X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=006983ddf4cdb59297089547c1cc19d662e11df1;hb=b4775e5e760111e2d71fba3c44882dce390edfb2;hp=15b67291bdaab4944394da158b4b624e430e7e34;hpb=10521d8418fd3a1cf32882718b5bd28992db36fd;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 15b6729..006983d 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -1,163 +1,188 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % -\section[TcExpr]{TcExpr} +\section[TcExpr]{Typecheck an expression} \begin{code} +module TcExpr ( tcApp, tcExpr, tcMonoExpr, tcPolyExpr, tcId ) where + #include "HsVersions.h" -module TcExpr ( - tcExpr -#ifdef DPH - , tcExprs -#endif - ) where - -import TcMonad -- typechecking monad machinery -import TcMonadFns ( newPolyTyVarTy, newOpenTyVarTy, - newDict, newMethod, newOverloadedLit, - applyTcSubstAndCollectTyVars, - mkIdsWithPolyTyVarTys +import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), + HsMatchContext(..), mkMonoBind ) -import AbsSyn -- the stuff being typechecked +import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds ) +import TcHsSyn ( TcExpr, TcRecordBinds, mkHsLet ) +import TcMonad +import BasicTypes ( RecFlag(..) ) -import AbsPrel ( intPrimTy, charPrimTy, doublePrimTy, - floatPrimTy, addrPrimTy, addrTy, - boolTy, charTy, stringTy, mkFunTy, mkListTy, - mkTupleTy, mkPrimIoTy -#ifdef DPH - ,mkProcessorTy, mkPodTy,toPodId, - processorClass,pidClass -#endif {- Data Parallel Haskell -} +import Inst ( InstOrigin(..), + LIE, mkLIE, emptyLIE, unitLIE, plusLIE, plusLIEs, + newOverloadedLit, newMethod, newIPDict, + newDicts, + instToId, tcInstId + ) +import TcBinds ( tcBindsAndThen ) +import TcEnv ( tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe, + tcLookupTyCon, tcLookupDataCon, tcLookupId, + tcExtendGlobalTyVars, tcLookupSyntaxName + ) +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 FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon ) +import Id ( idType, recordSelectorFieldLabel, isRecordSelector ) +import DataCon ( dataConFieldLabels, dataConSig, + dataConStrictMarks ) -import AbsUniType -import E -import CE ( lookupCE ) - -import Errors -import GenSpecEtc ( checkSigTyVars ) -import Id ( mkInstId, getIdUniType, Id ) -import Inst -import LIE ( nullLIE, unitLIE, plusLIE, unMkLIE, mkLIE, LIE ) -import ListSetOps ( unionLists ) -import Maybes ( Maybe(..) ) -import TVE ( nullTVE, TVE(..) ) -import Spec ( specId, specTy ) -import TcBinds ( tcLocalBindsAndThen ) -import TcMatches ( tcMatchesCase, tcMatch ) -import TcPolyType ( tcPolyType ) -import TcQuals ( tcQuals ) -import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 ) -#ifdef DPH -import TcParQuals -#endif {- Data Parallel Haskell -} -import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists ) -import UniqFM ( emptyUFM ) -- profiling, pragmas only -import Unique -- *Key stuff +import Demand ( isMarkedStrict ) +import Name ( Name ) +import Type ( mkFunTy, mkAppTy, mkTyConTy, + splitFunTy_maybe, splitFunTys, + mkTyConApp, splitSigmaTy, mkClassPred, + isTauTy, tyVarsOfType, tyVarsOfTypes, + isSigmaTy, splitAlgTyConApp, splitAlgTyConApp_maybe, + liftedTypeKind, openTypeKind, mkArrowKind, + tidyOpenType + ) +import TyCon ( TyCon, tyConTyVars ) +import Subst ( mkTopTyVarSubst, substTheta, substTy ) +import VarSet ( elemVarSet ) +import TysWiredIn ( boolTy, mkListTy, listTyCon ) +import TcUnify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy ) +import PrelNames ( cCallableClassName, + cReturnableClassName, + enumFromName, enumFromThenName, negateName, + enumFromToName, enumFromThenToName, + thenMName, failMName, returnMName, ioTyConName + ) +import Outputable +import Maybes ( maybeToBool ) +import ListSetOps ( minusList ) import Util +import CmdLineOpts +import HscTypes ( TyThing(..) ) -tcExpr :: E -> RenamedExpr -> TcM (TypecheckedExpr, LIE, UniType) \end{code} %************************************************************************ %* * -\subsection{The TAUT rules for variables} +\subsection{Main wrappers} %* * %************************************************************************ \begin{code} -tcExpr e (Var name) - = specId (lookupE_Value e name) `thenNF_Tc` \ stuff@(expr, lie, ty) -> +tcExpr :: RenamedHsExpr -- Expession to type check + -> TcType -- Expected type (could be a polytpye) + -> TcM (TcExpr, LIE) - -- Check that there's no lurking rank-2 polymorphism - -- isTauTy is over-paranoid, because we don't expect - -- any submerged polymorphism other than rank-2 polymorphism +tcExpr expr ty | isSigmaTy ty = -- Polymorphic case + tcPolyExpr expr ty `thenTc` \ (expr', lie, _, _, _) -> + returnTc (expr', lie) - getSrcLocTc `thenNF_Tc` \ loc -> - checkTc (not (isTauTy ty)) (lurkingRank2Err name ty loc) `thenTc_` - - returnTc stuff + | otherwise = -- Monomorphic case + tcMonoExpr expr ty \end{code} + %************************************************************************ %* * -\subsection{Literals} +\subsection{@tcPolyExpr@ typchecks an application} %* * %************************************************************************ -Overloaded literals. - \begin{code} -tcExpr e (Lit lit@(IntLit i)) - = getSrcLocTc `thenNF_Tc` \ loc -> - newPolyTyVarTy `thenNF_Tc` \ ty -> +-- tcPolyExpr is like tcMonoExpr, except that the expected type +-- can be a polymorphic one. +tcPolyExpr :: RenamedHsExpr + -> TcType -- Expected type + -> TcM (TcExpr, LIE, -- Generalised expr with expected type, and LIE + TcExpr, TcTauType, LIE) -- Same thing, but instantiated; tau-type returned + +tcPolyExpr arg expected_arg_ty + = -- Ha! The argument type of the function is a for-all type, + -- An example of rank-2 polymorphism. + + -- To ensure that the forall'd type variables don't get unified with each + -- other or any other types, we make fresh copy of the alleged type + tcInstType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_theta, sig_tau) -> let - from_int = lookupE_ClassOpByKey e numClassKey SLIT("fromInt") - from_integer = lookupE_ClassOpByKey e numClassKey SLIT("fromInteger") + free_tvs = tyVarsOfType expected_arg_ty in - newOverloadedLit (LiteralOrigin lit loc) - (OverloadedIntegral i from_int from_integer) - ty - `thenNF_Tc` \ over_lit -> + -- Type-check the arg and unify with expected type + tcMonoExpr arg sig_tau `thenTc` \ (arg', lie_arg) -> - returnTc (Var (mkInstId over_lit), unitLIE over_lit, ty) + -- 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 e (Lit lit@(FracLit f)) - = getSrcLocTc `thenNF_Tc` \ loc -> - newPolyTyVarTy `thenNF_Tc` \ ty -> - let - from_rational = lookupE_ClassOpByKey e fractionalClassKey SLIT("fromRational") - in - newOverloadedLit (LiteralOrigin lit loc) - (OverloadedFractional f from_rational) - ty - `thenNF_Tc` \ over_lit -> + tcExtendGlobalTyVars free_tvs $ + tcAddErrCtxtM (sigCtxt sig_msg sig_tyvars sig_theta sig_tau) $ - returnTc (Var (mkInstId over_lit), unitLIE over_lit, ty) + 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) -> + + checkSigTyVars sig_tyvars free_tvs `thenTc` \ zonked_sig_tyvars -> -tcExpr e (Lit lit@(LitLitLitIn s)) - = getSrcLocTc `thenNF_Tc` \ loc -> let - -- Get the callable class. Rather turgid and a HACK (ToDo). - ce = getE_CE e - cCallableClass = lookupCE ce (PreludeClass cCallableClassKey bottom) - bottom = panic "tcExpr:LitLitLit" + -- 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 - newPolyTyVarTy `thenNF_Tc` \ ty -> - - newDict (LitLitOrigin loc (_UNPK_ s)) cCallableClass ty `thenNF_Tc` \ dict -> - - returnTc (Lit (LitLitLit s ty), mkLIE [dict], ty) + returnTc ( generalised_arg, free_insts, + arg', sig_tau, lie_arg ) + where + sig_msg = ptext SLIT("When checking an expression type signature") \end{code} -Primitive literals: +%************************************************************************ +%* * +\subsection{The TAUT rules for variables} +%* * +%************************************************************************ \begin{code} -tcExpr e (Lit (CharPrimLit c)) - = returnTc (Lit (CharPrimLit c), nullLIE, charPrimTy) - -tcExpr e (Lit (StringPrimLit s)) - = returnTc (Lit (StringPrimLit s), nullLIE, addrPrimTy) +tcMonoExpr :: RenamedHsExpr -- Expession to type check + -> TcTauType -- Expected type (could be a type variable) + -> TcM (TcExpr, LIE) -tcExpr e (Lit (IntPrimLit i)) - = returnTc (Lit (IntPrimLit i), nullLIE, intPrimTy) +tcMonoExpr (HsVar name) res_ty + = tcId name `thenNF_Tc` \ (expr', lie, id_ty) -> + unifyTauTy res_ty id_ty `thenTc_` -tcExpr e (Lit (FloatPrimLit f)) - = returnTc (Lit (FloatPrimLit f), nullLIE, floatPrimTy) + -- 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 e (Lit (DoublePrimLit d)) - = returnTc (Lit (DoublePrimLit d), nullLIE, doublePrimTy) + returnTc (expr', lie) \end{code} -Unoverloaded literals: - \begin{code} -tcExpr e (Lit (CharLit c)) - = returnTc (Lit (CharLit c), nullLIE, charTy) - -tcExpr e (Lit (StringLit str)) - = returnTc (Lit (StringLit str), nullLIE, stringTy) +tcMonoExpr (HsIPVar name) res_ty + = newIPDict (IPOcc name) name res_ty `thenNF_Tc` \ ip -> + returnNF_Tc (HsIPVar (instToId ip), unitLIE ip) \end{code} %************************************************************************ @@ -167,49 +192,66 @@ tcExpr e (Lit (StringLit str)) %************************************************************************ \begin{code} -tcExpr e (Lam match) - = tcMatch e match `thenTc` \ (match',lie,ty) -> - returnTc (Lam match',lie,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 e (App e1 e2) = accum e1 [e2] - where - accum (App e1 e2) args = accum e1 (e2:args) - accum fun args = tcApp (foldl App) e fun args +tcMonoExpr (NegApp expr) res_ty + = tcLookupSyntaxName negateName `thenNF_Tc` \ neg -> + tcMonoExpr (HsApp (HsVar neg) expr) res_ty + +tcMonoExpr (HsLam match) res_ty + = tcMatchLambda match res_ty `thenTc` \ (match',lie) -> + returnTc (HsLam match', lie) + +tcMonoExpr (HsApp e1 e2) res_ty = accum e1 [e2] + where + accum (HsApp e1 e2) args = accum e1 (e2:args) + accum fun args + = tcApp fun args res_ty `thenTc` \ (fun', args', lie) -> + returnTc (foldl HsApp fun' args', lie) -- equivalent to (op e1) e2: -tcExpr e (OpApp e1 op e2) - = tcApp (\fun [arg1,arg2] -> OpApp arg1 fun arg2) e op [e1,e2] +tcMonoExpr (OpApp arg1 op fix arg2) res_ty + = tcApp op [arg1,arg2] res_ty `thenTc` \ (op', [arg1', arg2'], lie) -> + returnTc (OpApp arg1' op' fix arg2', lie) \end{code} Note that the operators in sections are expected to be binary, and a type error will occur if they aren't. \begin{code} --- equivalent to --- \ x -> e op x, +-- Left sections, equivalent to +-- \ x -> e op x, -- or --- \ x -> op e x, +-- \ x -> op e x, -- or just -- op e -tcExpr e (SectionL expr op) - = tcApp (\ fun [arg] -> SectionL arg fun) e op [expr] +tcMonoExpr in_expr@(SectionL arg op) res_ty + = tcApp op [arg] res_ty `thenTc` \ (op', [arg'], lie) -> --- equivalent to \ x -> x op expr, or --- \ x -> op x expr + -- Check that res_ty is a function type + -- Without this check we barf in the desugarer on + -- f op = (3 `op`) + -- because it tries to desugar to + -- f op = \r -> 3 op r + -- so (3 `op`) had better be a function! + tcAddErrCtxt (sectionLAppCtxt in_expr) $ + unifyFunTy res_ty `thenTc_` -tcExpr e (SectionR op expr) - = tcExpr e op `thenTc` \ (op', lie1, op_ty) -> - tcExpr e expr `thenTc` \ (expr',lie2, expr_ty) -> - newOpenTyVarTy `thenNF_Tc` \ ty1 -> - newOpenTyVarTy `thenNF_Tc` \ ty2 -> - let - result_ty = mkFunTy ty1 ty2 - in - unifyTauTy op_ty (mkFunTy ty1 (mkFunTy expr_ty ty2)) - (SectionRAppCtxt op expr) `thenTc_` + returnTc (SectionL arg' op', lie) + +-- Right sections, equivalent to \ x -> x op expr, or +-- \ x -> op x expr - returnTc (SectionR op' expr', plusLIE lie1 lie2, result_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) -> + tcMonoExpr expr arg2_ty `thenTc` \ (expr',lie2) -> + unifyTauTy res_ty (mkFunTy arg1_ty op_res_ty) `thenTc_` + returnTc (SectionR op' expr', lie1 `plusLIE` lie2) \end{code} The interesting thing about @ccall@ is that it is just a template @@ -220,478 +262,754 @@ arg/result types); unify them with the args/result; and store them for later use. \begin{code} -tcExpr e (CCall lbl args may_gc is_asm ignored_fake_result_ty) - = getSrcLocTc `thenNF_Tc` \ src_loc -> +tcMonoExpr (HsCCall lbl args may_gc is_asm ignored_fake_result_ty) res_ty + = -- Get the callable and returnable classes. + tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass -> + tcLookupClass cReturnableClassName `thenNF_Tc` \ cReturnableClass -> + tcLookupTyCon ioTyConName `thenNF_Tc` \ ioTyCon -> let - -- Get the callable and returnable classes. Rather turgid (ToDo). - ce = getE_CE e - cCallableClass = lookupCE ce (PreludeClass cCallableClassKey bottom) - cReturnableClass = lookupCE ce (PreludeClass cReturnableClassKey bottom) - bottom = panic "tcExpr:CCall" + new_arg_dict (arg, arg_ty) + = newDicts (CCallOrigin (_UNPK_ lbl) (Just arg)) + [mkClassPred cCallableClass [arg_ty]] `thenNF_Tc` \ arg_dicts -> + returnNF_Tc arg_dicts -- Actually a singleton bag - new_arg_dict (arg, arg_ty) = newDict (CCallOrigin src_loc (_UNPK_ lbl) (Just arg)) - cCallableClass arg_ty - - result_origin = CCallOrigin src_loc (_UNPK_ lbl) Nothing {- Not an arg -} + result_origin = CCallOrigin (_UNPK_ lbl) Nothing {- Not an arg -} in - + -- Arguments - tcExprs e args `thenTc` \ (args', args_lie, arg_tys) -> + 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 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. - newPolyTyVarTy `thenNF_Tc` \ result_ty -> + newTyVarTy liftedTypeKind `thenNF_Tc` \ result_ty -> + let + io_result_ty = mkTyConApp ioTyCon [result_ty] + in + unifyTauTy res_ty io_result_ty `thenTc_` -- Construct the extra insts, which encode the -- constraints on the argument and result types. - mapNF_Tc new_arg_dict (args `zip` arg_tys) `thenNF_Tc` \ arg_dicts -> - newDict result_origin cReturnableClass result_ty `thenNF_Tc` \ res_dict -> - - returnTc (CCall lbl args' may_gc is_asm result_ty, - args_lie `plusLIE` mkLIE (res_dict : arg_dicts), - mkPrimIoTy result_ty) + mapNF_Tc new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s -> + newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenNF_Tc` \ ccres_dict -> + returnTc (HsCCall lbl args' may_gc is_asm io_result_ty, + mkLIE (ccres_dict ++ concat ccarg_dicts_s) `plusLIE` args_lie) \end{code} \begin{code} -tcExpr e (SCC label expr) - = tcExpr e expr `thenTc` \ (expr', lie, expr_ty) -> - -- No unification. Give SCC the type of expr - returnTc (SCC label expr', lie, expr_ty) +tcMonoExpr (HsSCC lbl expr) res_ty + = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) -> + returnTc (HsSCC lbl expr', lie) + +tcMonoExpr (HsLet binds expr) res_ty + = tcBindsAndThen + combiner + binds -- Bindings to check + tc_expr `thenTc` \ (expr', lie) -> + returnTc (expr', lie) + where + tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) -> + returnTc (expr', lie) + combiner is_rec bind expr = HsLet (mkMonoBind bind [] is_rec) expr + +tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty + = tcAddSrcLoc src_loc $ + tcAddErrCtxt (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 + -- + -- Not only that, but it's better to check the matches on their + -- own, so that we get the expected results for scoped type variables. + -- f x = case x of + -- (p::a, q::b) -> (q,p) + -- The above should work: the match (p,q) -> (q,p) is polymorphic as + -- claimed by the pattern signatures. But if we typechecked the + -- match with x in scope and x's type as the expected type, we'd be hosed. + + tcMatchesCase matches res_ty `thenTc` \ (scrut_ty, matches', lie2) -> + + tcAddErrCtxt (caseScrutCtxt scrut) ( + tcMonoExpr scrut scrut_ty + ) `thenTc` \ (scrut',lie1) -> + + returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2) + +tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty + = tcAddSrcLoc src_loc $ + tcAddErrCtxt (predCtxt pred) ( + tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) -> + + tcMonoExpr b1 res_ty `thenTc` \ (b1',lie2) -> + tcMonoExpr b2 res_ty `thenTc` \ (b2',lie3) -> + returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3)) +\end{code} -tcExpr e (Let binds expr) - = tcLocalBindsAndThen e - Let -- The combiner - binds -- Bindings to check - (\ e -> tcExpr e expr) -- Typechecker for the expression +\begin{code} +tcMonoExpr expr@(HsDo do_or_lc stmts src_loc) res_ty + = tcDoStmts do_or_lc stmts src_loc res_ty +\end{code} + +\begin{code} +tcMonoExpr in_expr@(ExplicitList exprs) res_ty -- Non-empty list + = unifyListTy res_ty `thenTc` \ elt_ty -> + mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) -> + returnTc (ExplicitListOut elt_ty exprs', plusLIEs lies) + where + tc_elt elt_ty expr + = tcAddErrCtxt (listCtxt expr) $ + tcMonoExpr expr elt_ty + +tcMonoExpr (ExplicitTuple exprs boxity) res_ty + = unifyTupleTy boxity (length exprs) res_ty `thenTc` \ arg_tys -> + mapAndUnzipTc (\ (expr, arg_ty) -> tcMonoExpr expr arg_ty) + (exprs `zip` arg_tys) -- we know they're of equal length. + `thenTc` \ (exprs', lies) -> + returnTc (ExplicitTuple exprs' boxity, plusLIEs lies) + +tcMonoExpr expr@(RecordCon con_name rbinds) res_ty + = tcAddErrCtxt (recordConCtxt expr) $ + tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) -> + let + (_, record_ty) = splitFunTys con_tau + (tycon, ty_args, _) = splitAlgTyConApp record_ty + in + 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 data_con + in + if not (null bad_fields) then + mapNF_Tc (addErrTc . badFieldCon con_name) bad_fields `thenNF_Tc_` + failTc -- Fail now, because tcRecordBinds will crash on a bad field + else + + -- Typecheck the record bindings + tcRecordBinds tycon ty_args rbinds `thenTc` \ (rbinds', rbinds_lie) -> + + let + (missing_s_fields, missing_fields) = missingFields rbinds data_con + in + checkTcM (null missing_s_fields) + (mapNF_Tc (addErrTc . missingStrictFieldCon con_name) missing_s_fields `thenNF_Tc_` + returnNF_Tc ()) `thenNF_Tc_` + doptsTc Opt_WarnMissingFields `thenNF_Tc` \ warn -> + checkTcM (not (warn && not (null missing_fields))) + (mapNF_Tc ((warnTc True) . missingFieldCon con_name) missing_fields `thenNF_Tc_` + returnNF_Tc ()) `thenNF_Tc_` + + 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: +-- +-- 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. + +tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty + = tcAddErrCtxt (recordUpdCtxt expr) $ + + -- STEP 0 + -- Check that the field names are really field names + ASSERT( not (null rbinds) ) + let + field_names = [field_name | (field_name, _, _) <- rbinds] + in + mapNF_Tc tcLookupGlobal_maybe field_names `thenNF_Tc` \ maybe_sel_ids -> + let + bad_guys = [ addErrTc (notSelector field_name) + | (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids, + case maybe_sel_id of + Just (AnId sel_id) -> not (isRecordSelector sel_id) + other -> True + ] + 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, _, _, _, _, _) = dataConSig (head data_cons) + in + tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) -> + + -- STEP 2 + -- Check that at least one constructor has all the named fields + -- i.e. has an empty set of bad fields returned by badFields + checkTc (any (null . badFields rbinds) data_cons) + (badFieldsUpd rbinds) `thenTc_` + + -- 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 + unifyTauTy res_ty result_record_ty `thenTc_` + tcRecordBinds tycon result_inst_tys rbinds `thenTc` \ (rbinds', rbinds_lie) -> + + -- 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 = [recordSelectorFieldLabel sel_id | (sel_id, _, _) <- rbinds'] + con_field_lbls_s = map dataConFieldLabels data_cons -tcExpr e (Case expr matches) - = tcExpr e expr `thenTc` \ (expr',lie1,expr_ty) -> - tcMatchesCase e matches `thenTc` \ (matches',lie2,match_ty) -> - newOpenTyVarTy `thenNF_Tc` \ result_ty -> + -- 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 - unifyTauTy (mkFunTy expr_ty result_ty) match_ty - (CaseCtxt expr matches) `thenTc_` + non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls + common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls) - returnTc (Case expr' matches', plusLIE lie1 lie2, result_ty) + mk_inst_ty (tyvar, result_inst_ty) + | tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type + | otherwise = newTyVarTy liftedTypeKind -- Fresh type + in + mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys -> -tcExpr e (If pred b1 b2) - = tcExpr e pred `thenTc` \ (pred',lie1,predTy) -> + -- STEP 5 + -- Typecheck the expression to be updated + let + record_ty = mkTyConApp tycon inst_tys + in + tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) -> + + -- STEP 6 + -- Figure out the LIE we need. We have to generate some + -- dictionaries for the data type context, since we are going to + -- do some construction. + -- + -- 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. + let + (tyvars, theta, _, _, _, _) = dataConSig (head data_cons) + inst_env = mkTopTyVarSubst tyvars result_inst_tys + theta' = substTheta inst_env theta + in + newDicts RecordUpdOrigin theta' `thenNF_Tc` \ dicts -> + + -- Phew! + returnTc (RecordUpdOut record_expr' result_record_ty (map instToId dicts) rbinds', + mkLIE dicts `plusLIE` record_lie `plusLIE` rbinds_lie) + +tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty + = unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) -> + + tcLookupGlobalId enumFromName `thenNF_Tc` \ sel_id -> + newMethod (ArithSeqOrigin seq) + sel_id [elt_ty] `thenNF_Tc` \ enum_from -> + + returnTc (ArithSeqOut (HsVar (instToId enum_from)) (From expr'), + lie1 `plusLIE` unitLIE enum_from) + +tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty + = tcAddErrCtxt (arithSeqCtxt in_expr) $ + unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> + tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> + tcLookupGlobalId enumFromThenName `thenNF_Tc` \ sel_id -> + newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_then -> + + returnTc (ArithSeqOut (HsVar (instToId enum_from_then)) + (FromThen expr1' expr2'), + lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_then) + +tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty + = tcAddErrCtxt (arithSeqCtxt in_expr) $ + unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> + tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> + tcLookupGlobalId enumFromToName `thenNF_Tc` \ sel_id -> + newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_to -> + + returnTc (ArithSeqOut (HsVar (instToId enum_from_to)) + (FromTo expr1' expr2'), + lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_to) + +tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty + = tcAddErrCtxt (arithSeqCtxt in_expr) $ + unifyListTy res_ty `thenTc` \ elt_ty -> + tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) -> + tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) -> + tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) -> + tcLookupGlobalId enumFromThenToName `thenNF_Tc` \ sel_id -> + newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ eft -> + + returnTc (ArithSeqOut (HsVar (instToId eft)) + (FromThenTo expr1' expr2' expr3'), + lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft) +\end{code} - unifyTauTy predTy boolTy (PredCtxt pred) `thenTc_` +%************************************************************************ +%* * +\subsection{Expressions type signatures} +%* * +%************************************************************************ - tcExpr e b1 `thenTc` \ (b1',lie2,result_ty) -> - tcExpr e b2 `thenTc` \ (b2',lie3,b2Ty) -> +\begin{code} +tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty + = tcSetErrCtxt (exprSigCtxt in_expr) $ + tcHsSigType poly_ty `thenTc` \ sig_tc_ty -> + + if not (isSigmaTy sig_tc_ty) then + -- Easy case + unifyTauTy sig_tc_ty res_ty `thenTc_` + tcMonoExpr expr sig_tc_ty + + else -- Signature is polymorphic + tcPolyExpr expr sig_tc_ty `thenTc` \ (_, _, expr, expr_ty, lie) -> + + -- Now match the signature type with res_ty. + -- We must not do this earlier, because res_ty might well + -- mention variables free in the environment, and we'd get + -- bogus complaints about not being able to for-all the + -- sig_tyvars + unifyTauTy res_ty expr_ty `thenTc_` + + -- If everything is ok, return the stuff unchanged, except for + -- the effect of any substutions etc. We simply discard the + -- result of the tcSimplifyCheck (inside tcPolyExpr), except for any default + -- resolution it may have done, which is recorded in the + -- substitution. + returnTc (expr, lie) +\end{code} - unifyTauTy result_ty b2Ty (BranchCtxt b1 b2) `thenTc_` +Implicit Parameter bindings. - returnTc (If pred' b1' b2', plusLIE lie1 (plusLIE lie2 lie3), result_ty) +\begin{code} +tcMonoExpr (HsWith expr binds) res_ty + = tcMonoExpr expr res_ty `thenTc` \ (expr', expr_lie) -> + mapAndUnzipTc tcIPBind binds `thenTc` \ (pairs, bind_lies) -> -tcExpr e (ListComp expr quals) - = mkIdsWithPolyTyVarTys binders `thenNF_Tc` \ lve -> - -- Binders of a list comprehension must be boxed. + -- If the binding binds ?x = E, we must now + -- discharge any ?x constraints in expr_lie + tcSimplifyIPs (map fst pairs) expr_lie `thenTc` \ (expr_lie', dict_binds) -> let - new_e = growE_LVE e lve + binds' = [(instToId ip, rhs) | (ip,rhs) <- pairs] + expr'' = HsLet (mkMonoBind dict_binds [] Recursive) expr' in - tcQuals new_e quals `thenTc` \ (quals',lie1) -> - tcExpr new_e expr `thenTc` \ (expr', lie2, ty) -> - returnTc (ListComp expr' quals', plusLIE lie1 lie2, mkListTy ty) - where - binders = collectQualBinders quals + 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} +%************************************************************************ +%* * +\subsection{@tcApp@ typchecks an application} +%* * +%************************************************************************ + \begin{code} -tcExpr e (ExplicitList []) - = newPolyTyVarTy `thenNF_Tc` \ tyvar_ty -> - returnTc (ExplicitListOut tyvar_ty [], nullLIE, mkListTy tyvar_ty) +tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args + -> TcType -- Expected result type of application + -> TcM (TcExpr, [TcExpr], -- Translated fun and args + LIE) -tcExpr e (ExplicitList exprs) -- Non-empty list - = tcExprs e exprs `thenTc` \ (exprs', lie, tys@(elt_ty:_)) -> - unifyTauTyList tys (ListCtxt exprs) `thenTc_` - returnTc (ExplicitListOut elt_ty exprs', lie, mkListTy elt_ty) +tcApp fun args res_ty + = -- First type-check the function + tcExpr_id fun `thenTc` \ (fun', lie_fun, fun_ty) -> -tcExpr e (ExplicitTuple exprs) - = tcExprs e exprs `thenTc` \ (exprs', lie, tys) -> - returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys) + tcAddErrCtxt (wrongArgsCtxt "too many" fun args) ( + split_fun_ty fun_ty (length args) + ) `thenTc` \ (expected_arg_tys, actual_result_ty) -> -tcExpr e (ArithSeqIn seq@(From expr)) - = getSrcLocTc `thenNF_Tc` \ loc -> - tcExpr e expr `thenTc` \ (expr', lie, ty) -> - let - enum_from_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFrom") - in - newMethod (ArithSeqOrigin seq loc) - enum_from_id [ty] `thenNF_Tc` \ enum_from -> + -- Unify with expected result before type-checking the args + -- This is when we might detect a too-few args situation + tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) ( + unifyTauTy res_ty actual_result_ty + ) `thenTc_` + + -- Now typecheck the args + mapAndUnzipTc (tcArg fun) + (zip3 args expected_arg_tys [1..]) `thenTc` \ (args', lie_args_s) -> + + -- Check that the result type doesn't have any nested for-alls. + -- For example, a "build" on its own is no good; it must be applied to something. + checkTc (isTauTy actual_result_ty) + (lurkingRank2Err fun actual_result_ty) `thenTc_` - returnTc (ArithSeqOut (Var (mkInstId enum_from)) (From expr'), - plusLIE (unitLIE enum_from) lie, - mkListTy ty) + returnTc (fun', args', lie_fun `plusLIE` plusLIEs lie_args_s) -tcExpr e (ArithSeqIn seq@(FromThen expr1 expr2)) - = getSrcLocTc `thenNF_Tc` \ loc -> - tcExpr e expr1 `thenTc` \ (expr1',lie1,ty1) -> - tcExpr e expr2 `thenTc` \ (expr2',lie2,ty2) -> - unifyTauTyList [ty1, ty2] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_` +-- If an error happens we try to figure out whether the +-- function has been given too many or too few arguments, +-- and say so +checkArgsCtxt fun args expected_res_ty actual_res_ty tidy_env + = zonkTcType expected_res_ty `thenNF_Tc` \ exp_ty' -> + zonkTcType actual_res_ty `thenNF_Tc` \ act_ty' -> let - enum_from_then_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromThen") + (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 - newMethod (ArithSeqOrigin seq loc) - enum_from_then_id [ty1] `thenNF_Tc` \ enum_from_then -> + returnNF_Tc (env2, message) - returnTc (ArithSeqOut (Var (mkInstId enum_from_then)) - (FromThen expr1' expr2'), - (unitLIE enum_from_then) `plusLIE` lie1 `plusLIE` lie2, - mkListTy ty1) -tcExpr e (ArithSeqIn seq@(FromTo expr1 expr2)) - = getSrcLocTc `thenNF_Tc` \ loc -> - tcExpr e expr1 `thenTc` \ (expr1',lie1,ty1) -> - tcExpr e expr2 `thenTc` \ (expr2',lie2,ty2) -> +split_fun_ty :: TcType -- The type of the function + -> Int -- Number of arguments + -> TcM ([TcType], -- Function argument types + TcType) -- Function result types - unifyTauTyList [ty1,ty2] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_` - let - enum_from_to_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromTo") - in - newMethod (ArithSeqOrigin seq loc) - enum_from_to_id [ty1] `thenNF_Tc` \ enum_from_to -> - returnTc (ArithSeqOut (Var (mkInstId enum_from_to)) - (FromTo expr1' expr2'), - (unitLIE enum_from_to) `plusLIE` lie1 `plusLIE` lie2, - mkListTy ty1) - -tcExpr e (ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) - = getSrcLocTc `thenNF_Tc` \ loc -> - tcExpr e expr1 `thenTc` \ (expr1',lie1,ty1) -> - tcExpr e expr2 `thenTc` \ (expr2',lie2,ty2) -> - tcExpr e expr3 `thenTc` \ (expr3',lie3,ty3) -> - - unifyTauTyList [ty1,ty2,ty3] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_` - let - enum_from_then_to_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromThenTo") - in - newMethod (ArithSeqOrigin seq loc) - enum_from_then_to_id [ty1] `thenNF_Tc` \ enum_from_then_to -> +split_fun_ty fun_ty 0 + = returnTc ([], fun_ty) - returnTc (ArithSeqOut (Var (mkInstId enum_from_then_to)) - (FromThenTo expr1' expr2' expr3'), - (unitLIE enum_from_then_to) `plusLIE` lie1 `plusLIE` lie2 `plusLIE` lie3, - mkListTy ty1) +split_fun_ty fun_ty n + = -- Expect the function to have type A->B + unifyFunTy fun_ty `thenTc` \ (arg_ty, res_ty) -> + split_fun_ty res_ty (n-1) `thenTc` \ (arg_tys, final_res_ty) -> + returnTc (arg_ty:arg_tys, final_res_ty) \end{code} -%************************************************************************ -%* * -\subsection{Expressions type signatures} -%* * -%************************************************************************ - \begin{code} -tcExpr e (ExprWithTySig expr poly_ty) - = tcExpr e expr `thenTc` \ (texpr, lie, tau_ty) -> - babyTcMtoTcM (tcPolyType (getE_CE e) (getE_TCE e) nullTVE poly_ty) `thenTc` \ sigma_sig -> - - -- Check the tau-type part - specTy SignatureOrigin sigma_sig `thenNF_Tc` \ (sig_tyvars, sig_dicts, sig_tau) -> - unifyTauTy tau_ty sig_tau (ExprSigCtxt expr sig_tau) `thenTc_` - - -- Check the type variables of the signature - applyTcSubstAndCollectTyVars (tvOfE e) `thenNF_Tc` \ env_tyvars -> - checkSigTyVars env_tyvars sig_tyvars sig_tau tau_ty (ExprSigCtxt expr sig_tau) - `thenTc` \ sig_tyvars' -> - - -- Check overloading constraints - tcSimplifyAndCheck - False {- Not top level -} - env_tyvars sig_tyvars' - sig_dicts (unMkLIE lie) - (ExprSigCtxt expr sigma_sig) `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) +tcArg :: RenamedHsExpr -- The function (for error messages) + -> (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) $ + tcExpr arg expected_arg_ty \end{code} + %************************************************************************ %* * -\subsection{Data Parallel Expressions (DPH only)} +\subsection{@tcId@ typchecks an identifier occurrence} %* * %************************************************************************ -Constraints enforced by the Static semantics for ParallelZF -$exp_1$ = << $exp_2$ | quals >> +\begin{code} +tcId :: Name -> NF_TcM (TcExpr, LIE, TcType) +tcId name -- Look up the Id and instantiate its type + = tcLookupId name `thenNF_Tc` \ id -> + tcInstId id +\end{code} -\begin{enumerate} -\item The type of the expression $exp_1$ is <<$exp_2$>> -\item The type of $exp_2$ must be in the class {\tt Processor} -\end{enumerate} +Typecheck expression which in most cases will be an Id. \begin{code} -#ifdef DPH -tcExpr e (ParallelZF expr quals) - = let binders = collectParQualBinders quals in - mkIdsWithPolyTyVarTys binders `thenNF_Tc` (\ lve -> - let e' = growE_LVE e lve in - tcParQuals e' quals `thenTc` (\ (quals',lie1) -> - tcExpr e' expr `thenTc` (\ (expr', lie2,ty) -> - getSrcLocTc `thenNF_Tc` (\ src_loc -> - if (isProcessorTy ty) then - returnTc (ParallelZF expr' quals', - plusLIE lie1 lie2 , - mkPodTy ty) - else - failTc (podCompLhsError ty src_loc) - )))) -#endif {- Data Parallel Haskell -} +tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, LIE, TcType) +tcExpr_id (HsVar name) = tcId name +tcExpr_id expr = newTyVarTy openTypeKind `thenNF_Tc` \ id_ty -> + tcMonoExpr expr id_ty `thenTc` \ (expr', lie_id) -> + returnTc (expr', lie_id, id_ty) \end{code} -Constraints enforced by the Static semantics for Explicit Pods -exp = << $exp_1$ ... $exp_n$>> (where $n >= 0$) -\begin{enumerate} -\item The type of the all the expressions in the Pod must be the same. -\item The type of an expression in a POD must be in class {\tt Processor} -\end{enumerate} +%************************************************************************ +%* * +\subsection{@tcDoStmts@ typechecks a {\em list} of do statements} +%* * +%************************************************************************ \begin{code} -#ifdef DPH -tcExpr e (ExplicitPodIn exprs) - = panic "Ignoring explicit PODs for the time being" -{- - = tcExprs e exprs `thenTc` (\ (exprs',lie,tys) -> - newPolyTyVarTy `thenNF_Tc` (\ elt_ty -> - newDict processorClass elt_ty `thenNF_Tc` (\ procDict -> - let - procLie = mkLIEFromDicts procDict - in - unifyTauTyList (elt_ty:tys) (PodCtxt exprs) `thenTc_` - - returnTc ((App - (DictApp - (TyApp (Var toPodId) [elt_ty]) - procDict) - (ExplicitListOut elt_ty exprs')), - plusLIE procLie lie, - mkPodTy elt_ty) - ))) -} -#endif {- Data Parallel Haskell -} +tcDoStmts do_or_lc stmts src_loc res_ty + = -- get the Monad and MonadZero classes + -- create type consisting of a fresh monad tyvar + ASSERT( not (null stmts) ) + tcAddSrcLoc src_loc $ + + -- If it's a comprehension we're dealing with, + -- force it to be a list comprehension. + -- (as of Haskell 98, monad comprehensions are no more.) + (case do_or_lc of + ListComp -> unifyListTy res_ty `thenTc` \ elt_ty -> + returnNF_Tc (mkTyConTy listTyCon, (mkListTy, elt_ty)) + + _ -> newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenNF_Tc` \ m_ty -> + newTyVarTy liftedTypeKind `thenNF_Tc` \ elt_ty -> + unifyTauTy res_ty (mkAppTy m_ty elt_ty) `thenTc_` + returnNF_Tc (m_ty, (mkAppTy m_ty, elt_ty)) + ) `thenNF_Tc` \ (tc_ty, m_ty) -> + + tcStmts do_or_lc m_ty stmts `thenTc` \ (stmts', stmts_lie) -> + + -- Build the then and zero methods in case we need them + -- It's important that "then" and "return" appear just once in the final LIE, + -- not only for typechecker efficiency, but also because otherwise during + -- simplification we end up with silly stuff like + -- then = case d of (t,r) -> t + -- then = then + -- where the second "then" sees that it already exists in the "available" stuff. + -- + tcLookupGlobalId returnMName `thenNF_Tc` \ return_sel_id -> + tcLookupGlobalId thenMName `thenNF_Tc` \ then_sel_id -> + tcLookupGlobalId failMName `thenNF_Tc` \ fail_sel_id -> + newMethod DoOrigin return_sel_id [tc_ty] `thenNF_Tc` \ return_inst -> + newMethod DoOrigin then_sel_id [tc_ty] `thenNF_Tc` \ then_inst -> + newMethod DoOrigin fail_sel_id [tc_ty] `thenNF_Tc` \ fail_inst -> + let + monad_lie = mkLIE [return_inst, then_inst, fail_inst] + in + returnTc (HsDoOut do_or_lc stmts' + (instToId return_inst) (instToId then_inst) (instToId fail_inst) + res_ty src_loc, + stmts_lie `plusLIE` monad_lie) \end{code} -\begin{code} -#ifdef DPH -tcExpr e (ExplicitProcessor exprs expr) - = tcPidExprs e exprs `thenTc` (\ (exprs',lie1,tys) -> - tcExpr e expr `thenTc` (\ (expr',lie2,ty) -> - returnTc (ExplicitProcessor exprs' expr', - plusLIE lie1 lie2, - mkProcessorTy tys ty) - )) -#endif {- Data Parallel Haskell -} -\end{code} %************************************************************************ %* * -\subsection{@tcExprs@ typechecks a {\em list} of expressions} +\subsection{Record bindings} %* * %************************************************************************ -ToDo: Possibly find a version of a listTc TcM which would pass the -appropriate functions for the LIE. +Game plan for record bindings +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +1. Find the TyCon for the bindings, from the first field label. + +2. Instantiate its tyvars and unify (T a1 .. an) with expected_ty. + +For each binding field = value + +3. Instantiate the field type (from the field label) using the type + envt from step 2. + +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. + + \begin{code} -tcExprs :: E -> [RenamedExpr] -> TcM ([TypecheckedExpr],LIE,[TauType]) +tcRecordBinds + :: TyCon -- Type constructor for the record + -> [TcType] -- Args of this type constructor + -> RenamedRecordBinds + -> TcM (TcRecordBinds, LIE) + +tcRecordBinds tycon ty_args rbinds + = mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) -> + returnTc (rbinds', plusLIEs lies) + where + tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args -tcExprs e [] = returnTc ([], nullLIE, []) -tcExprs e (expr:exprs) - = tcExpr e expr `thenTc` \ (expr', lie1, ty) -> - tcExprs e exprs `thenTc` \ (exprs', lie2, tys) -> - returnTc (expr':exprs', plusLIE lie1 lie2, ty:tys) -\end{code} + 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 + + tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) -> + + returnTc ((sel_id, rhs', pun_flag), lie) + +badFields rbinds data_con + = [field_name | (field_name, _, _) <- rbinds, + not (field_name `elem` field_names) + ] + where + field_names = map fieldLabelName (dataConFieldLabels data_con) +missingFields rbinds data_con + | null field_labels = ([], []) -- Not declared as a record; + -- But C{} is still valid + | otherwise + = (missing_strict_fields, other_missing_fields) + where + missing_strict_fields + = [ fl | (fl, str) <- field_info, + isMarkedStrict str, + not (fieldLabelName fl `elem` field_names_used) + ] + other_missing_fields + = [ fl | (fl, str) <- field_info, + not (isMarkedStrict str), + not (fieldLabelName fl `elem` field_names_used) + ] + + field_names_used = [ field_name | (field_name, _, _) <- rbinds ] + field_labels = dataConFieldLabels data_con + + field_info = zipEqual "missingFields" + field_labels + (drop (length ex_theta) (dataConStrictMarks data_con)) + -- The 'drop' is because dataConStrictMarks + -- includes the existential dictionaries + (_, _, _, ex_theta, _, _) = dataConSig data_con +\end{code} %************************************************************************ %* * -\subsection{@tcApp@ typchecks an application} +\subsection{@tcMonoExprs@ typechecks a {\em list} of expressions} %* * %************************************************************************ \begin{code} -tcApp :: (TypecheckedExpr -> [TypecheckedExpr] -> TypecheckedExpr) -- Result builder - -> E - -> RenamedExpr - -> [RenamedExpr] - -> TcM (TypecheckedExpr, LIE, UniType) - -tcApp build_result_expression e orig_fun arg_exprs - = tcExpr' e orig_fun (length arg_exprs) - `thenTc` \ (fun', lie_fun, fun_ty) -> - unify_fun 1 fun' lie_fun arg_exprs fun_ty - where - -- Used only in the error message - maybe_fun_id = case orig_fun of - Var name -> Just (lookupE_Value e name) - other -> Nothing - - unify_args :: Int -- Current argument number - -> TypecheckedExpr -- Current rebuilt expression - -> LIE -- Corresponding LIE - -> [RenamedExpr] -- Remaining args - -> [TauType] -- Remaining arg types - -> TauType -- result type - -> TcM (TypecheckedExpr, LIE, UniType) - - unify_args arg_no fun lie (arg:args) (arg_ty:arg_tys) fun_res_ty - = tcExpr e arg `thenTc` \ (arg', lie_arg, actual_arg_ty) -> - - -- These applyTcSubstToTy's are just to improve the error message... - applyTcSubstToTy actual_arg_ty `thenNF_Tc` \ actual_arg_ty' -> - applyTcSubstToTy arg_ty `thenNF_Tc` \ arg_ty' -> - let - err_ctxt = FunAppCtxt orig_fun maybe_fun_id arg arg_ty' actual_arg_ty' arg_no - in - matchArgTy e arg_ty' arg' lie_arg actual_arg_ty' err_ctxt - `thenTc` \ (arg'', lie_arg') -> +tcMonoExprs :: [RenamedHsExpr] -> [TcType] -> TcM ([TcExpr], LIE) - unify_args (arg_no+1) (App fun arg'') (lie `plusLIE` lie_arg') args arg_tys fun_res_ty +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} - unify_args arg_no fun lie [] arg_tys fun_res_ty - = -- We've run out of actual arguments. Check that none of - -- arg_tys has a for-all at the top. For example, "build" on - -- its own is no good; it must be applied to something. - let - result_ty = glueTyArgs arg_tys fun_res_ty - in - getSrcLocTc `thenNF_Tc` \ loc -> - checkTc (not (isTauTy result_ty)) - (underAppliedTyErr result_ty loc) `thenTc_` - returnTc (fun, lie, result_ty) - -- When we run out of arg_tys we go back to unify_fun in the hope - -- that our unification work may have shown up some more arguments - unify_args arg_no fun lie args [] fun_res_ty - = unify_fun arg_no fun lie args fun_res_ty +%************************************************************************ +%* * +\subsection{Literals} +%* * +%************************************************************************ +Overloaded literals. - unify_fun :: Int -- Current argument number - -> TypecheckedExpr -- Current rebuilt expression - -> LIE -- Corresponding LIE - -> [RenamedExpr] -- Remaining args - -> TauType -- Remaining function type - -> TcM (TypecheckedExpr, LIE, UniType) +\begin{code} +tcLit :: HsLit -> TcType -> TcM (TcExpr, LIE) +tcLit (HsLitLit s _) res_ty + = tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass -> + newDicts (LitLitOrigin (_UNPK_ s)) + [mkClassPred cCallableClass [res_ty]] `thenNF_Tc` \ dicts -> + returnTc (HsLit (HsLitLit s res_ty), mkLIE dicts) + +tcLit lit res_ty + = unifyTauTy res_ty (simpleHsLitTy lit) `thenTc_` + returnTc (HsLit lit, emptyLIE) +\end{code} - unify_fun arg_no fun lie args fun_ty - = -- Find out as much as possible about the function - applyTcSubstToTy fun_ty `thenNF_Tc` \ fun_ty' -> - -- Now see whether it has any arguments - case (splitTyArgs fun_ty') of +%************************************************************************ +%* * +\subsection{Errors and contexts} +%* * +%************************************************************************ - ([], _) -> -- Function has no arguments left +Mini-utils: - newOpenTyVarTy `thenNF_Tc` \ result_ty -> - tcExprs e args `thenTc` \ (args', lie_args, arg_tys) -> +Boring and alphabetical: +\begin{code} +arithSeqCtxt expr + = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr) - -- At this point, a unification error must mean the function is - -- being applied to too many arguments. - unifyTauTy fun_ty' (glueTyArgs arg_tys result_ty) - (TooManyArgsCtxt orig_fun) `thenTc_` +caseCtxt expr + = hang (ptext SLIT("In the case expression:")) 4 (ppr expr) - returnTc (build_result_expression fun args', - lie `plusLIE` lie_args, - result_ty) +caseScrutCtxt expr + = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr) - (fun_arg_tys, fun_res_ty) -> -- Function has non-empty list of argument types +exprSigCtxt expr + = hang (ptext SLIT("In an expression with a type signature:")) + 4 (ppr expr) - unify_args arg_no fun lie args fun_arg_tys fun_res_ty -\end{code} +listCtxt expr + = hang (ptext SLIT("In the list element:")) 4 (ppr expr) -\begin{code} -matchArgTy :: E - -> UniType -- Expected argument type - -> TypecheckedExpr -- Type checked argument - -> LIE -- Actual argument LIE - -> UniType -- Actual argument type - -> UnifyErrContext - -> TcM (TypecheckedExpr, -- The incoming type checked arg, - -- possibly wrapped in a big lambda - LIE) -- Possibly reduced somewhat - -matchArgTy e expected_arg_ty arg_expr actual_arg_lie actual_arg_ty err_ctxt - | isForAllTy expected_arg_ty - = -- Ha! The argument type of the function is a for-all type, - -- An example of rank-2 polymorphism. - - -- This applyTcSubstToTy is just to improve the error message.. - - applyTcSubstToTy actual_arg_ty `thenNF_Tc` \ actual_arg_ty' -> - - -- Instantiate the argument type - -- ToDo: give this a real origin - specTy UnknownOrigin expected_arg_ty `thenNF_Tc` \ (arg_tyvars, arg_lie, arg_tau) -> - - if not (null arg_lie) then - -- Paranoia check - panic "Non-null overloading in tcApp" - else - -- Assert: arg_lie = [] +predCtxt expr + = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr) - unifyTauTy arg_tau actual_arg_ty' err_ctxt `thenTc_` +sectionRAppCtxt expr + = hang (ptext SLIT("In the right section:")) 4 (ppr expr) - -- 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. - applyTcSubstAndCollectTyVars - (tvOfE e `unionLists` - extractTyVarsFromTy expected_arg_ty) `thenNF_Tc` \ free_tyvars -> - checkSigTyVars free_tyvars arg_tyvars arg_tau actual_arg_ty rank2_err_ctxt - `thenTc` \ arg_tyvars' -> - - -- Check that there's no overloading involved - -- Even if there isn't, there may be some Insts which mention the arg_tyvars, - -- but which, on simplification, don't actually need a dictionary involving - -- the tyvar. So we have to do a proper simplification right here. - let insts = unMkLIE actual_arg_lie - in - applyTcSubstToInsts insts `thenNF_Tc` \ insts' -> +sectionLAppCtxt expr + = hang (ptext SLIT("In the left section:")) 4 (ppr expr) - tcSimplifyRank2 arg_tyvars' insts' rank2_err_ctxt `thenTc` \ (free_insts, inst_binds) -> +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)) - -- This Let 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 arg_tyvars' (Let (mk_binds inst_binds) arg_expr), mkLIE free_insts) +wrongArgsCtxt too_many_or_few fun args + = hang (ptext SLIT("Probable cause:") <+> quotes (ppr fun) + <+> ptext SLIT("is applied to") <+> text too_many_or_few + <+> ptext SLIT("arguments in the call")) + 4 (parens (ppr the_app)) + where + the_app = foldl HsApp fun args -- Used in error messages + +appCtxt fun args + = ptext SLIT("In the application") <+> quotes (ppr the_app) + where + the_app = foldl HsApp fun args -- Used in error messages - | otherwise - = -- The ordinary, non-rank-2 polymorphic case - unifyTauTy expected_arg_ty actual_arg_ty err_ctxt `thenTc_` - returnTc (arg_expr, actual_arg_lie) +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]) +badFieldsUpd rbinds + = hang (ptext SLIT("No constructor has all these fields:")) + 4 (pprQuotedList fields) where - rank2_err_ctxt = Rank2ArgCtxt arg_expr expected_arg_ty + fields = [field | (field, _, _) <- rbinds] - mk_binds [] = EmptyBinds - mk_binds ((inst,rhs):inst_binds) = (SingleBind (NonRecBind (VarMonoBind (mkInstId inst) rhs))) - `ThenBinds` - mk_binds inst_binds -\end{code} +recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr +recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr -This version only does not check for 2nd order if it is applied. +notSelector field + = hsep [quotes (ppr field), ptext SLIT("is not a record selector")] -\begin{code} -tcExpr' :: E -> RenamedExpr -> Int -> TcM (TypecheckedExpr,LIE,UniType) +missingStrictFieldCon :: Name -> FieldLabel -> SDoc +missingStrictFieldCon con field + = hsep [ptext SLIT("Constructor") <+> quotes (ppr con), + ptext SLIT("does not have the required strict field"), quotes (ppr field)] -tcExpr' e v@(Var name) n - | n > 0 = specId (lookupE_Value e name) `thenNF_Tc` \ (expr, lie, ty) -> - returnTc (expr, lie, ty) -tcExpr' e exp n = tcExpr e exp +missingFieldCon :: Name -> FieldLabel -> SDoc +missingFieldCon con field + = hsep [ptext SLIT("Field") <+> quotes (ppr field), + ptext SLIT("is not initialised")] \end{code}