X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcExpr.lhs;h=7e5f0337bf621a4ff4f3fc07558bd68de2cb447e;hb=c5a65b1704212e3f4354841ff480c660a3b51fb6;hp=15b67291bdaab4944394da158b4b624e430e7e34;hpb=10521d8418fd3a1cf32882718b5bd28992db36fd;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcExpr.lhs b/ghc/compiler/typecheck/TcExpr.lhs index 15b6729..cf94f27 100644 --- a/ghc/compiler/typecheck/TcExpr.lhs +++ b/ghc/compiler/typecheck/TcExpr.lhs @@ -1,165 +1,184 @@ % -% (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 ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where + #include "HsVersions.h" -module TcExpr ( - tcExpr -#ifdef DPH - , tcExprs +#ifdef GHCI /* Only if bootstrapped */ +import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket ) +import Id ( Id ) +import TcType ( isTauTy ) +import TcEnv ( checkWellStaged ) +import HsSyn ( nlHsApp ) +import qualified DsMeta #endif - ) where -import TcMonad -- typechecking monad machinery -import TcMonadFns ( newPolyTyVarTy, newOpenTyVarTy, - newDict, newMethod, newOverloadedLit, - applyTcSubstAndCollectTyVars, - mkIdsWithPolyTyVarTys +import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields, + HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar ) +import TcHsSyn ( hsLitType, mkHsDictApp, mkHsTyApp, (<$>) ) +import TcRnMonad +import TcUnify ( Expected(..), newHole, zapExpectedType, zapExpectedTo, tcSubExp, tcGen, + unifyFunTy, zapToListTy, zapToPArrTy, zapToTupleTy ) +import BasicTypes ( isMarkedStrict ) +import Inst ( InstOrigin(..), + newOverloadedLit, newMethodFromName, newIPDict, + newDicts, newMethodWithGivenTy, + instToId, tcInstCall, tcInstDataCon ) -import AbsSyn -- the stuff being typechecked - - -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 TcBinds ( tcBindsAndThen ) +import TcEnv ( tcLookup, tcLookupId, checkProcLevel, + tcLookupDataCon, tcLookupGlobalId ) -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 TcArrows ( tcProc ) +import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) ) +import TcHsType ( tcHsSigType, UserTypeCtxt(..) ) +import TcPat ( badFieldCon ) +import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, zonkTcType ) +import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv), + tcSplitFunTys, tcSplitTyConApp, mkTyVarTys, + isSigmaTy, mkFunTy, mkFunTys, + mkTyConApp, tyVarsOfTypes, isLinearPred, + tcSplitSigmaTy, tidyOpenType + ) +import Kind ( openTypeKind, liftedTypeKind, argTypeKind ) + +import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon ) +import Id ( idType, recordSelectorFieldLabel, isRecordSelector ) +import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId ) +import Name ( Name ) +import TyCon ( TyCon, tyConTyVars, tyConTheta, tyConDataCons ) +import Subst ( mkTopTyVarSubst, substTheta, substTy ) +import VarSet ( emptyVarSet, elemVarSet ) +import TysWiredIn ( boolTy ) +import PrelNames ( enumFromName, enumFromThenName, + enumFromToName, enumFromThenToName, + enumFromToPName, enumFromThenToPName + ) +import ListSetOps ( minusList ) +import CmdLineOpts +import HscTypes ( TyThing(..) ) +import SrcLoc ( Located(..), unLoc, getLoc ) import Util +import Outputable +import FastString -tcExpr :: E -> RenamedExpr -> TcM (TypecheckedExpr, LIE, UniType) +#ifdef DEBUG +import TyCon ( isAlgTyCon ) +#endif \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) -> +-- tcCheckSigma does type *checking*; it's passed the expected type of the result +tcCheckSigma :: LHsExpr Name -- Expession to type check + -> TcSigmaType -- Expected type (could be a polytpye) + -> TcM (LHsExpr TcId) -- Generalised expr with expected type + +tcCheckSigma expr expected_ty + = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_` + tc_expr' expr expected_ty + +tc_expr' expr sigma_ty + | isSigmaTy sigma_ty + = tcGen sigma_ty emptyVarSet ( + \ rho_ty -> tcCheckRho expr rho_ty + ) `thenM` \ (gen_fn, expr') -> + returnM (L (getLoc expr') (gen_fn <$> unLoc expr')) + +tc_expr' expr rho_ty -- Monomorphic case + = tcCheckRho expr rho_ty +\end{code} - -- Check that there's no lurking rank-2 polymorphism - -- isTauTy is over-paranoid, because we don't expect - -- any submerged polymorphism other than rank-2 polymorphism +Typecheck expression which in most cases will be an Id. +The expression can return a higher-ranked type, such as + (forall a. a->a) -> Int +so we must create a hole to pass in as the expected tyvar. - getSrcLocTc `thenNF_Tc` \ loc -> - checkTc (not (isTauTy ty)) (lurkingRank2Err name ty loc) `thenTc_` - - returnTc stuff +\begin{code} +tcCheckRho :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId) +tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty) + +tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType) +tcInferRho (L loc (HsVar name)) = addSrcSpan loc $ + do { (e,ty) <- tcId name; return (L loc e, ty)} +tcInferRho expr = newHole `thenM` \ hole -> + tcMonoExpr expr (Infer hole) `thenM` \ expr' -> + readMutVar hole `thenM` \ rho_ty -> + returnM (expr', rho_ty) \end{code} + + %************************************************************************ %* * -\subsection{Literals} +\subsection{The TAUT rules for variables}TcExpr %* * %************************************************************************ -Overloaded literals. - \begin{code} -tcExpr e (Lit lit@(IntLit i)) - = getSrcLocTc `thenNF_Tc` \ loc -> - newPolyTyVarTy `thenNF_Tc` \ ty -> - let - from_int = lookupE_ClassOpByKey e numClassKey SLIT("fromInt") - from_integer = lookupE_ClassOpByKey e numClassKey SLIT("fromInteger") - in - newOverloadedLit (LiteralOrigin lit loc) - (OverloadedIntegral i from_int from_integer) - ty - `thenNF_Tc` \ over_lit -> - - returnTc (Var (mkInstId over_lit), unitLIE over_lit, ty) - -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 -> - - returnTc (Var (mkInstId over_lit), unitLIE over_lit, ty) - -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" - in - newPolyTyVarTy `thenNF_Tc` \ ty -> - - newDict (LitLitOrigin loc (_UNPK_ s)) cCallableClass ty `thenNF_Tc` \ dict -> - - returnTc (Lit (LitLitLit s ty), mkLIE [dict], ty) +tcMonoExpr :: LHsExpr Name -- Expession to type check + -> Expected TcRhoType -- Expected type (could be a type variable) + -- Definitely no foralls at the top + -- Can be a 'hole'. + -> TcM (LHsExpr TcId) + +tcMonoExpr (L loc expr) res_ty + = addSrcSpan loc (do { expr' <- tc_expr expr res_ty + ; return (L loc expr') }) + +tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId) +tc_expr (HsVar name) res_ty + = tcId name `thenM` \ (expr', id_ty) -> + tcSubExp res_ty id_ty `thenM` \ co_fn -> + returnM (co_fn <$> expr') + +tc_expr (HsIPVar ip) res_ty + = -- Implicit parameters must have a *tau-type* not a + -- type scheme. We enforce this by creating a fresh + -- type variable as its type. (Because res_ty may not + -- be a tau-type.) + newTyVarTy argTypeKind `thenM` \ ip_ty -> + -- argTypeKind: it can't be an unboxed tuple + newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) -> + extendLIE inst `thenM_` + tcSubExp res_ty ip_ty `thenM` \ co_fn -> + returnM (co_fn <$> HsIPVar ip') \end{code} -Primitive literals: - -\begin{code} -tcExpr e (Lit (CharPrimLit c)) - = returnTc (Lit (CharPrimLit c), nullLIE, charPrimTy) - -tcExpr e (Lit (StringPrimLit s)) - = returnTc (Lit (StringPrimLit s), nullLIE, addrPrimTy) - -tcExpr e (Lit (IntPrimLit i)) - = returnTc (Lit (IntPrimLit i), nullLIE, intPrimTy) - -tcExpr e (Lit (FloatPrimLit f)) - = returnTc (Lit (FloatPrimLit f), nullLIE, floatPrimTy) - -tcExpr e (Lit (DoublePrimLit d)) - = returnTc (Lit (DoublePrimLit d), nullLIE, doublePrimTy) -\end{code} -Unoverloaded literals: +%************************************************************************ +%* * +\subsection{Expressions type signatures} +%* * +%************************************************************************ \begin{code} -tcExpr e (Lit (CharLit c)) - = returnTc (Lit (CharLit c), nullLIE, charTy) - -tcExpr e (Lit (StringLit str)) - = returnTc (Lit (StringLit str), nullLIE, stringTy) +tc_expr in_expr@(ExprWithTySig expr poly_ty) res_ty + = addErrCtxt (exprCtxt in_expr) $ + tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty -> + tcThingWithSig sig_tc_ty (tcCheckRho expr) res_ty `thenM` \ (co_fn, expr') -> + returnM (co_fn <$> unLoc expr') + -- ToDo: nasty unLoc + +tc_expr (HsType ty) res_ty + = failWithTc (text "Can't handle type argument:" <+> ppr ty) + -- This is the syntax for type applications that I was planning + -- but there are difficulties (e.g. what order for type args) + -- so it's not enabled yet. + -- Can't eliminate it altogether from the parser, because the + -- same parser parses *patterns*. \end{code} + %************************************************************************ %* * \subsection{Other expression forms} @@ -167,531 +186,873 @@ tcExpr e (Lit (StringLit str)) %************************************************************************ \begin{code} -tcExpr e (Lam match) - = tcMatch e match `thenTc` \ (match',lie,ty) -> - returnTc (Lam match',lie,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 - --- equivalent to (op e1) e2: -tcExpr e (OpApp e1 op e2) - = tcApp (\fun [arg1,arg2] -> OpApp arg1 fun arg2) e op [e1,e2] +tc_expr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> + returnM (HsPar expr') +tc_expr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> + returnM (HsSCC lbl expr') +tc_expr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation + returnM (HsCoreAnn lbl expr') + +tc_expr (HsLit lit) res_ty = tcLit lit res_ty + +tc_expr (HsOverLit lit) res_ty + = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' -> + newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr -> + returnM (unLoc lit_expr) -- ToDo: nasty unLoc + +tc_expr (NegApp expr neg_name) res_ty + = tc_expr (HsApp (nlHsVar neg_name) expr) res_ty + -- ToDo: use tcSyntaxName + +tc_expr (HsLam match) res_ty + = tcMatchLambda match res_ty `thenM` \ match' -> + returnM (HsLam match') + +tc_expr (HsApp e1 e2) res_ty + = tcApp e1 [e2] res_ty \end{code} Note that the operators in sections are expected to be binary, and 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] +tc_expr in_expr@(SectionL arg1 op) res_ty + = tcInferRho op `thenM` \ (op', op_ty) -> + split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> + tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' -> + addErrCtxt (exprCtxt in_expr) $ + tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenM` \ co_fn -> + returnM (co_fn <$> SectionL arg1' op') --- equivalent to \ x -> x op expr, or +-- Right sections, equivalent to \ x -> x op expr, or -- \ x -> op x expr -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 (SectionR op' expr', plusLIE lie1 lie2, result_ty) -\end{code} - -The interesting thing about @ccall@ is that it is just a template -which we instantiate by filling in details about the types of its -argument and result (ie minimal typechecking is performed). So, the -basic story is that we allocate a load of type variables (to hold the -arg/result types); unify them with the args/result; and store them for -later use. +tc_expr in_expr@(SectionR op arg2) res_ty + = tcInferRho op `thenM` \ (op', op_ty) -> + split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> + tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' -> + addErrCtxt (exprCtxt in_expr) $ + tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn -> + returnM (co_fn <$> SectionR op' arg2') -\begin{code} -tcExpr e (CCall lbl args may_gc is_asm ignored_fake_result_ty) - = getSrcLocTc `thenNF_Tc` \ src_loc -> - 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) = newDict (CCallOrigin src_loc (_UNPK_ lbl) (Just arg)) - cCallableClass arg_ty +-- equivalent to (op e1) e2: - result_origin = CCallOrigin src_loc (_UNPK_ lbl) Nothing {- Not an arg -} - in - - -- Arguments - tcExprs e args `thenTc` \ (args', args_lie, arg_tys) -> - - -- The argument types can be unboxed or boxed; the result - -- type must, however, be boxed since it's an argument to the PrimIO - -- type constructor. - newPolyTyVarTy `thenNF_Tc` \ result_ty -> - - -- 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) +tc_expr in_expr@(OpApp arg1 op fix arg2) res_ty + = tcInferRho op `thenM` \ (op', op_ty) -> + split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) -> + tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' -> + tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' -> + addErrCtxt (exprCtxt in_expr) $ + tcSubExp res_ty op_res_ty `thenM` \ co_fn -> + returnM (OpApp arg1' op' fix arg2') \end{code} \begin{code} -tcExpr 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) - -tcExpr e (Let binds expr) - = tcLocalBindsAndThen e - Let -- The combiner - binds -- Bindings to check - (\ e -> tcExpr e expr) -- Typechecker for the expression - -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 -> - - unifyTauTy (mkFunTy expr_ty result_ty) match_ty - (CaseCtxt expr matches) `thenTc_` - - returnTc (Case expr' matches', plusLIE lie1 lie2, result_ty) - -tcExpr e (If pred b1 b2) - = tcExpr e pred `thenTc` \ (pred',lie1,predTy) -> +tc_expr (HsLet binds (L loc expr)) res_ty + = tcBindsAndThen + glue + binds -- Bindings to check + (tc_expr expr res_ty) + where + glue bind expr = HsLet [bind] (L loc expr) - unifyTauTy predTy boolTy (PredCtxt pred) `thenTc_` +tc_expr in_expr@(HsCase scrut matches) res_ty + = addErrCtxt (caseCtxt in_expr) $ - tcExpr e b1 `thenTc` \ (b1',lie2,result_ty) -> - tcExpr e b2 `thenTc` \ (b2',lie3,b2Ty) -> + -- 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 - unifyTauTy result_ty b2Ty (BranchCtxt b1 b2) `thenTc_` + tcMatchesCase match_ctxt matches res_ty `thenM` \ (scrut_ty, matches') -> - returnTc (If pred' b1' b2', plusLIE lie1 (plusLIE lie2 lie3), result_ty) + addErrCtxt (caseScrutCtxt scrut) ( + tcCheckRho scrut scrut_ty + ) `thenM` \ scrut' -> -tcExpr e (ListComp expr quals) - = mkIdsWithPolyTyVarTys binders `thenNF_Tc` \ lve -> - -- Binders of a list comprehension must be boxed. - let - new_e = growE_LVE e lve - 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) + returnM (HsCase scrut' matches') + where + match_ctxt = MC { mc_what = CaseAlt, + mc_body = tcMonoExpr } + +tc_expr (HsIf pred b1 b2) res_ty + = addErrCtxt (predCtxt pred) ( + tcCheckRho pred boolTy ) `thenM` \ pred' -> + + zapExpectedType res_ty openTypeKind `thenM` \ res_ty' -> + -- C.f. the call to zapToType in TcMatches.tcMatches + + tcCheckRho b1 res_ty' `thenM` \ b1' -> + tcCheckRho b2 res_ty' `thenM` \ b2' -> + returnM (HsIf pred' b1' b2') + +tc_expr (HsDo do_or_lc stmts method_names _) res_ty + = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' -> + -- All comprehensions yield a monotype of kind * + tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') -> + returnM (HsDo do_or_lc stmts' methods' res_ty') + +tc_expr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list + = zapToListTy res_ty `thenM` \ elt_ty -> + mappM (tc_elt elt_ty) exprs `thenM` \ exprs' -> + returnM (ExplicitList elt_ty exprs') + where + tc_elt elt_ty expr + = addErrCtxt (listCtxt expr) $ + tcCheckRho expr elt_ty + +tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty + = zapToPArrTy res_ty `thenM` \ elt_ty -> + mappM (tc_elt elt_ty) exprs `thenM` \ exprs' -> + returnM (ExplicitPArr elt_ty exprs') where - binders = collectQualBinders quals + tc_elt elt_ty expr + = addErrCtxt (parrCtxt expr) $ + tcCheckRho expr elt_ty + +tc_expr (ExplicitTuple exprs boxity) res_ty + = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys -> + tcCheckRhos exprs arg_tys `thenM` \ exprs' -> + returnM (ExplicitTuple exprs' boxity) + +tc_expr (HsProc pat cmd) res_ty + = tcProc pat cmd res_ty `thenM` \ (pat', cmd') -> + returnM (HsProc pat' cmd') \end{code} -\begin{code} -tcExpr e (ExplicitList []) - = newPolyTyVarTy `thenNF_Tc` \ tyvar_ty -> - returnTc (ExplicitListOut tyvar_ty [], nullLIE, mkListTy tyvar_ty) - - -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) - -tcExpr e (ExplicitTuple exprs) - = tcExprs e exprs `thenTc` \ (exprs', lie, tys) -> - returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys) +%************************************************************************ +%* * + Record construction and update +%* * +%************************************************************************ -tcExpr e (ArithSeqIn seq@(From expr)) - = getSrcLocTc `thenNF_Tc` \ loc -> - tcExpr e expr `thenTc` \ (expr', lie, ty) -> +\begin{code} +tc_expr expr@(RecordCon con@(L _ con_name) rbinds) res_ty + = addErrCtxt (recordConCtxt expr) $ + addLocM tcId con `thenM` \ (con_expr, con_tau) -> let - enum_from_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFrom") + (_, record_ty) = tcSplitFunTys con_tau + (tycon, ty_args) = tcSplitTyConApp record_ty in - newMethod (ArithSeqOrigin seq loc) - enum_from_id [ty] `thenNF_Tc` \ enum_from -> - - returnTc (ArithSeqOut (Var (mkInstId enum_from)) (From expr'), - plusLIE (unitLIE enum_from) lie, - mkListTy ty) + ASSERT( isAlgTyCon tycon ) + zapExpectedTo res_ty record_ty `thenM_` -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) -> + -- Check that the record bindings match the constructor + -- con_name is syntactically constrained to be a data constructor + tcLookupDataCon con_name `thenM` \ data_con -> + let + bad_fields = badFields rbinds data_con + in + if notNull bad_fields then + mappM (addErrTc . badFieldCon data_con) bad_fields `thenM_` + failM -- Fail now, because tcRecordBinds will crash on a bad field + else - unifyTauTyList [ty1, ty2] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_` + -- Typecheck the record bindings + tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' -> + + -- Check for missing fields + checkMissingFields data_con rbinds `thenM_` + + getSrcSpanM `thenM` \ loc -> + returnM (RecordConOut data_con (L loc con_expr) rbinds') + +-- The main complication with RecordUpd is that we need to explicitly +-- handle the *non-updated* fields. Consider: +-- +-- 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. + +tc_expr expr@(RecordUpd record_expr rbinds) res_ty + = addErrCtxt (recordUpdCtxt expr) $ + + -- STEP 0 + -- Check that the field names are really field names + ASSERT( notNull rbinds ) + let + field_names = map fst rbinds + in + mappM (tcLookupGlobalId.unLoc) field_names `thenM` \ sel_ids -> + -- The renamer has already checked that they + -- are all in scope + let + bad_guys = [ addSrcSpan loc $ addErrTc (notSelector field_name) + | (L loc field_name, sel_id) <- field_names `zip` sel_ids, + not (isRecordSelector sel_id) -- Excludes class ops + ] + in + checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_` + + -- STEP 1 + -- Figure out the tycon and data cons from the first field name + let + -- It's OK to use the non-tc splitters here (for a selector) + sel_id : _ = sel_ids + field_lbl = recordSelectorFieldLabel sel_id -- We've failed already if + tycon = fieldLabelTyCon field_lbl -- it's not a field label + data_cons = tyConDataCons tycon + tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars + in + tcInstTyVars VanillaTv tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) -> + + -- STEP 2 + -- Check that at least one constructor has all the named fields + -- i.e. has an empty set of bad fields returned by badFields + checkTc (any (null . badFields rbinds) data_cons) + (badFieldsUpd rbinds) `thenM_` + + -- STEP 3 + -- Typecheck the update bindings. + -- (Do this after checking for bad fields in case there's a field that + -- doesn't match the constructor.) let - enum_from_then_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromThen") + result_record_ty = mkTyConApp tycon result_inst_tys in - newMethod (ArithSeqOrigin seq loc) - enum_from_then_id [ty1] `thenNF_Tc` \ enum_from_then -> + zapExpectedTo res_ty result_record_ty `thenM_` + tcRecordBinds tycon result_inst_tys rbinds `thenM` \ rbinds' -> + + -- STEP 4 + -- Use the un-updated fields to find a vector of booleans saying + -- which type arguments must be the same in updatee and result. + -- + -- WARNING: this code assumes that all data_cons in a common tycon + -- have FieldLabels abstracted over the same tyvars. + let + upd_field_lbls = map recordSelectorFieldLabel (recBindFields rbinds') + con_field_lbls_s = map dataConFieldLabels data_cons - returnTc (ArithSeqOut (Var (mkInstId enum_from_then)) - (FromThen expr1' expr2'), - (unitLIE enum_from_then) `plusLIE` lie1 `plusLIE` lie2, - mkListTy ty1) + -- A constructor is only relevant to this process if + -- it contains all the fields that are being updated + relevant_field_lbls_s = filter is_relevant con_field_lbls_s + is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls -tcExpr e (ArithSeqIn seq@(FromTo expr1 expr2)) - = getSrcLocTc `thenNF_Tc` \ loc -> - tcExpr e expr1 `thenTc` \ (expr1',lie1,ty1) -> - tcExpr e expr2 `thenTc` \ (expr2',lie2,ty2) -> + non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls + common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls) - unifyTauTyList [ty1,ty2] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_` + mk_inst_ty (tyvar, result_inst_ty) + | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type + | otherwise = newTyVarTy liftedTypeKind -- Fresh type + in + mappM mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenM` \ inst_tys -> + + -- STEP 5 + -- Typecheck the expression to be updated let - enum_from_to_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromTo") + record_ty = mkTyConApp tycon inst_tys 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_` + tcCheckRho record_expr record_ty `thenM` \ record_expr' -> + + -- STEP 6 + -- Figure out the LIE we need. We have to generate some + -- dictionaries for the data type context, since we are going to + -- do pattern matching over the data cons. + -- + -- What dictionaries do we need? + -- We just take the context of the type constructor let - enum_from_then_to_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromThenTo") + theta' = substTheta inst_env (tyConTheta tycon) in - newMethod (ArithSeqOrigin seq loc) - enum_from_then_to_id [ty1] `thenNF_Tc` \ enum_from_then_to -> + newDicts RecordUpdOrigin theta' `thenM` \ dicts -> + extendLIEs dicts `thenM_` - 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) + -- Phew! + returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds') \end{code} + %************************************************************************ %* * -\subsection{Expressions type signatures} + Arithmetic sequences e.g. [a,b..] + and their parallel-array counterparts e.g. [: a,b.. :] + %* * %************************************************************************ \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) +tc_expr (ArithSeqIn seq@(From expr)) res_ty + = zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr elt_ty `thenM` \ expr' -> + + newMethodFromName (ArithSeqOrigin seq) + elt_ty enumFromName `thenM` \ enum_from -> + + returnM (ArithSeqOut (nlHsVar enum_from) (From expr')) + +tc_expr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty + = addErrCtxt (arithSeqCtxt in_expr) $ + zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> + newMethodFromName (ArithSeqOrigin seq) + elt_ty enumFromThenName `thenM` \ enum_from_then -> + + returnM (ArithSeqOut (nlHsVar enum_from_then) (FromThen expr1' expr2')) + + +tc_expr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty + = addErrCtxt (arithSeqCtxt in_expr) $ + zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> + newMethodFromName (ArithSeqOrigin seq) + elt_ty enumFromToName `thenM` \ enum_from_to -> + + returnM (ArithSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2')) + +tc_expr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty + = addErrCtxt (arithSeqCtxt in_expr) $ + zapToListTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> + tcCheckRho expr3 elt_ty `thenM` \ expr3' -> + newMethodFromName (ArithSeqOrigin seq) + elt_ty enumFromThenToName `thenM` \ eft -> + + returnM (ArithSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3')) + +tc_expr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty + = addErrCtxt (parrSeqCtxt in_expr) $ + zapToPArrTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> + newMethodFromName (PArrSeqOrigin seq) + elt_ty enumFromToPName `thenM` \ enum_from_to -> + + returnM (PArrSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2')) + +tc_expr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty + = addErrCtxt (parrSeqCtxt in_expr) $ + zapToPArrTy res_ty `thenM` \ elt_ty -> + tcCheckRho expr1 elt_ty `thenM` \ expr1' -> + tcCheckRho expr2 elt_ty `thenM` \ expr2' -> + tcCheckRho expr3 elt_ty `thenM` \ expr3' -> + newMethodFromName (PArrSeqOrigin seq) + elt_ty enumFromThenToPName `thenM` \ eft -> + + returnM (PArrSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3')) + +tc_expr (PArrSeqIn _) _ + = panic "TcExpr.tcMonoExpr: Infinite parallel array!" + -- the parser shouldn't have generated it and the renamer shouldn't have + -- let it through \end{code} + %************************************************************************ %* * -\subsection{Data Parallel Expressions (DPH only)} + Template Haskell %* * %************************************************************************ -Constraints enforced by the Static semantics for ParallelZF -$exp_1$ = << $exp_2$ | quals >> +\begin{code} +#ifdef GHCI /* Only if bootstrapped */ + -- Rename excludes these cases otherwise +tc_expr (HsSpliceE splice) res_ty = tcSpliceExpr splice res_ty +tc_expr (HsBracket brack) res_ty = do { e <- tcBracket brack res_ty + ; return (unLoc e) } +#endif /* GHCI */ +\end{code} -\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} + +%************************************************************************ +%* * + Catch-all +%* * +%************************************************************************ \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 -} +tc_expr other _ = pprPanic "tcMonoExpr" (ppr other) \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{@tcApp@ typchecks an application} +%* * +%************************************************************************ \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 -} + +tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args + -> Expected TcRhoType -- Expected result type of application + -> TcM (HsExpr TcId) -- Translated fun and args + +tcApp (L _ (HsApp e1 e2)) args res_ty + = tcApp e1 (e2:args) res_ty -- Accumulate the arguments + +tcApp fun args res_ty + = -- First type-check the function + tcInferRho fun `thenM` \ (fun', fun_ty) -> + + addErrCtxt (wrongArgsCtxt "too many" fun args) ( + traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_` + split_fun_ty fun_ty (length args) + ) `thenM` \ (expected_arg_tys, actual_result_ty) -> + + -- Unify with expected result before (was: after) type-checking the args + -- so that the info from res_ty (was: args) percolates to args (was actual_result_ty). + -- This is when we might detect a too-few args situation. + -- (One can think of cases when the opposite order would give + -- a better error message.) + -- [March 2003: I'm experimenting with putting this first. Here's an + -- example where it actually makes a real difference + -- class C t a b | t a -> b + -- instance C Char a Bool + -- + -- data P t a = forall b. (C t a b) => MkP b + -- data Q t = MkQ (forall a. P t a) + + -- f1, f2 :: Q Char; + -- f1 = MkQ (MkP True) + -- f2 = MkQ (MkP True :: forall a. P Char a) + -- + -- With the change, f1 will type-check, because the 'Char' info from + -- the signature is propagated into MkQ's argument. With the check + -- in the other order, the extra signature in f2 is reqd.] + + addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) + (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn -> + + -- Now typecheck the args + mappM (tcArg fun) + (zip3 args expected_arg_tys [1..]) `thenM` \ args' -> + + returnM (co_fn <$> unLoc (foldl mkHsApp fun' args')) + + +-- If an error happens we try to figure out whether the +-- function has been given too many or too few arguments, +-- and say so. +-- The ~(Check...) is because in the Infer case the tcSubExp +-- definitely won't fail, so we can be certain we're in the Check branch +checkArgsCtxt fun args ~(Check expected_res_ty) actual_res_ty tidy_env + = zonkTcType expected_res_ty `thenM` \ exp_ty' -> + zonkTcType actual_res_ty `thenM` \ act_ty' -> + let + (env1, exp_ty'') = tidyOpenType tidy_env exp_ty' + (env2, act_ty'') = tidyOpenType env1 act_ty' + (exp_args, _) = tcSplitFunTys exp_ty'' + (act_args, _) = tcSplitFunTys act_ty'' + + len_act_args = length act_args + len_exp_args = length exp_args + + message | len_exp_args < len_act_args = wrongArgsCtxt "too few" fun args + | len_exp_args > len_act_args = wrongArgsCtxt "too many" fun args + | otherwise = appCtxt fun args + in + returnM (env2, message) + + +split_fun_ty :: TcRhoType -- The type of the function + -> Int -- Number of arguments + -> TcM ([TcType], -- Function argument types + TcType) -- Function result types + +split_fun_ty fun_ty 0 + = returnM ([], fun_ty) + +split_fun_ty fun_ty n + = -- Expect the function to have type A->B + unifyFunTy fun_ty `thenM` \ (arg_ty, res_ty) -> + split_fun_ty res_ty (n-1) `thenM` \ (arg_tys, final_res_ty) -> + returnM (arg_ty:arg_tys, final_res_ty) \end{code} \begin{code} -#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 -} +tcArg :: LHsExpr Name -- The function (for error messages) + -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type + -> TcM (LHsExpr TcId) -- Resulting argument + +tcArg the_fun (arg, expected_arg_ty, arg_no) + = addErrCtxt (funAppCtxt the_fun arg arg_no) $ + tcCheckSigma arg expected_arg_ty \end{code} + %************************************************************************ %* * -\subsection{@tcExprs@ typechecks a {\em list} of expressions} +\subsection{@tcId@ typchecks an identifier occurrence} %* * %************************************************************************ -ToDo: Possibly find a version of a listTc TcM which would pass the -appropriate functions for the LIE. +tcId instantiates an occurrence of an Id. +The instantiate_it loop runs round instantiating the Id. +It has to be a loop because we are now prepared to entertain +types like + f:: forall a. Eq a => forall b. Baz b => tau +We want to instantiate this to + f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)} + +The -fno-method-sharing flag controls what happens so far as the LIE +is concerned. The default case is that for an overloaded function we +generate a "method" Id, and add the Method Inst to the LIE. So you get +something like + f :: Num a => a -> a + f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x +If you specify -fno-method-sharing, the dictionary application +isn't shared, so we get + f :: Num a => a -> a + f = /\a (d:Num a) (x:a) -> (+) a d x x +This gets a bit less sharing, but + a) it's better for RULEs involving overloaded functions + b) perhaps fewer separated lambdas \begin{code} -tcExprs :: E -> [RenamedExpr] -> TcM ([TypecheckedExpr],LIE,[TauType]) +tcId :: Name -> TcM (HsExpr TcId, TcRhoType) +tcId name -- Look up the Id and instantiate its type + = -- First check whether it's a DataCon + -- Reason: we must not forget to chuck in the + -- constraints from their "silly context" + tcLookup name `thenM` \ thing -> + case thing of { + AGlobal (ADataCon data_con) -> inst_data_con data_con + ; AGlobal (AnId id) -> loop (HsVar id) (idType id) + -- A global cannot possibly be ill-staged + -- nor does it need the 'lifting' treatment + + ; ATcId id th_level proc_level -> tc_local_id id th_level proc_level + ; other -> pprPanic "tcId" (ppr name $$ ppr thing) + } + where -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) +#ifndef GHCI + tc_local_id id th_bind_lvl proc_lvl -- Non-TH case + = checkProcLevel id proc_lvl `thenM_` + loop (HsVar id) (idType id) + +#else /* GHCI and TH is on */ + tc_local_id id th_bind_lvl proc_lvl -- TH case + = checkProcLevel id proc_lvl `thenM_` + + -- Check for cross-stage lifting + getStage `thenM` \ use_stage -> + case use_stage of + Brack use_lvl ps_var lie_var + | use_lvl > th_bind_lvl + -> -- E.g. \x -> [| h x |] + -- We must behave as if the reference to x was + + -- h $(lift x) + -- We use 'x' itself as the splice proxy, used by + -- the desugarer to stitch it all back together. + -- If 'x' occurs many times we may get many identical + -- bindings of the same splice proxy, but that doesn't + -- matter, although it's a mite untidy. + let + id_ty = idType id + in + checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_` + -- If x is polymorphic, its occurrence sites might + -- have different instantiations, so we can't use plain + -- 'x' as the splice proxy name. I don't know how to + -- solve this, and it's probably unimportant, so I'm + -- just going to flag an error for now + + setLIEVar lie_var ( + newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift -> + -- Put the 'lift' constraint into the right LIE + + -- Update the pending splices + readMutVar ps_var `thenM` \ ps -> + writeMutVar ps_var ((name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_` + + returnM (HsVar id, id_ty)) + + other -> + checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_` + loop (HsVar id) (idType id) +#endif /* GHCI */ + + loop (HsVar fun_id) fun_ty + | want_method_inst fun_ty + = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) -> + newMethodWithGivenTy orig fun_id + (mkTyVarTys tyvars) theta tau `thenM` \ meth_id -> + loop (HsVar meth_id) tau + + loop fun fun_ty + | isSigmaTy fun_ty + = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) -> + loop (inst_fn <$> fun) tau + + | otherwise + = returnM (fun, fun_ty) + + -- Hack Alert (want_method_inst)! + -- If f :: (%x :: T) => Int -> Int + -- Then if we have two separate calls, (f 3, f 4), we cannot + -- make a method constraint that then gets shared, thus: + -- let m = f %x in (m 3, m 4) + -- because that loses the linearity of the constraint. + -- The simplest thing to do is never to construct a method constraint + -- in the first place that has a linear implicit parameter in it. + want_method_inst fun_ty + | opt_NoMethodSharing = False + | otherwise = case tcSplitSigmaTy fun_ty of + (_,[],_) -> False -- Not overloaded + (_,theta,_) -> not (any isLinearPred theta) + + + -- We treat data constructors differently, because we have to generate + -- constraints for their silly theta, which no longer appears in + -- the type of dataConWrapId (see note on "stupid context" in DataCon.lhs + -- It's dual to TcPat.tcConstructor + inst_data_con data_con + = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) -> + extendLIEs ex_dicts `thenM_` + getSrcSpanM `thenM` \ loc -> + returnM (unLoc (mkHsDictApp (mkHsTyApp (L loc (HsVar (dataConWrapId data_con))) ty_args) + (map instToId ex_dicts)), + mkFunTys arg_tys result_ty) + -- ToDo: nasty loc/unloc stuff here + + orig = OccurrenceOf name \end{code} - %************************************************************************ %* * -\subsection{@tcApp@ typchecks an application} +\subsection{Record bindings} %* * %************************************************************************ -\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') -> +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. - unify_args (arg_no+1) (App fun arg'') (lie `plusLIE` lie_arg') args arg_tys fun_res_ty +For each binding field = value - 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. +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} +tcRecordBinds + :: TyCon -- Type constructor for the record + -> [TcType] -- Args of this type constructor + -> HsRecordBinds Name + -> TcM (HsRecordBinds TcId) + +tcRecordBinds tycon ty_args rbinds + = mappM do_bind rbinds + where + tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args + + do_bind (L loc field_lbl_name, rhs) + = addErrCtxt (fieldCtxt field_lbl_name) $ + tcLookupId field_lbl_name `thenM` \ sel_id -> let - result_ty = glueTyArgs arg_tys fun_res_ty + field_lbl = recordSelectorFieldLabel sel_id + field_ty = substTy tenv (fieldLabelType field_lbl) in - getSrcLocTc `thenNF_Tc` \ loc -> - checkTc (not (isTauTy result_ty)) - (underAppliedTyErr result_ty loc) `thenTc_` - returnTc (fun, lie, result_ty) + ASSERT( isRecordSelector sel_id ) + -- This lookup and assertion will surely succeed, because + -- we check that the fields are indeed record selectors + -- before calling tcRecordBinds + ASSERT2( fieldLabelTyCon field_lbl == tycon, ppr field_lbl ) + -- The caller of tcRecordBinds has already checked + -- that all the fields come from the same type + + tcCheckSigma rhs field_ty `thenM` \ rhs' -> - -- 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 + returnM (L loc sel_id, rhs') +badFields rbinds data_con + = filter (not . (`elem` field_names)) (recBindFields rbinds) + where + field_names = map fieldLabelName (dataConFieldLabels data_con) + +checkMissingFields :: DataCon -> HsRecordBinds Name -> TcM () +checkMissingFields data_con rbinds + | null field_labels -- Not declared as a record; + -- But C{} is still valid if no strict fields + = if any isMarkedStrict field_strs then + -- Illegal if any arg is strict + addErrTc (missingStrictFields data_con []) + else + returnM () + + | otherwise -- A record + = checkM (null missing_s_fields) + (addErrTc (missingStrictFields data_con missing_s_fields)) `thenM_` - unify_fun :: Int -- Current argument number - -> TypecheckedExpr -- Current rebuilt expression - -> LIE -- Corresponding LIE - -> [RenamedExpr] -- Remaining args - -> TauType -- Remaining function type - -> TcM (TypecheckedExpr, LIE, UniType) + doptM Opt_WarnMissingFields `thenM` \ warn -> + checkM (not (warn && notNull missing_ns_fields)) + (warnTc True (missingFields data_con missing_ns_fields)) - 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' -> + where + missing_s_fields + = [ fl | (fl, str) <- field_info, + isMarkedStrict str, + not (fieldLabelName fl `elem` field_names_used) + ] + missing_ns_fields + = [ fl | (fl, str) <- field_info, + not (isMarkedStrict str), + not (fieldLabelName fl `elem` field_names_used) + ] + + field_names_used = recBindFields rbinds + field_labels = dataConFieldLabels data_con + + field_info = zipEqual "missingFields" + field_labels + field_strs + + field_strs = dataConStrictMarks data_con +\end{code} - -- Now see whether it has any arguments - case (splitTyArgs fun_ty') of +%************************************************************************ +%* * +\subsection{@tcCheckRhos@ typechecks a {\em list} of expressions} +%* * +%************************************************************************ - ([], _) -> -- Function has no arguments left +\begin{code} +tcCheckRhos :: [LHsExpr Name] -> [TcType] -> TcM [LHsExpr TcId] - newOpenTyVarTy `thenNF_Tc` \ result_ty -> - tcExprs e args `thenTc` \ (args', lie_args, arg_tys) -> +tcCheckRhos [] [] = returnM [] +tcCheckRhos (expr:exprs) (ty:tys) + = tcCheckRho expr ty `thenM` \ expr' -> + tcCheckRhos exprs tys `thenM` \ exprs' -> + returnM (expr':exprs') +\end{code} - -- 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_` - returnTc (build_result_expression fun args', - lie `plusLIE` lie_args, - result_ty) +%************************************************************************ +%* * +\subsection{Literals} +%* * +%************************************************************************ - (fun_arg_tys, fun_res_ty) -> -- Function has non-empty list of argument types +Overloaded literals. - unify_args arg_no fun lie args fun_arg_tys fun_res_ty +\begin{code} +tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId) +tcLit lit res_ty + = zapExpectedTo res_ty (hsLitType lit) `thenM_` + returnM (HsLit lit) \end{code} + +%************************************************************************ +%* * +\subsection{Errors and contexts} +%* * +%************************************************************************ + +Boring and alphabetical: \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 = [] - - unifyTauTy arg_tau actual_arg_ty' err_ctxt `thenTc_` - - -- Check that the arg_tyvars havn't been constrained - -- The interesting bit here is that we must include the free variables - -- of the expected arg ty. Here's an example: - -- runST (newVar True) - -- Here, if we don't make a check, we'll get a type (ST s (MutVar s Bool)) - -- for (newVar True), with s fresh. Then we unify with the runST's arg type - -- forall s'. ST s' a. That unifies s' with s, and a with MutVar s Bool. - -- So now s' isn't unconstrained because it's linked to a. - -- Conclusion: include the free vars of the expected arg type in the - -- list of "free vars" for the signature check. - 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' -> +arithSeqCtxt expr + = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr) + +parrSeqCtxt expr + = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr) + +caseCtxt expr + = hang (ptext SLIT("In the case expression:")) 4 (ppr expr) - tcSimplifyRank2 arg_tyvars' insts' rank2_err_ctxt `thenTc` \ (free_insts, inst_binds) -> +caseScrutCtxt expr + = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr) - -- 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) +exprCtxt expr + = hang (ptext SLIT("In the expression:")) 4 (ppr expr) - | otherwise - = -- The ordinary, non-rank-2 polymorphic case - unifyTauTy expected_arg_ty actual_arg_ty err_ctxt `thenTc_` - returnTc (arg_expr, actual_arg_lie) +fieldCtxt field_name + = ptext SLIT("In the") <+> quotes (ppr field_name) <+> ptext SLIT("field of a record") +funAppCtxt fun arg arg_no + = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"), + quotes (ppr fun) <> text ", namely"]) + 4 (quotes (ppr arg)) + +listCtxt expr + = hang (ptext SLIT("In the list element:")) 4 (ppr expr) + +parrCtxt expr + = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr) + +predCtxt expr + = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr) + +appCtxt fun args + = ptext SLIT("In the application") <+> quotes (ppr the_app) where - rank2_err_ctxt = Rank2ArgCtxt arg_expr expected_arg_ty + the_app = foldl mkHsApp fun args -- Used in error messages - mk_binds [] = EmptyBinds - mk_binds ((inst,rhs):inst_binds) = (SingleBind (NonRecBind (VarMonoBind (mkInstId inst) rhs))) - `ThenBinds` - mk_binds inst_binds -\end{code} +badFieldsUpd rbinds + = hang (ptext SLIT("No constructor has all these fields:")) + 4 (pprQuotedList (recBindFields rbinds)) -This version only does not check for 2nd order if it is applied. +recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr +recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr -\begin{code} -tcExpr' :: E -> RenamedExpr -> Int -> TcM (TypecheckedExpr,LIE,UniType) +notSelector field + = hsep [quotes (ppr field), ptext SLIT("is not a record selector")] -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 +missingStrictFields :: DataCon -> [FieldLabel] -> SDoc +missingStrictFields con fields + = header <> rest + where + rest | null fields = empty -- Happens for non-record constructors + -- with strict fields + | otherwise = colon <+> pprWithCommas ppr fields + + header = ptext SLIT("Constructor") <+> quotes (ppr con) <+> + ptext SLIT("does not have the required strict field(s)") + +missingFields :: DataCon -> [FieldLabel] -> SDoc +missingFields con fields + = ptext SLIT("Fields of") <+> quotes (ppr con) <+> ptext SLIT("not initialised:") + <+> pprWithCommas ppr fields + +wrongArgsCtxt too_many_or_few fun args + = hang (ptext SLIT("Probable cause:") <+> quotes (ppr fun) + <+> ptext SLIT("is applied to") <+> text too_many_or_few + <+> ptext SLIT("arguments in the call")) + 4 (parens (ppr the_app)) + where + the_app = foldl mkHsApp fun args -- Used in error messages + +#ifdef GHCI +polySpliceErr :: Id -> SDoc +polySpliceErr id + = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id) +#endif \end{code}