return_id then_id zero_id res_ty src_loc, - final_lie `plusLIE` monad_lie) - + returnTc (HsDoOut do_or_lc stmts' + (instToId return_inst) (instToId then_inst) (instToId fail_inst) + res_ty src_loc, + stmts_lie `plusLIE` monad_lie) \end{code} -\begin{code} -tcStmt :: (RenamedHsExpr -> TcType s -> TcM s (TcExpr s, LIE 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; Guard -> True } ) - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty -> - tc_expr exp exp_ty `thenTc` \ (exp', exp_lie) -> - 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; Guard -> True } ) - newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty -> - tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - tc_expr exp boolTy `thenTc` \ (exp', exp_lie) -> - 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; Guard -> False } ) - newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty -> - tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - newTyVarTy mkTypeKind `thenNF_Tc` \ tau -> - let - -- exp has type (m tau) for some tau (doesn't matter what) - exp_ty = m tau - in - tc_expr exp exp_ty `thenTc` \ (exp', exp_lie) -> - 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 (m pat_ty) `thenTc` \ (exp', exp_lie) -> - - -- 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' -\end{code} %************************************************************************ %* * @@ -952,55 +821,51 @@ 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 + :: TyCon -- Type constructor for the record + -> [TcType] -- Args of this type constructor -> RenamedRecordBinds - -> TcM s (TcRecordBinds s, LIE s) + -> TcM (TcRecordBinds, LIE) -tcRecordBinds expected_record_ty rbinds +tcRecordBinds tycon ty_args rbinds = mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) -> returnTc (rbinds', plusLIEs lies) where - do_bind (field_label, rhs, pun_flag) - = tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id -> + tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args + + do_bind (field_lbl_name, rhs, pun_flag) + = tcLookupGlobalId field_lbl_name `thenNF_Tc` \ 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) -> + tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) -> - -- Record selectors all have type - -- forall a1..an. T a1 .. an -> tau - ASSERT( maybeToBool (splitFunTy_maybe tau) ) - let - -- Selector must have type RecordType -> FieldType - Just (record_ty, field_ty) = splitFunTy_maybe tau - in - unifyTauTy expected_record_ty record_ty `thenTc_` - tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie) -> - returnTc ((RealId sel_id, rhs', pun_flag), lie) + returnTc ((sel_id, rhs', pun_flag), lie) badFields rbinds data_con = [field_name | (field_name, _, _) <- rbinds, @@ -1008,34 +873,88 @@ badFields rbinds data_con ] where field_names = map fieldLabelName (dataConFieldLabels data_con) + +missingStrictFields rbinds data_con + = [ fn | fn <- strict_field_names, + not (fn `elem` field_names_used) + ] + where + field_names_used = [ field_name | (field_name, _, _) <- rbinds ] + strict_field_names = mapMaybe isStrict field_info + + isStrict (fl, MarkedStrict) = Just (fieldLabelName fl) + isStrict _ = Nothing + + field_info = zip (dataConFieldLabels data_con) + (dataConStrictMarks data_con) + +missingFields rbinds data_con + = [ fn | fn <- non_strict_field_names, not (fn `elem` field_names_used) ] + where + field_names_used = [ field_name | (field_name, _, _) <- rbinds ] + + -- missing strict fields have already been flagged as + -- being so, so leave them out here. + non_strict_field_names = mapMaybe isn'tStrict field_info + + isn'tStrict (fl, MarkedStrict) = Nothing + isn'tStrict (fl, _) = Just (fieldLabelName fl) + + field_info = zip (dataConFieldLabels data_con) + (dataConStrictMarks data_con) + \end{code} %************************************************************************ %* * -\subsection{@tcExprs@ typechecks a {\em list} of expressions} +\subsection{@tcMonoExprs@ typechecks a {\em list} of expressions} %* * %************************************************************************ \begin{code} -tcExprs :: [RenamedHsExpr] -> [TcType s] -> TcM s ([TcExpr s], LIE s) +tcMonoExprs :: [RenamedHsExpr] -> [TcType] -> TcM ([TcExpr], LIE) -tcExprs [] [] = returnTc ([], emptyLIE) -tcExprs (expr:exprs) (ty:tys) - = tcExpr expr ty `thenTc` \ (expr', lie1) -> - tcExprs exprs tys `thenTc` \ (exprs', lie2) -> +tcMonoExprs [] [] = returnTc ([], emptyLIE) +tcMonoExprs (expr:exprs) (ty:tys) + = tcMonoExpr expr ty `thenTc` \ (expr', lie1) -> + tcMonoExprs exprs tys `thenTc` \ (exprs', lie2) -> returnTc (expr':exprs', lie1 `plusLIE` lie2) \end{code} -% ================================================= +%************************************************************************ +%* * +\subsection{Literals} +%* * +%************************************************************************ + +Overloaded literals. + +\begin{code} +tcLit :: HsLit -> TcType -> TcM (TcExpr, LIE) +tcLit (HsLitLit s _) res_ty + = tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass -> + newClassDicts (LitLitOrigin (_UNPK_ s)) + [(cCallableClass,[res_ty])] `thenNF_Tc` \ dicts -> + returnTc (HsLit (HsLitLit s res_ty), mkLIE dicts) + +tcLit lit res_ty + = unifyTauTy res_ty (simpleHsLitTy lit) `thenTc_` + returnTc (HsLit lit, emptyLIE) +\end{code} + -Errors and contexts -~~~~~~~~~~~~~~~~~~~ +%************************************************************************ +%* * +\subsection{Errors and contexts} +%* * +%************************************************************************ Mini-utils: + \begin{code} pp_nest_hang :: String -> SDoc -> SDoc -pp_nest_hang label stuff = nest 2 (hang (text label) 4 stuff) +pp_nest_hang lbl stuff = nest 2 (hang (text lbl) 4 stuff) \end{code} Boring and alphabetical: @@ -1070,35 +989,23 @@ funAppCtxt fun arg arg_no quotes (ppr fun) <> text ", namely"]) 4 (quotes (ppr arg)) -stmtCtxt do_or_lc stmt - = hang (ptext SLIT("In a") <+> whatever <> colon) - 4 (ppr stmt) - where - whatever = case do_or_lc of - ListComp -> ptext SLIT("list-comprehension qualifier") - DoStmt -> ptext SLIT("do statement") - Guard -> ptext SLIT("guard") - wrongArgsCtxt too_many_or_few fun args - = hang (ptext SLIT("Probable cause:") <+> ppr fun + = 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 (ppr the_app) + 4 (parens (ppr the_app)) where the_app = foldl HsApp fun args -- Used in error messages appCtxt fun args - = ptext SLIT("In the application") <+> (ppr the_app) + = ptext SLIT("In the application") <+> quotes (ppr the_app) where the_app = foldl HsApp fun args -- Used in error messages lurkingRank2Err fun fun_ty = hang (hsep [ptext SLIT("Illegal use of"), quotes (ppr fun)]) 4 (vcat [ptext SLIT("It is applied to too few arguments"), - ptext SLIT("so that the result type has for-alls in it")]) - -rank2ArgCtxt arg expected_arg_ty - = ptext SLIT("In a polymorphic function argument:") <+> ppr arg + ptext SLIT("so that the result type has for-alls in it:") <+> ppr fun_ty]) badFieldsUpd rbinds = hang (ptext SLIT("No constructor has all these fields:")) @@ -1106,12 +1013,19 @@ badFieldsUpd rbinds where fields = [field | (field, _, _) <- rbinds] -recordUpdCtxt = ptext SLIT("In a record update construct") - -badFieldsCon con fields - = hsep [ptext SLIT("Constructor"), ppr con, - ptext SLIT("does not have field(s):"), pprQuotedList fields] +recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr +recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr notSelector field = hsep [quotes (ppr field), ptext SLIT("is not a record selector")] + +missingStrictFieldCon :: Name -> Name -> SDoc +missingStrictFieldCon con field + = hsep [ptext SLIT("Constructor") <+> quotes (ppr con), + ptext SLIT("does not have the required strict field"), quotes (ppr field)] + +missingFieldCon :: Name -> Name -> SDoc +missingFieldCon con field + = hsep [ptext SLIT("Field") <+> quotes (ppr field), + ptext SLIT("is not initialised")] \end{code}