X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=ghc%2Fcompiler%2Ftypecheck%2FTcMatches.lhs;h=39b4253c23c4e24eada0f3dcede08b64f7c43ea1;hb=ac10f8408520a30e8437496d320b8b86afda2e8f;hp=f29d89a7416fb74782df329bb21f553742a09cf0;hpb=479cc24837aa2c14c3bbed323bb640a5c53a2522;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcMatches.lhs b/ghc/compiler/typecheck/TcMatches.lhs index f29d89a..39b4253 100644 --- a/ghc/compiler/typecheck/TcMatches.lhs +++ b/ghc/compiler/typecheck/TcMatches.lhs @@ -5,51 +5,47 @@ \begin{code} module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda, - tcMatchPats, matchCtxt, TcMatchCtxt(..), + matchCtxt, TcMatchCtxt(..), tcStmts, tcDoStmts, - tcDoStmt, tcMDoStmt, tcGuardStmt, - tcThingWithSig + tcDoStmt, tcMDoStmt, tcGuardStmt ) where #include "HsVersions.h" -import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcCheckRho, tcInferRho, tcMonoExpr, tcCheckSigma ) +import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr ) import HsSyn ( HsExpr(..), LHsExpr, MatchGroup(..), Match(..), LMatch, GRHSs(..), GRHS(..), Stmt(..), LStmt, HsMatchContext(..), HsStmtContext(..), - LPat, pprMatch, isIrrefutableHsPat, - pprMatchContext, pprStmtContext, pprMatchRhsContext, - collectPatsBinders, noSyntaxExpr - ) -import TcHsSyn ( ExprCoFn, isIdCoercion, (<$>), (<.>) ) + pprMatch, isIrrefutableHsPat, + pprMatchContext, pprStmtContext, + noSyntaxExpr, matchGroupArity, pprMatches, + ExprCoFn ) import TcRnMonad -import TcHsType ( tcHsPatSigType, UserTypeCtxt(..) ) -import Inst ( tcInstCall, newMethodFromName ) +import TcHsType ( tcPatSig, UserTypeCtxt(..) ) +import Inst ( newMethodFromName ) import TcEnv ( TcId, tcLookupLocalIds, tcLookupId, tcExtendIdEnv, - tcExtendTyVarEnv ) -import TcPat ( PatCtxt(..), tcPats ) -import TcMType ( newTyFlexiVarTy, newTyFlexiVarTys, zonkTcType ) -import TcType ( TcType, TcTyVar, TcSigmaType, TcRhoType, mkFunTys, - tyVarsOfTypes, tidyOpenTypes, isSigmaTy, - liftedTypeKind, openTypeKind, mkFunTy, mkAppTy ) + tcExtendTyVarEnv2 ) +import TcPat ( PatCtxt(..), tcPats, tcPat ) +import TcMType ( newFlexiTyVarTy, newFlexiTyVarTys ) +import TcType ( TcType, TcRhoType, + BoxySigmaType, BoxyRhoType, + mkFunTys, mkFunTy, mkAppTy, mkTyConApp, + liftedTypeKind ) import TcBinds ( tcLocalBinds ) -import TcUnify ( Expected(..), zapExpectedType, readExpectedType, - unifyTauTy, subFunTys, unifyTyConApp, - checkSigTyVarsWrt, zapExpectedBranches, tcSubExp, tcGen, - unifyAppTy, zapToListTy, zapToTyConApp ) +import TcUnify ( boxySplitAppTy, boxySplitTyConApp, boxySplitListTy, + subFunTys, tcSubExp, withBox ) import TcSimplify ( bindInstsOfLocalFuns ) import Name ( Name ) import TysWiredIn ( stringTy, boolTy, parrTyCon, listTyCon, mkListTy, mkPArrTy ) import PrelNames ( bindMName, returnMName, mfixName, thenMName, failMName ) import Id ( idType, mkLocalId ) import TyCon ( TyCon ) -import CoreFVs ( idFreeTyVars ) -import VarSet import Util ( isSingleton ) import Outputable import SrcLoc ( Located(..) ) +import ErrUtils ( Message ) import List ( nub ) \end{code} @@ -68,8 +64,8 @@ same number of arguments before using @tcMatches@ to do the work. \begin{code} tcMatchesFun :: Name -> MatchGroup Name - -> Expected TcRhoType -- Expected type of function - -> TcM (MatchGroup TcId) -- Returns type of body + -> BoxyRhoType -- Expected type of function + -> TcM (ExprCoFn, MatchGroup TcId) -- Returns type of body tcMatchesFun fun_name matches exp_ty = do { -- Check that they all have the same no of arguments @@ -87,13 +83,14 @@ tcMatchesFun fun_name matches exp_ty -- This is one of two places places we call subFunTys -- The point is that if expected_y is a "hole", we want -- to make pat_tys and rhs_ty as "holes" too. - ; exp_ty' <- zapExpectedBranches matches exp_ty - ; subFunTys ctxt matches exp_ty' $ \ pat_tys rhs_ty -> + ; subFunTys doc n_pats exp_ty $ \ pat_tys rhs_ty -> tcMatches match_ctxt pat_tys rhs_ty matches } where - ctxt = FunRhs fun_name - match_ctxt = MC { mc_what = ctxt, mc_body = tcMonoExpr } + doc = ptext SLIT("The equation(s) for") <+> quotes (ppr fun_name) + <+> ptext SLIT("have") <+> speakNOf n_pats (ptext SLIT("argument")) + n_pats = matchGroupArity matches + match_ctxt = MC { mc_what = FunRhs fun_name, mc_body = tcPolyExpr } \end{code} @tcMatchesCase@ doesn't do the argument-count check because the @@ -103,32 +100,34 @@ parser guarantees that each equation has exactly one argument. tcMatchesCase :: TcMatchCtxt -- Case context -> TcRhoType -- Type of scrutinee -> MatchGroup Name -- The case alternatives - -> Expected TcRhoType -- Type of whole case expressions + -> BoxyRhoType -- Type of whole case expressions -> TcM (MatchGroup TcId) -- Translated alternatives -tcMatchesCase ctxt scrut_ty matches exp_ty - = do { exp_ty' <- zapExpectedBranches matches exp_ty - ; tcMatches ctxt [Check scrut_ty] exp_ty' matches } +tcMatchesCase ctxt scrut_ty matches res_ty + = tcMatches ctxt [scrut_ty] res_ty matches -tcMatchLambda :: MatchGroup Name -> Expected TcRhoType -> TcM (MatchGroup TcId) -tcMatchLambda match exp_ty -- One branch so no unifyBranches needed - = subFunTys LambdaExpr match exp_ty $ \ pat_tys rhs_ty -> +tcMatchLambda :: MatchGroup Name -> BoxyRhoType -> TcM (ExprCoFn, MatchGroup TcId) +tcMatchLambda match res_ty + = subFunTys doc n_pats res_ty $ \ pat_tys rhs_ty -> tcMatches match_ctxt pat_tys rhs_ty match where + n_pats = matchGroupArity match + doc = sep [ ptext SLIT("The lambda expression") + <+> quotes (pprSetDepth 1 $ pprMatches LambdaExpr match), + -- The pprSetDepth makes the abstraction print briefly + ptext SLIT("has") <+> speakNOf n_pats (ptext SLIT("arguments"))] match_ctxt = MC { mc_what = LambdaExpr, - mc_body = tcMonoExpr } + mc_body = tcPolyExpr } \end{code} @tcGRHSsPat@ typechecks @[GRHSs]@ that occur in a @PatMonoBind@. \begin{code} -tcGRHSsPat :: GRHSs Name - -> Expected TcRhoType - -> TcM (GRHSs TcId) -tcGRHSsPat grhss exp_ty = tcGRHSs match_ctxt grhss exp_ty +tcGRHSsPat :: GRHSs Name -> BoxyRhoType -> TcM (GRHSs TcId) +tcGRHSsPat grhss res_ty = tcGRHSs match_ctxt grhss res_ty where match_ctxt = MC { mc_what = PatBindRhs, - mc_body = tcMonoExpr } + mc_body = tcPolyExpr } \end{code} @@ -140,172 +139,69 @@ tcGRHSsPat grhss exp_ty = tcGRHSs match_ctxt grhss exp_ty \begin{code} tcMatches :: TcMatchCtxt - -> [Expected TcRhoType] -- Expected pattern types - -> Expected TcRhoType -- Expected result-type of the Match. + -> [BoxySigmaType] -- Expected pattern types + -> BoxyRhoType -- Expected result-type of the Match. -> MatchGroup Name -> TcM (MatchGroup TcId) data TcMatchCtxt -- c.f. TcStmtCtxt, also in this module = MC { mc_what :: HsMatchContext Name, -- What kind of thing this is mc_body :: LHsExpr Name -- Type checker for a body of an alternative - -> Expected TcRhoType + -> BoxyRhoType -> TcM (LHsExpr TcId) } tcMatches ctxt pat_tys rhs_ty (MatchGroup matches _) = do { matches' <- mapM (tcMatch ctxt pat_tys rhs_ty) matches - ; pat_tys' <- mapM readExpectedType pat_tys - ; rhs_ty' <- readExpectedType rhs_ty - ; return (MatchGroup matches' (mkFunTys pat_tys' rhs_ty')) } + ; return (MatchGroup matches' (mkFunTys pat_tys rhs_ty)) } ------------- tcMatch :: TcMatchCtxt - -> [Expected TcRhoType] -- Expected pattern types - -> Expected TcRhoType -- Expected result-type of the Match. + -> [BoxySigmaType] -- Expected pattern types + -> BoxyRhoType -- Expected result-type of the Match. -> LMatch Name -> TcM (LMatch TcId) tcMatch ctxt pat_tys rhs_ty match = wrapLocM (tc_match ctxt pat_tys rhs_ty) match + where + tc_match ctxt pat_tys rhs_ty match@(Match pats maybe_rhs_sig grhss) + = addErrCtxt (matchCtxt (mc_what ctxt) match) $ + do { (pats', grhss') <- tcPats LamPat pats pat_tys rhs_ty $ + tc_grhss ctxt maybe_rhs_sig grhss + ; returnM (Match pats' Nothing grhss') } -tc_match ctxt pat_tys rhs_ty match@(Match pats maybe_rhs_sig grhss) - = addErrCtxt (matchCtxt (mc_what ctxt) match) $ - do { (pats', grhss') <- tcMatchPats pats pat_tys rhs_ty $ - tc_grhss ctxt maybe_rhs_sig grhss rhs_ty - ; returnM (Match pats' Nothing grhss') } + tc_grhss ctxt Nothing grhss rhs_ty + = tcGRHSs ctxt grhss rhs_ty -- No result signature + tc_grhss ctxt (Just res_sig) grhss rhs_ty + = do { (inner_ty, sig_tvs) <- tcPatSig ResSigCtxt res_sig rhs_ty + ; tcExtendTyVarEnv2 sig_tvs $ + tcGRHSs ctxt grhss inner_ty } ------------- -tc_grhss ctxt Nothing grhss rhs_ty - = tcGRHSs ctxt grhss rhs_ty -- No result signature - -tc_grhss ctxt (Just res_sig) grhss rhs_ty - = do { (sig_tvs, sig_ty) <- tcHsPatSigType ResSigCtxt res_sig - ; traceTc (text "tc_grhss" <+> ppr sig_tvs) - ; (co_fn, grhss') <- tcExtendTyVarEnv sig_tvs $ - tcThingWithSig sig_ty (tcGRHSs ctxt grhss . Check) rhs_ty - - -- Push the coercion down to the right hand sides, - -- because there is no convenient place to hang it otherwise. - ; if isIdCoercion co_fn then - return grhss' - else - return (lift_grhss co_fn grhss') } +tcGRHSs :: TcMatchCtxt -> GRHSs Name -> BoxyRhoType -> TcM (GRHSs TcId) -------------- -lift_grhss co_fn (GRHSs grhss binds) - = GRHSs (map (fmap lift_grhs) grhss) binds - where - lift_grhs (GRHS stmts rhs) = GRHS stmts (fmap (co_fn <$>) rhs) +-- Notice that we pass in the full res_ty, so that we get +-- good inference from simple things like +-- f = \(x::forall a.a->a) -> +-- We used to force it to be a monotype when there was more than one guard +-- but we don't need to do that any more -------------- -tcGRHSs :: TcMatchCtxt -> GRHSs Name - -> Expected TcRhoType - -> TcM (GRHSs TcId) - - -- Special case when there is just one equation with a degenerate - -- guard; then we pass in the full Expected type, so that we get - -- good inference from simple things like - -- f = \(x::forall a.a->a) -> - -- This is a consequence of the fact that tcStmts takes a TcType, - -- not a Expected TcType, a decision we could revisit if necessary -tcGRHSs ctxt (GRHSs [L loc1 (GRHS [] rhs)] binds) exp_ty - = do { (binds', rhs') <- tcLocalBinds binds $ - mc_body ctxt rhs exp_ty - ; returnM (GRHSs [L loc1 (GRHS [] rhs')] binds') } - -tcGRHSs ctxt (GRHSs grhss binds) exp_ty - = do { exp_ty' <- zapExpectedType exp_ty openTypeKind - -- Even if there is only one guard, we zap the RHS type to - -- a monotype. Reason: it makes tcStmts much easier, - -- and even a one-armed guard has a notional second arm - - ; (binds', grhss') <- tcLocalBinds binds $ - mappM (wrapLocM (tcGRHS ctxt exp_ty')) grhss +tcGRHSs ctxt (GRHSs grhss binds) res_ty + = do { (binds', grhss') <- tcLocalBinds binds $ + mappM (wrapLocM (tcGRHS ctxt res_ty)) grhss ; returnM (GRHSs grhss' binds') } ------------- -tcGRHS :: TcMatchCtxt -> TcRhoType - -> GRHS Name -> TcM (GRHS TcId) +tcGRHS :: TcMatchCtxt -> BoxyRhoType -> GRHS Name -> TcM (GRHS TcId) -tcGRHS ctxt exp_ty' (GRHS guards rhs) - = do { (guards', rhs') <- tcStmts stmt_ctxt (tcGuardStmt exp_ty') guards $ - addErrCtxt (grhsCtxt match_ctxt rhs) $ - tcCheckRho rhs exp_ty' +tcGRHS ctxt res_ty (GRHS guards rhs) + = do { (guards', rhs') <- tcStmts stmt_ctxt tcGuardStmt guards res_ty $ + mc_body ctxt rhs ; return (GRHS guards' rhs') } where - match_ctxt = mc_what ctxt - stmt_ctxt = PatGuard match_ctxt -\end{code} - - -\begin{code} -tcThingWithSig :: TcSigmaType -- Type signature - -> (TcRhoType -> TcM r) -- How to type check the thing inside - -> Expected TcRhoType -- Overall expected result type - -> TcM (ExprCoFn, r) --- Used for expressions with a type signature, and for result type signatures - -tcThingWithSig sig_ty thing_inside res_ty - | not (isSigmaTy sig_ty) - = thing_inside sig_ty `thenM` \ result -> - tcSubExp res_ty sig_ty `thenM` \ co_fn -> - returnM (co_fn, result) - - | otherwise -- The signature has some outer foralls - = -- Must instantiate the outer for-alls of sig_tc_ty - -- else we risk instantiating a ? res_ty to a forall-type - -- which breaks the invariant that tcMonoExpr only returns phi-types - tcGen sig_ty emptyVarSet thing_inside `thenM` \ (gen_fn, result) -> - tcInstCall InstSigOrigin sig_ty `thenM` \ (inst_fn, _, inst_sig_ty) -> - tcSubExp res_ty inst_sig_ty `thenM` \ co_fn -> - returnM (co_fn <.> inst_fn <.> gen_fn, result) - -- Note that we generalise, then instantiate. Ah well. -\end{code} - - -%************************************************************************ -%* * -\subsection{tcMatchPats} -%* * -%************************************************************************ - -\begin{code} -tcMatchPats :: [LPat Name] - -> [Expected TcSigmaType] -- Pattern types - -> Expected TcRhoType -- Result type; - -- used only to check existential escape - -> TcM a - -> TcM ([LPat TcId], a) --- Typecheck the patterns, extend the environment to bind the variables, --- do the thing inside, use any existentially-bound dictionaries to --- discharge parts of the returning LIE, and deal with pattern type --- signatures - -tcMatchPats pats tys body_ty thing_inside - = do { (pats', ex_tvs, res) <- tcPats LamPat pats tys thing_inside - ; tcCheckExistentialPat pats' ex_tvs tys body_ty - ; returnM (pats', res) } - -tcCheckExistentialPat :: [LPat TcId] -- Patterns (just for error message) - -> [TcTyVar] -- Existentially quantified tyvars bound by pattern - -> [Expected TcSigmaType] -- Types of the patterns - -> Expected TcRhoType -- Type of the body of the match - -- Tyvars in either of these must not escape - -> TcM () - -- NB: we *must* pass "pats_tys" not just "body_ty" to tcCheckExistentialPat - -- For example, we must reject this program: - -- data C = forall a. C (a -> Int) - -- f (C g) x = g x - -- Here, result_ty will be simply Int, but expected_ty is (C -> a -> Int). - -tcCheckExistentialPat pats [] pat_tys body_ty - = return () -- Short cut for case when there are no existentials - -tcCheckExistentialPat pats ex_tvs pat_tys body_ty - = do { tys <- mapM readExpectedType (body_ty : pat_tys) - ; addErrCtxtM (sigPatCtxt (collectPatsBinders pats) ex_tvs tys) $ - checkSigTyVarsWrt (tyVarsOfTypes tys) ex_tvs } + stmt_ctxt = PatGuard (mc_what ctxt) \end{code} @@ -319,47 +215,46 @@ tcCheckExistentialPat pats ex_tvs pat_tys body_ty tcDoStmts :: HsStmtContext Name -> [LStmt Name] -> LHsExpr Name - -> Expected TcRhoType + -> BoxyRhoType -> TcM (HsExpr TcId) -- Returns a HsDo tcDoStmts ListComp stmts body res_ty - = do { elt_ty <- zapToListTy res_ty - ; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon elt_ty) stmts $ - addErrCtxt (doBodyCtxt ListComp body) $ - tcCheckRho body elt_ty + = do { elt_ty <- boxySplitListTy res_ty + ; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon) stmts elt_ty $ + tcBody (doBodyCtxt ListComp body) body ; return (HsDo ListComp stmts' body' (mkListTy elt_ty)) } tcDoStmts PArrComp stmts body res_ty - = do { [elt_ty] <- zapToTyConApp parrTyCon res_ty - ; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon elt_ty) stmts $ - addErrCtxt (doBodyCtxt PArrComp body) $ - tcCheckRho body elt_ty + = do { [elt_ty] <- boxySplitTyConApp parrTyCon res_ty + ; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts elt_ty $ + tcBody (doBodyCtxt PArrComp body) body ; return (HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) } tcDoStmts DoExpr stmts body res_ty - = do { res_ty' <- zapExpectedType res_ty liftedTypeKind - ; (m_ty, _) <- unifyAppTy res_ty' - ; (stmts', body') <- tcStmts DoExpr (tcDoStmt m_ty res_ty') stmts $ - addErrCtxt (doBodyCtxt DoExpr body) $ - tcCheckRho body res_ty' + = do { (m_ty, elt_ty) <- boxySplitAppTy res_ty + ; let res_ty' = mkAppTy m_ty elt_ty -- The boxySplit consumes res_ty + ; (stmts', body') <- tcStmts DoExpr (tcDoStmt m_ty) stmts res_ty' $ + tcBody (doBodyCtxt DoExpr body) body ; return (HsDo DoExpr stmts' body' res_ty') } -tcDoStmts cxt@(MDoExpr _) stmts body res_ty - = do { res_ty' <- zapExpectedType res_ty liftedTypeKind - ; (m_ty, _) <- unifyAppTy res_ty' - ; let tc_rhs rhs = do { (rhs', rhs_ty) <- tcInferRho rhs - ; (n_ty, pat_ty) <- unifyAppTy rhs_ty - ; unifyTauTy m_ty n_ty - ; return (rhs', pat_ty) } +tcDoStmts ctxt@(MDoExpr _) stmts body res_ty + = do { (m_ty, elt_ty) <- boxySplitAppTy res_ty + ; let res_ty' = mkAppTy m_ty elt_ty -- The boxySplit consumes res_ty + tc_rhs rhs = withBox liftedTypeKind $ \ pat_ty -> + tcMonoExpr rhs (mkAppTy m_ty pat_ty) - ; (stmts', body') <- tcStmts cxt (tcMDoStmt res_ty' tc_rhs) stmts $ - addErrCtxt (doBodyCtxt cxt body) $ - tcCheckRho body res_ty' + ; (stmts', body') <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty' $ + tcBody (doBodyCtxt ctxt body) body ; let names = [mfixName, bindMName, thenMName, returnMName, failMName] ; insts <- mapM (newMethodFromName DoOrigin m_ty) names ; return (HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') } tcDoStmts ctxt stmts body res_ty = pprPanic "tcDoStmts" (pprStmtContext ctxt) + +tcBody :: Message -> LHsExpr Name -> BoxyRhoType -> TcM (LHsExpr TcId) +tcBody ctxt body res_ty + = -- addErrCtxt ctxt $ -- This context adds little that is useful + tcPolyExpr body res_ty \end{code} @@ -373,53 +268,58 @@ tcDoStmts ctxt stmts body res_ty = pprPanic "tcDoStmts" (pprStmtContext ctxt) type TcStmtChecker = forall thing. HsStmtContext Name -> Stmt Name - -> TcM thing + -> BoxyRhoType -- Result type for comprehension + -> (BoxyRhoType -> TcM thing) -- Checker for what follows the stmt -> TcM (Stmt TcId, thing) + -- The incoming BoxyRhoType may be refined by type refinements + -- before being passed to the thing_inside + tcStmts :: HsStmtContext Name -> TcStmtChecker -- NB: higher-rank type -> [LStmt Name] - -> TcM thing + -> BoxyRhoType + -> (BoxyRhoType -> TcM thing) -> TcM ([LStmt TcId], thing) -- Note the higher-rank type. stmt_chk is applied at different -- types in the equations for tcStmts -tcStmts ctxt stmt_chk [] thing_inside - = do { thing <- thing_inside +tcStmts ctxt stmt_chk [] res_ty thing_inside + = do { thing <- thing_inside res_ty ; return ([], thing) } -- LetStmts are handled uniformly, regardless of context -tcStmts ctxt stmt_chk (L loc (LetStmt binds) : stmts) thing_inside +tcStmts ctxt stmt_chk (L loc (LetStmt binds) : stmts) res_ty thing_inside = do { (binds', (stmts',thing)) <- tcLocalBinds binds $ - tcStmts ctxt stmt_chk stmts thing_inside + tcStmts ctxt stmt_chk stmts res_ty thing_inside ; return (L loc (LetStmt binds') : stmts', thing) } -- For the vanilla case, handle the location-setting part -tcStmts ctxt stmt_chk (L loc stmt : stmts) thing_inside +tcStmts ctxt stmt_chk (L loc stmt : stmts) res_ty thing_inside = do { (stmt', (stmts', thing)) <- - setSrcSpan loc $ - addErrCtxt (stmtCtxt ctxt stmt) $ - stmt_chk ctxt stmt $ - popErrCtxt $ - tcStmts ctxt stmt_chk stmts $ + setSrcSpan loc $ + addErrCtxt (stmtCtxt ctxt stmt) $ + stmt_chk ctxt stmt res_ty $ \ res_ty' -> + popErrCtxt $ + tcStmts ctxt stmt_chk stmts res_ty' $ thing_inside ; return (L loc stmt' : stmts', thing) } -------------------------------- -- Pattern guards -tcGuardStmt :: TcType -> TcStmtChecker -tcGuardStmt res_ty ctxt (ExprStmt guard _ _) thing_inside - = do { guard' <- tcCheckRho guard boolTy - ; thing <- thing_inside +tcGuardStmt :: TcStmtChecker +tcGuardStmt ctxt (ExprStmt guard _ _) res_ty thing_inside + = do { guard' <- tcMonoExpr guard boolTy + ; thing <- thing_inside res_ty ; return (ExprStmt guard' noSyntaxExpr boolTy, thing) } -tcGuardStmt res_ty ctxt (BindStmt pat rhs _ _) thing_inside +tcGuardStmt ctxt (BindStmt pat rhs _ _) res_ty thing_inside = do { (rhs', rhs_ty) <- tcInferRho rhs - ; (pat', thing) <- tcBindPat pat rhs_ty res_ty thing_inside + ; (pat', thing) <- tcPat LamPat pat rhs_ty res_ty thing_inside ; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) } -tcGuardStmt res_ty ctxt stmt thing_inside +tcGuardStmt ctxt stmt res_ty thing_inside = pprPanic "tcGuardStmt: unexpected Stmt" (ppr stmt) @@ -427,20 +327,19 @@ tcGuardStmt res_ty ctxt stmt thing_inside -- List comprehensions and PArrays tcLcStmt :: TyCon -- The list/Parray type constructor ([] or PArray) - -> TcType -- The element type of the list or PArray -> TcStmtChecker -- A generator, pat <- rhs -tcLcStmt m_tc elt_ty ctxt (BindStmt pat rhs _ _) thing_inside - = do { (rhs', rhs_ty) <- tcInferRho rhs - ; [pat_ty] <- unifyTyConApp m_tc rhs_ty - ; (pat', thing) <- tcBindPat pat pat_ty elt_ty thing_inside +tcLcStmt m_tc ctxt (BindStmt pat rhs _ _) res_ty thing_inside + = do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ ty -> + tcMonoExpr rhs (mkTyConApp m_tc [ty]) + ; (pat', thing) <- tcPat LamPat pat pat_ty res_ty thing_inside ; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) } -- A boolean guard -tcLcStmt m_tc elt_ty ctxt (ExprStmt rhs _ _) thing_inside - = do { rhs' <- tcCheckRho rhs boolTy - ; thing <- thing_inside +tcLcStmt m_tc ctxt (ExprStmt rhs _ _) res_ty thing_inside + = do { rhs' <- tcMonoExpr rhs boolTy + ; thing <- thing_inside res_ty ; return (ExprStmt rhs' noSyntaxExpr boolTy, thing) } -- A parallel set of comprehensions @@ -464,23 +363,23 @@ tcLcStmt m_tc elt_ty ctxt (ExprStmt rhs _ _) thing_inside -- So the binders of the first parallel group will be in scope in the second -- group. But that's fine; there's no shadowing to worry about. -tcLcStmt m_tc elt_ty ctxt (ParStmt bndr_stmts_s) thing_inside +tcLcStmt m_tc ctxt (ParStmt bndr_stmts_s) elt_ty thing_inside = do { (pairs', thing) <- loop bndr_stmts_s ; return (ParStmt pairs', thing) } where -- loop :: [([LStmt Name], [Name])] -> TcM ([([LStmt TcId], [TcId])], thing) - loop [] = do { thing <- thing_inside - ; return ([], thing) } + loop [] = do { thing <- thing_inside elt_ty -- No refinement from pattern + ; return ([], thing) } -- matching in the branches loop ((stmts, names) : pairs) = do { (stmts', (ids, pairs', thing)) - <- tcStmts ctxt (tcLcStmt m_tc elt_ty) stmts $ + <- tcStmts ctxt (tcLcStmt m_tc) stmts elt_ty $ \ elt_ty' -> do { ids <- tcLookupLocalIds names ; (pairs', thing) <- loop pairs ; return (ids, pairs', thing) } ; return ( (stmts', ids) : pairs', thing ) } -tcLcStmt m_tc elt_ty ctxt stmt thing_inside +tcLcStmt m_tc ctxt stmt elt_ty thing_inside = pprPanic "tcLcStmt: unexpected Stmt" (ppr stmt) -------------------------------- @@ -488,12 +387,11 @@ tcLcStmt m_tc elt_ty ctxt stmt thing_inside -- The main excitement here is dealing with rebindable syntax tcDoStmt :: TcType -- Monad type, m - -> TcType -- Result type, m b -> TcStmtChecker - -- BindStmt -tcDoStmt m_ty res_ty ctxt (BindStmt pat rhs bind_op fail_op) thing_inside - = do { -- Deal with rebindable syntax; (>>=) :: m a -> (a -> m b) -> m b - ; (rhs', rhs_ty) <- tcInferRho rhs + +tcDoStmt m_ty ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside + = do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ pat_ty -> + tcMonoExpr rhs (mkAppTy m_ty pat_ty) -- We should use type *inference* for the RHS computations, becuase of GADTs. -- do { pat <- rhs; } -- is rather like @@ -501,13 +399,11 @@ tcDoStmt m_ty res_ty ctxt (BindStmt pat rhs bind_op fail_op) thing_inside -- We do inference on rhs, so that information about its type can be refined -- when type-checking the pattern. - ; (n_ty, pat_ty) <- unifyAppTy rhs_ty - ; unifyTauTy m_ty n_ty - ; let bind_ty = mkFunTys [rhs_ty, mkFunTy pat_ty res_ty] res_ty - - ; (pat', thing) <- tcBindPat pat pat_ty res_ty thing_inside + ; (pat', thing) <- tcPat LamPat pat pat_ty res_ty thing_inside - -- Rebindable syntax stuff + -- Deal with rebindable syntax; (>>=) :: m a -> (a -> m b) -> m b + ; let bind_ty = mkFunTys [mkAppTy m_ty pat_ty, + mkFunTy pat_ty res_ty] res_ty ; bind_op' <- tcSyntaxOp DoOrigin bind_op bind_ty -- If (but only if) the pattern can fail, -- typecheck the 'fail' operator @@ -517,17 +413,17 @@ tcDoStmt m_ty res_ty ctxt (BindStmt pat rhs bind_op fail_op) thing_inside ; return (BindStmt pat' rhs' bind_op' fail_op', thing) } -tcDoStmt m_ty res_ty ctxt (ExprStmt rhs then_op _) thing_inside +tcDoStmt m_ty ctxt (ExprStmt rhs then_op _) res_ty thing_inside = do { -- Deal with rebindable syntax; (>>) :: m a -> m b -> m b - a_ty <- newTyFlexiVarTy liftedTypeKind + a_ty <- newFlexiTyVarTy liftedTypeKind ; let rhs_ty = mkAppTy m_ty a_ty then_ty = mkFunTys [rhs_ty, res_ty] res_ty ; then_op' <- tcSyntaxOp DoOrigin then_op then_ty - ; rhs' <- tcCheckSigma rhs rhs_ty - ; thing <- thing_inside + ; rhs' <- tcPolyExpr rhs rhs_ty + ; thing <- thing_inside res_ty ; return (ExprStmt rhs' then_op' rhs_ty, thing) } -tcDoStmt m_ty res_ty ctxt stmt thing_inside +tcDoStmt m_ty ctxt stmt res_ty thing_inside = pprPanic "tcDoStmt: unexpected Stmt" (ppr stmt) -------------------------------- @@ -536,31 +432,30 @@ tcDoStmt m_ty res_ty ctxt stmt thing_inside -- (a) RecStmts, and -- (b) no rebindable syntax -tcMDoStmt :: TcType -- Result type, m b - -> (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference +tcMDoStmt :: (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference -> TcStmtChecker -tcMDoStmt res_ty tc_rhs ctxt (BindStmt pat rhs bind_op fail_op) thing_inside +tcMDoStmt tc_rhs ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside = do { (rhs', pat_ty) <- tc_rhs rhs - ; (pat', thing) <- tcBindPat pat pat_ty res_ty thing_inside + ; (pat', thing) <- tcPat LamPat pat pat_ty res_ty thing_inside ; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) } -tcMDoStmt res_ty tc_rhs ctxt (ExprStmt rhs then_op _) thing_inside +tcMDoStmt tc_rhs ctxt (ExprStmt rhs then_op _) res_ty thing_inside = do { (rhs', elt_ty) <- tc_rhs rhs - ; thing <- thing_inside + ; thing <- thing_inside res_ty ; return (ExprStmt rhs' noSyntaxExpr elt_ty, thing) } -tcMDoStmt res_ty tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) thing_inside - = do { rec_tys <- newTyFlexiVarTys (length recNames) liftedTypeKind +tcMDoStmt tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) res_ty thing_inside + = do { rec_tys <- newFlexiTyVarTys (length recNames) liftedTypeKind ; let rec_ids = zipWith mkLocalId recNames rec_tys ; tcExtendIdEnv rec_ids $ do { (stmts', (later_ids, rec_rets)) - <- tcStmts ctxt (tcMDoStmt res_ty tc_rhs) stmts $ + <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ res_ty' -> -- ToDo: res_ty not really right do { rec_rets <- zipWithM tc_ret recNames rec_tys ; later_ids <- tcLookupLocalIds laterNames ; return (later_ids, rec_rets) } - ; (thing,lie) <- tcExtendIdEnv later_ids (getLIE thing_inside) + ; (thing,lie) <- tcExtendIdEnv later_ids (getLIE (thing_inside res_ty)) -- NB: The rec_ids for the recursive things -- already scope over this part. This binding may shadow -- some of them with polymorphic things with the same Name @@ -572,24 +467,15 @@ tcMDoStmt res_ty tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) thing_insid where -- Unify the types of the "final" Ids with those of "knot-tied" Ids tc_ret rec_name mono_ty - = tcLookupId rec_name `thenM` \ poly_id -> + = do { poly_id <- tcLookupId rec_name -- poly_id may have a polymorphic type -- but mono_ty is just a monomorphic type variable - tcSubExp (Check mono_ty) (idType poly_id) `thenM` \ co_fn -> - returnM (co_fn <$> HsVar poly_id) + ; co_fn <- tcSubExp (idType poly_id) mono_ty + ; return (HsCoerce co_fn (HsVar poly_id)) } -tcMDoStmt res_ty tc_rhs ctxt stmt thing_inside +tcMDoStmt tc_rhs ctxt stmt res_ty thing_inside = pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt) ------------------ -tcBindPat :: LPat Name -> TcType - -> TcType -- Result type; used only to check existential escape - -> TcM a - -> TcM (LPat TcId, a) -tcBindPat pat pat_ty res_ty thing_inside - = do { ([pat'],thing) <- tcMatchPats [pat] [Check pat_ty] - (Check res_ty) thing_inside - ; return (pat', thing) } \end{code} @@ -618,33 +504,10 @@ varyingArgsErr name matches matchCtxt ctxt match = hang (ptext SLIT("In") <+> pprMatchContext ctxt <> colon) 4 (pprMatch ctxt match) -grhsCtxt ctxt rhs = hang (ptext SLIT("In") <+> pprMatchRhsContext ctxt <> colon) - 4 (ppr rhs) - doBodyCtxt :: HsStmtContext Name -> LHsExpr Name -> SDoc doBodyCtxt ctxt body = hang (ptext SLIT("In the result of") <+> pprStmtContext ctxt <> colon) 4 (ppr body) stmtCtxt ctxt stmt = hang (ptext SLIT("In") <+> pprStmtContext ctxt <> colon) 4 (ppr stmt) - -sigPatCtxt bound_ids bound_tvs tys tidy_env - = -- tys is (body_ty : pat_tys) - mapM zonkTcType tys `thenM` \ tys' -> - let - (env1, tidy_tys) = tidyOpenTypes tidy_env (map idType show_ids) - (_env2, tidy_body_ty : tidy_pat_tys) = tidyOpenTypes env1 tys' - in - returnM (env1, - sep [ptext SLIT("When checking an existential match that binds"), - nest 4 (vcat (zipWith ppr_id show_ids tidy_tys)), - ptext SLIT("The pattern(s) have type(s):") <+> vcat (map ppr tidy_pat_tys), - ptext SLIT("The body has type:") <+> ppr tidy_body_ty - ]) - where - show_ids = filter is_interesting bound_ids - is_interesting id = any (`elemVarSet` idFreeTyVars id) bound_tvs - - ppr_id id ty = ppr id <+> dcolon <+> ppr ty - -- Don't zonk the types so we get the separate, un-unified versions \end{code}