X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcMatches.lhs;h=452bae792d2c8521f4a91ad1b925cc4d0e7f74e0;hp=d9146d9041297398e858ccd900b8dc077c385902;hb=58de6cb725982dd1f57803cc838f233d5fd9c42c;hpb=e6d057711f4d6d6ff6342c39fa2b9e44d25447f1 diff --git a/compiler/typecheck/TcMatches.lhs b/compiler/typecheck/TcMatches.lhs index d9146d9..452bae7 100644 --- a/compiler/typecheck/TcMatches.lhs +++ b/compiler/typecheck/TcMatches.lhs @@ -1,9 +1,18 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % -\section[TcMatches]{Typecheck some @Matches@} + +TcMatches: Typecheck some @Matches@ \begin{code} +{-# OPTIONS -w #-} +-- The above warning supression flag is a temporary kludge. +-- While working on this module you are encouraged to remove it and fix +-- any warnings in the module. See +-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings +-- for details + module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda, matchCtxt, TcMatchCtxt(..), tcStmts, tcDoStmts, tcBody, @@ -14,36 +23,28 @@ module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda, import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr ) -import HsSyn ( HsExpr(..), LHsExpr, MatchGroup(..), - Match(..), LMatch, GRHSs(..), GRHS(..), - Stmt(..), LStmt, HsMatchContext(..), - HsStmtContext(..), - pprMatch, isIrrefutableHsPat, mkHsWrap, - mkLHsWrap, pprMatchContext, pprStmtContext, - noSyntaxExpr, matchGroupArity, pprMatches, - HsWrapper ) - +import HsSyn import TcRnMonad -import TcGadt ( Refinement, emptyRefinement, refineResType ) -import Inst ( newMethodFromName ) -import TcEnv ( TcId, tcLookupLocalIds, tcLookupId, tcExtendIdEnv ) -import TcPat ( tcLamPats, tcLamPat ) -import TcMType ( newFlexiTyVarTy, newFlexiTyVarTys ) -import TcType ( TcType, TcRhoType, - BoxySigmaType, BoxyRhoType, - mkFunTys, mkFunTy, mkAppTy, mkTyConApp, - liftedTypeKind ) -import TcBinds ( tcLocalBinds ) -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 TcGadt +import Inst +import TcEnv +import TcPat +import TcMType +import TcType +import TcBinds +import TcUnify +import TcSimplify +import Name +import TysWiredIn +import PrelNames +import Id +import TyCon +import TysPrim import Outputable -import SrcLoc ( Located(..), getLoc ) +import Util +import SrcLoc + +import Control.Monad \end{code} %************************************************************************ @@ -58,12 +59,12 @@ is used in error messages. It checks that all the equations have the same number of arguments before using @tcMatches@ to do the work. \begin{code} -tcMatchesFun :: Name +tcMatchesFun :: Name -> Bool -> MatchGroup Name -> BoxyRhoType -- Expected type of function -> TcM (HsWrapper, MatchGroup TcId) -- Returns type of body -tcMatchesFun fun_name matches exp_ty +tcMatchesFun fun_name inf matches exp_ty = do { -- Check that they all have the same no of arguments -- Location is in the monad, set the caller so that -- any inter-equation error messages get some vaguely @@ -86,7 +87,7 @@ tcMatchesFun fun_name matches exp_ty 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 = tcBody } + match_ctxt = MC { mc_what = FunRhs fun_name inf, mc_body = tcBody } \end{code} @tcMatchesCase@ doesn't do the argument-count check because the @@ -109,7 +110,7 @@ tcMatchLambda match res_ty where n_pats = matchGroupArity match doc = sep [ ptext SLIT("The lambda expression") - <+> quotes (pprSetDepth 1 $ pprMatches LambdaExpr match), + <+> quotes (pprSetDepth 1 $ pprMatches (LambdaExpr :: HsMatchContext Name) match), -- The pprSetDepth makes the abstraction print briefly ptext SLIT("has") <+> speakNOf n_pats (ptext SLIT("argument"))] match_ctxt = MC { mc_what = LambdaExpr, @@ -163,7 +164,7 @@ 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) $ + = add_match_ctxt match $ do { (pats', grhss') <- tcLamPats pats pat_tys rhs_ty $ tc_grhss ctxt maybe_rhs_sig grhss ; return (Match pats' Nothing grhss') } @@ -177,6 +178,13 @@ tcMatch ctxt pat_tys rhs_ty match <+> ppr res_sig) ; tcGRHSs ctxt grhss (co, rhs_ty) } + -- For (\x -> e), tcExpr has already said "In the expresssion \x->e" + -- so we don't want to add "In the lambda abstraction \x->e" + add_match_ctxt match thing_inside + = case mc_what ctxt of + LambdaExpr -> thing_inside + m_ctxt -> addErrCtxt (matchCtxt m_ctxt match) thing_inside + ------------- tcGRHSs :: TcMatchCtxt -> GRHSs Name -> (Refinement, BoxyRhoType) -> TcM (GRHSs TcId) @@ -189,9 +197,9 @@ tcGRHSs :: TcMatchCtxt -> GRHSs Name -> (Refinement, BoxyRhoType) tcGRHSs ctxt (GRHSs grhss binds) res_ty = do { (binds', grhss') <- tcLocalBinds binds $ - mappM (wrapLocM (tcGRHS ctxt res_ty)) grhss + mapM (wrapLocM (tcGRHS ctxt res_ty)) grhss - ; returnM (GRHSs grhss' binds') } + ; return (GRHSs grhss' binds') } ------------- tcGRHS :: TcMatchCtxt -> (Refinement, BoxyRhoType) -> GRHS Name -> TcM (GRHS TcId) @@ -218,29 +226,29 @@ tcDoStmts :: HsStmtContext Name -> BoxyRhoType -> TcM (HsExpr TcId) -- Returns a HsDo tcDoStmts ListComp stmts body res_ty - = do { elt_ty <- boxySplitListTy res_ty + = do { (elt_ty, coi) <- boxySplitListTy res_ty ; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon) stmts (emptyRefinement,elt_ty) $ tcBody body - ; return (HsDo ListComp stmts' body' (mkListTy elt_ty)) } + ; return $ mkHsWrapCoI coi + (HsDo ListComp stmts' body' (mkListTy elt_ty)) } tcDoStmts PArrComp stmts body res_ty - = do { [elt_ty] <- boxySplitTyConApp parrTyCon res_ty + = do { (elt_ty, coi) <- boxySplitPArrTy res_ty ; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts (emptyRefinement, elt_ty) $ tcBody body - ; return (HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) } + ; return $ mkHsWrapCoI coi + (HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) } tcDoStmts DoExpr 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 - ; (stmts', body') <- tcStmts DoExpr (tcDoStmt m_ty) stmts - (emptyRefinement, res_ty') $ + = do { (stmts', body') <- tcStmts DoExpr tcDoStmt stmts + (emptyRefinement, res_ty) $ tcBody body - ; return (HsDo DoExpr stmts' body' res_ty') } + ; return (HsDo DoExpr stmts' body' res_ty) } tcDoStmts ctxt@(MDoExpr _) stmts body res_ty - = do { (m_ty, elt_ty) <- boxySplitAppTy res_ty + = do { ((m_ty, elt_ty), coi) <- 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) @@ -251,7 +259,9 @@ tcDoStmts ctxt@(MDoExpr _) stmts body res_ty ; let names = [mfixName, bindMName, thenMName, returnMName, failMName] ; insts <- mapM (newMethodFromName DoOrigin m_ty) names - ; return (HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') } + ; return $ + mkHsWrapCoI coi + (HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') } tcDoStmts ctxt stmts body res_ty = pprPanic "tcDoStmts" (pprStmtContext ctxt) @@ -385,19 +395,80 @@ tcLcStmt m_tc ctxt (ParStmt bndr_stmts_s) elt_ty thing_inside ; return (ids, pairs', thing) } ; return ( (stmts', ids) : pairs', thing ) } +tcLcStmt m_tc ctxt (TransformStmt (stmts, binders) usingExpr maybeByExpr) elt_ty thing_inside = do + (stmts', (binders', usingExpr', maybeByExpr', thing)) <- + tcStmts (TransformStmtCtxt ctxt) (tcLcStmt m_tc) stmts elt_ty $ \elt_ty' -> do + let alphaListTy = mkTyConApp m_tc [alphaTy] + + (usingExpr', maybeByExpr') <- + case maybeByExpr of + Nothing -> do + -- We must validate that usingExpr :: forall a. [a] -> [a] + usingExpr' <- tcPolyExpr usingExpr (mkForAllTy alphaTyVar (alphaListTy `mkFunTy` alphaListTy)) + return (usingExpr', Nothing) + Just byExpr -> do + -- We must infer a type such that e :: t and then check that usingExpr :: forall a. (a -> t) -> [a] -> [a] + (byExpr', tTy) <- tcInferRho byExpr + usingExpr' <- tcPolyExpr usingExpr (mkForAllTy alphaTyVar ((alphaTy `mkFunTy` tTy) `mkFunTy` (alphaListTy `mkFunTy` alphaListTy))) + return (usingExpr', Just byExpr') + + binders' <- tcLookupLocalIds binders + thing <- thing_inside elt_ty' + + return (binders', usingExpr', maybeByExpr', thing) + + return (TransformStmt (stmts', binders') usingExpr' maybeByExpr', thing) + +tcLcStmt m_tc ctxt (GroupStmt (stmts, bindersMap) groupByClause) elt_ty thing_inside = do + (stmts', (bindersMap', groupByClause', thing)) <- + tcStmts (TransformStmtCtxt ctxt) (tcLcStmt m_tc) stmts elt_ty $ \elt_ty' -> do + let alphaListTy = mkTyConApp m_tc [alphaTy] + alphaListListTy = mkTyConApp m_tc [alphaListTy] + + groupByClause' <- + case groupByClause of + GroupByNothing usingExpr -> + -- We must validate that usingExpr :: forall a. [a] -> [[a]] + tcPolyExpr usingExpr (mkForAllTy alphaTyVar (alphaListTy `mkFunTy` alphaListListTy)) >>= (return . GroupByNothing) + GroupBySomething eitherUsingExpr byExpr -> do + -- We must infer a type such that byExpr :: t + (byExpr', tTy) <- tcInferRho byExpr + + -- If it exists, we then check that usingExpr :: forall a. (a -> t) -> [a] -> [[a]] + let expectedUsingType = mkForAllTy alphaTyVar ((alphaTy `mkFunTy` tTy) `mkFunTy` (alphaListTy `mkFunTy` alphaListListTy)) + eitherUsingExpr' <- + case eitherUsingExpr of + Left usingExpr -> (tcPolyExpr usingExpr expectedUsingType) >>= (return . Left) + Right usingExpr -> (tcPolyExpr (noLoc usingExpr) expectedUsingType) >>= (return . Right . unLoc) + return $ GroupBySomething eitherUsingExpr' byExpr' + + -- Find the IDs and types of all old binders + let (oldBinders, newBinders) = unzip bindersMap + oldBinders' <- tcLookupLocalIds oldBinders + + -- Ensure that every old binder of type b is linked up with its new binder which should have type [b] + let newBinders' = zipWith associateNewBinder oldBinders' newBinders + + -- Type check the thing in the environment with these new binders and return the result + thing <- tcExtendIdEnv newBinders' (thing_inside elt_ty') + return (zipEqual "tcLcStmt: Old and new binder lists were not of the same length" oldBinders' newBinders', groupByClause', thing) + + return (GroupStmt (stmts', bindersMap') groupByClause', thing) + where + associateNewBinder :: TcId -> Name -> TcId + associateNewBinder oldBinder newBinder = mkLocalId newBinder (mkTyConApp m_tc [idType oldBinder]) + tcLcStmt m_tc ctxt stmt elt_ty thing_inside = pprPanic "tcLcStmt: unexpected Stmt" (ppr stmt) - + -------------------------------- -- Do-notation -- The main excitement here is dealing with rebindable syntax -tcDoStmt :: TcType -- Monad type, m - -> TcStmtChecker +tcDoStmt :: TcStmtChecker -tcDoStmt m_ty ctxt (BindStmt pat rhs bind_op fail_op) reft_res_ty@(_,res_ty) thing_inside - = do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ pat_ty -> - tcMonoExpr rhs (mkAppTy m_ty pat_ty) +tcDoStmt ctxt (BindStmt pat rhs bind_op fail_op) (reft,res_ty) thing_inside + = do { (rhs', rhs_ty) <- tcInferRho rhs -- We should use type *inference* for the RHS computations, becuase of GADTs. -- do { pat <- rhs; } -- is rather like @@ -405,31 +476,45 @@ tcDoStmt m_ty ctxt (BindStmt pat rhs bind_op fail_op) reft_res_ty@(_,res_ty) thi -- We do inference on rhs, so that information about its type can be refined -- when type-checking the pattern. - ; (pat', thing) <- tcLamPat pat pat_ty reft_res_ty thing_inside + -- Deal with rebindable syntax: + -- (>>=) :: rhs_ty -> (pat_ty -> new_res_ty) -> res_ty + -- This level of generality is needed for using do-notation + -- in full generality; see Trac #1537 + ; ((bind_op', new_res_ty), pat_ty) <- + withBox liftedTypeKind $ \ pat_ty -> + withBox liftedTypeKind $ \ new_res_ty -> + tcSyntaxOp DoOrigin bind_op + (mkFunTys [rhs_ty, mkFunTy pat_ty new_res_ty] res_ty) - -- 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 - ; fail_op' <- if isIrrefutableHsPat pat' + ; fail_op' <- if isIrrefutableHsPat pat then return noSyntaxExpr - else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy res_ty) + else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy new_res_ty) + + ; (pat', thing) <- tcLamPat pat pat_ty (reft, new_res_ty) thing_inside + ; return (BindStmt pat' rhs' bind_op' fail_op', thing) } -tcDoStmt m_ty ctxt (ExprStmt rhs then_op _) reft_res_ty@(_,res_ty) thing_inside - = do { -- Deal with rebindable syntax; (>>) :: m a -> m b -> m b - 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' <- tcPolyExpr rhs rhs_ty - ; thing <- thing_inside reft_res_ty +tcDoStmt ctxt (ExprStmt rhs then_op _) (reft,res_ty) thing_inside + = do { (rhs', rhs_ty) <- tcInferRho rhs + + -- Deal with rebindable syntax; (>>) :: rhs_ty -> new_res_ty -> res_ty + ; (then_op', new_res_ty) <- + withBox liftedTypeKind $ \ new_res_ty -> + tcSyntaxOp DoOrigin then_op + (mkFunTys [rhs_ty, new_res_ty] res_ty) + + ; thing <- thing_inside (reft, new_res_ty) ; return (ExprStmt rhs' then_op' rhs_ty, thing) } -tcDoStmt m_ty ctxt stmt res_ty thing_inside +tcDoStmt ctxt (RecStmt {}) res_ty thing_inside + = failWithTc (ptext SLIT("Illegal 'rec' stmt in") <+> pprStmtContext ctxt) + -- This case can't be caught in the renamer + -- see RnExpr.checkRecStmt + +tcDoStmt ctxt stmt res_ty thing_inside = pprPanic "tcDoStmt: unexpected Stmt" (ppr stmt) -------------------------------- @@ -476,7 +561,7 @@ tcMDoStmt tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) res_ty thing_insid = do { poly_id <- tcLookupId rec_name -- poly_id may have a polymorphic type -- but mono_ty is just a monomorphic type variable - ; co_fn <- tcSubExp (idType poly_id) mono_ty + ; co_fn <- tcSubExp DoOrigin (idType poly_id) mono_ty ; return (mkHsWrap co_fn (HsVar poly_id)) } tcMDoStmt tc_rhs ctxt stmt res_ty thing_inside