X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcMatches.lhs;h=20c2a44a49e4c18d61a79282a68b64ba90bf41c0;hb=2c6d73e2ca9a545c4295c6f532cd3612e7fd3d8d;hp=484aa3c6e38ad0cfdc5bcbbd5f990d88e8d7f096;hpb=49bb45807fe94e432224601483cf3577b3f3fb7b;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcMatches.lhs b/ghc/compiler/typecheck/TcMatches.lhs index 484aa3c..20c2a44 100644 --- a/ghc/compiler/typecheck/TcMatches.lhs +++ b/ghc/compiler/typecheck/TcMatches.lhs @@ -1,40 +1,45 @@ -\% +% % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcMatches]{Typecheck some @Matches@} \begin{code} -module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatchLambda, tcStmts, tcGRHSs ) where +module TcMatches ( tcMatchesFun, tcMatchesCase, tcMatchLambda, + tcStmts, tcStmtsAndThen, tcGRHSs + ) where #include "HsVersions.h" import {-# SOURCE #-} TcExpr( tcExpr ) import HsSyn ( HsBinds(..), Match(..), GRHSs(..), GRHS(..), - MonoBinds(..), StmtCtxt(..), Stmt(..), - pprMatch, getMatchLoc, consLetStmt, - mkMonoBind + MonoBinds(..), Stmt(..), HsMatchContext(..), HsDoContext(..), + pprMatch, getMatchLoc, pprMatchContext, isDoExpr, + mkMonoBind, nullMonoBinds, collectSigTysFromPats ) -import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt ) -import TcHsSyn ( TcMatch, TcGRHSs, TcStmt ) +import RnHsSyn ( RenamedMatch, RenamedGRHSs, RenamedStmt, RenamedPat, RenamedHsType, + RenamedMatchContext, extractHsTyVars ) +import TcHsSyn ( TcMatch, TcGRHSs, TcStmt, TcDictBinds, TypecheckedPat, TypecheckedMatchContext ) import TcMonad -import TcMonoType ( checkSigTyVars, tcHsTyVar, tcHsType, sigPatCtxt ) -import Inst ( Inst, LIE, plusLIE, emptyLIE, plusLIEs ) -import TcEnv ( tcExtendLocalValEnv, tcExtendGlobalTyVars, tcExtendTyVarEnv, tcGetGlobalTyVars ) -import TcPat ( tcPat, tcPatBndr_NoSigs, polyPatSig ) -import TcType ( TcType, newTyVarTy, newTyVarTy_OpenKind, zonkTcTyVars ) +import TcMonoType ( kcHsSigTypes, tcScopedTyVars, checkSigTyVars, tcHsSigType, sigPatCtxt ) +import Inst ( LIE, isEmptyLIE, plusLIE, emptyLIE, plusLIEs, lieToList ) +import TcEnv ( TcId, tcLookupLocalIds, tcExtendLocalValEnv, tcExtendGlobalTyVars, + tcInLocalScope ) +import TcPat ( tcPat, tcMonoPatBndr, polyPatSig ) +import TcType ( TcType, newTyVarTy ) import TcBinds ( tcBindsAndThen ) -import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) +import TcSimplify ( tcSimplifyCheck, bindInstsOfLocalFuns ) import TcUnify ( unifyFunTy, unifyTauTy ) import Name ( Name ) import TysWiredIn ( boolTy ) - +import Id ( idType ) import BasicTypes ( RecFlag(..) ) -import Type ( Kind, tyVarsOfType, isTauTy, mkFunTy, boxedTypeKind ) +import Type ( tyVarsOfType, isTauTy, mkFunTy, + liftedTypeKind, openTypeKind, splitSigmaTy ) +import NameSet import VarSet import Var ( Id ) -import Util import Bag import Outputable import List ( nub ) @@ -56,7 +61,7 @@ tcMatchesFun :: [(Name,Id)] -- Bindings for the variables bound in this group -> Name -> TcType -- Expected type -> [RenamedMatch] - -> TcM s ([TcMatch], LIE) + -> TcM ([TcMatch], LIE) tcMatchesFun xve fun_name expected_ty matches@(first_match:_) = -- Check that they all have the same no of arguments @@ -75,7 +80,7 @@ tcMatchesFun xve fun_name expected_ty matches@(first_match:_) -- may show up as something wrong with the (non-existent) type signature -- No need to zonk expected_ty, because unifyFunTy does that on the fly - tcMatches xve matches expected_ty (FunRhs fun_name) + tcMatches xve (FunRhs fun_name) matches expected_ty \end{code} @tcMatchesCase@ doesn't do the argument-count check because the @@ -84,32 +89,32 @@ parser guarantees that each equation has exactly one argument. \begin{code} tcMatchesCase :: [RenamedMatch] -- The case alternatives -> TcType -- Type of whole case expressions - -> TcM s (TcType, -- Inferred type of the scrutinee + -> TcM (TcType, -- Inferred type of the scrutinee [TcMatch], -- Translated alternatives LIE) tcMatchesCase matches expr_ty - = newTyVarTy_OpenKind `thenNF_Tc` \ scrut_ty -> - tcMatches [] matches (mkFunTy scrut_ty expr_ty) CaseAlt `thenTc` \ (matches', lie) -> + = newTyVarTy openTypeKind `thenNF_Tc` \ scrut_ty -> + tcMatches [] CaseAlt matches (mkFunTy scrut_ty expr_ty) `thenTc` \ (matches', lie) -> returnTc (scrut_ty, matches', lie) -tcMatchLambda :: RenamedMatch -> TcType -> TcM s (TcMatch, LIE) -tcMatchLambda match res_ty = tcMatch [] match res_ty LambdaBody +tcMatchLambda :: RenamedMatch -> TcType -> TcM (TcMatch, LIE) +tcMatchLambda match res_ty = tcMatch [] LambdaExpr match res_ty \end{code} \begin{code} tcMatches :: [(Name,Id)] + -> RenamedMatchContext -> [RenamedMatch] -> TcType - -> StmtCtxt - -> TcM s ([TcMatch], LIE) + -> TcM ([TcMatch], LIE) -tcMatches xve matches expected_ty fun_or_case +tcMatches xve fun_or_case matches expected_ty = mapAndUnzipTc tc_match matches `thenTc` \ (matches, lies) -> returnTc (matches, plusLIEs lies) where - tc_match match = tcMatch xve match expected_ty fun_or_case + tc_match match = tcMatch xve fun_or_case match expected_ty \end{code} @@ -121,114 +126,66 @@ tcMatches xve matches expected_ty fun_or_case \begin{code} tcMatch :: [(Name,Id)] + -> RenamedMatchContext -> RenamedMatch -> TcType -- Expected result-type of the Match. -- Early unification with this guy gives better error messages - -> StmtCtxt - -> TcM s (TcMatch, LIE) - -tcMatch xve1 match@(Match sig_tvs pats maybe_rhs_sig grhss) expected_ty ctxt - = tcAddSrcLoc (getMatchLoc match) $ - tcAddErrCtxt (matchCtxt ctxt match) $ - - if null sig_tvs then -- The common case - tc_match expected_ty `thenTc` \ (_, match_and_lie) -> - returnTc match_and_lie + -> TcM (TcMatch, LIE) - else - -- If there are sig tvs we must be careful *not* to use - -- expected_ty right away, else we'll unify with tyvars free - -- in the envt. So invent a fresh tyvar and use that instead - newTyVarTy_OpenKind `thenNF_Tc` \ tyvar_ty -> +tcMatch xve1 ctxt match@(Match sig_tvs pats maybe_rhs_sig grhss) expected_ty + = tcAddSrcLoc (getMatchLoc match) $ -- At one stage I removed this; + tcAddErrCtxt (matchCtxt ctxt match) $ -- I'm not sure why, so I put it back + + tcMatchPats pats expected_ty tc_grhss `thenTc` \ ((pats', grhss'), lie, ex_binds) -> + returnTc (Match [] pats' Nothing (glue_on Recursive ex_binds grhss'), lie) - -- Extend the tyvar env and check the match itself - mapNF_Tc tcHsTyVar sig_tvs `thenNF_Tc` \ sig_tyvars -> - tcExtendTyVarEnv sig_tyvars ( - tc_match tyvar_ty - ) `thenTc` \ (pat_ids, match_and_lie) -> + where + tc_grhss pats' rhs_ty + = -- Check that the remaining "expected type" is not a rank-2 type + -- If it is it'll mess up the unifier when checking the RHS + checkTc (isTauTy rhs_ty) lurkingRank2SigErr `thenTc_` - -- Check that the scoped type variables from the patterns - -- have not been constrained - tcAddErrCtxtM (sigPatCtxt sig_tyvars pat_ids) ( - checkSigTyVars sig_tyvars - ) `thenTc_` + -- Deal with the result signature + tc_result_sig maybe_rhs_sig ( - -- *Now* we're free to unify with expected_ty - unifyTauTy expected_ty tyvar_ty `thenTc_` + -- Typecheck the body + tcExtendLocalValEnv xve1 $ + tcGRHSs ctxt grhss rhs_ty `thenTc` \ (grhss', lie) -> + returnTc ((pats', grhss'), lie) + ) - returnTc match_and_lie + tc_result_sig Nothing thing_inside + = thing_inside + tc_result_sig (Just sig) thing_inside + = tcAddScopedTyVars [sig] $ + tcHsSigType sig `thenTc` \ sig_ty -> - where - tc_match expected_ty -- Any sig tyvars are in scope by now - = -- STEP 1: Typecheck the patterns - tcMatchPats pats expected_ty `thenTc` \ (rhs_ty, pats', lie_req1, ex_tvs, pat_bndrs, lie_avail) -> - let - xve2 = bagToList pat_bndrs - pat_ids = map snd xve2 - ex_tv_list = bagToList ex_tvs - in - - -- STEP 2: Check that the remaining "expected type" is not a rank-2 type - -- If it is it'll mess up the unifier when checking the RHS - checkTc (isTauTy rhs_ty) lurkingRank2SigErr `thenTc_` - - -- STEP 3: Unify with the rhs type signature if any - (case maybe_rhs_sig of - Nothing -> returnTc () - Just sig -> tcHsType sig `thenTc` \ sig_ty -> - - -- Check that the signature isn't a polymorphic one, which - -- we don't permit (at present, anyway) - checkTc (isTauTy sig_ty) (polyPatSig sig_ty) `thenTc_` - unifyTauTy rhs_ty sig_ty - ) `thenTc_` - - -- STEP 4: Typecheck the guarded RHSs and the associated where clause - tcExtendLocalValEnv xve1 (tcExtendLocalValEnv xve2 ( - tcGRHSs grhss rhs_ty ctxt - )) `thenTc` \ (grhss', lie_req2) -> - - -- STEP 5: Check for existentially bound type variables - tcExtendGlobalTyVars (tyVarsOfType rhs_ty) ( - tcAddErrCtxtM (sigPatCtxt ex_tv_list pat_ids) $ - checkSigTyVars ex_tv_list `thenTc` \ zonked_ex_tvs -> - tcSimplifyAndCheck - (text ("the existential context of a data constructor")) - (mkVarSet zonked_ex_tvs) - lie_avail (lie_req1 `plusLIE` lie_req2) - ) `thenTc` \ (lie_req', ex_binds) -> - - -- STEP 6 In case there are any polymorpic, overloaded binders in the pattern - -- (which can happen in the case of rank-2 type signatures, or data constructors - -- with polymorphic arguments), we must do a bindInstsOfLocalFns here - bindInstsOfLocalFuns lie_req' pat_ids `thenTc` \ (lie_req'', inst_binds) -> + -- Check that the signature isn't a polymorphic one, which + -- we don't permit (at present, anyway) + checkTc (isTauTy sig_ty) (polyPatSig sig_ty) `thenTc_` + unifyTauTy expected_ty sig_ty `thenTc_` + thing_inside - -- Phew! All done. - let - grhss'' = glue_on Recursive ex_binds $ - glue_on Recursive inst_binds grhss' - in - returnTc (pat_ids, (Match [] pats' Nothing grhss'', lie_req'')) -- glue_on just avoids stupid dross glue_on _ EmptyMonoBinds grhss = grhss -- The common case glue_on is_rec mbinds (GRHSs grhss binds ty) = GRHSs grhss (mkMonoBind mbinds [] is_rec `ThenBinds` binds) ty -tcGRHSs :: RenamedGRHSs - -> TcType -> StmtCtxt - -> TcM s (TcGRHSs, LIE) +tcGRHSs :: RenamedMatchContext -> RenamedGRHSs + -> TcType + -> TcM (TcGRHSs, LIE) -tcGRHSs (GRHSs grhss binds _) expected_ty ctxt +tcGRHSs ctxt (GRHSs grhss binds _) expected_ty = tcBindsAndThen glue_on binds (tc_grhss grhss) where tc_grhss grhss - = mapAndUnzipTc tc_grhs grhss `thenTc` \ (grhss', lies) -> + = mapAndUnzipTc tc_grhs grhss `thenTc` \ (grhss', lies) -> returnTc (GRHSs grhss' EmptyBinds (Just expected_ty), plusLIEs lies) tc_grhs (GRHS guarded locn) - = tcAddSrcLoc locn $ - tcStmts ctxt (\ty -> ty) guarded expected_ty `thenTc` \ (guarded', lie) -> + = tcAddSrcLoc locn $ + tcStmts ctxt (\ty -> ty, expected_ty) guarded `thenTc` \ (guarded', lie) -> returnTc (GRHS guarded' locn, lie) \end{code} @@ -239,14 +196,103 @@ tcGRHSs (GRHSs grhss binds _) expected_ty ctxt %* * %************************************************************************ -\begin{code} -tcMatchPats [] expected_ty +\begin{code} +tcMatchPats + :: [RenamedPat] -> TcType + -> ([TypecheckedPat] -> TcType -> TcM (a, LIE)) + -> TcM (a, LIE, TcDictBinds) +-- 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 expected_ty thing_inside + = -- STEP 1: Bring pattern-signature type variables into scope + tcAddScopedTyVars (collectSigTysFromPats pats) $ + + -- STEP 2: Typecheck the patterns themselves, gathering all the stuff + tc_match_pats pats expected_ty `thenTc` \ (rhs_ty, pats', lie_req1, ex_tvs, pat_bndrs, lie_avail) -> + + -- STEP 3: Extend the environment, and do the thing inside + let + xve = bagToList pat_bndrs + pat_ids = map snd xve + in + tcExtendLocalValEnv xve (thing_inside pats' rhs_ty) `thenTc` \ (result, lie_req2) -> + + -- STEP 4: Check for existentially bound type variables + -- I'm a bit concerned that lie_req1 from an 'inner' pattern in the list + -- might need (via lie_req2) something made available from an 'outer' + -- pattern. But it's inconvenient to deal with, and I can't find an example + tcCheckExistentialPat pat_ids ex_tvs lie_avail lie_req2 rhs_ty `thenTc` \ (lie_req2', ex_binds) -> + + returnTc (result, lie_req1 `plusLIE` lie_req2', ex_binds) + +tcAddScopedTyVars :: [RenamedHsType] -> TcM a -> TcM a +-- Find the not-already-in-scope signature type variables, +-- kind-check them, and bring them into scope +-- +-- We no longer specify that these type variables must be univerally +-- quantified (lots of email on the subject). If you want to put that +-- back in, you need to +-- a) Do a checkSigTyVars after thing_inside +-- b) More insidiously, don't pass in expected_ty, else +-- we unify with it too early and checkSigTyVars barfs +-- Instead you have to pass in a fresh ty var, and unify +-- it with expected_ty afterwards +tcAddScopedTyVars sig_tys thing_inside + = tcGetEnv `thenNF_Tc` \ env -> + let + all_sig_tvs = foldr (unionNameSets . extractHsTyVars) emptyNameSet sig_tys + sig_tvs = filter not_in_scope (nameSetToList all_sig_tvs) + not_in_scope tv = not (tcInLocalScope env tv) + in + tcScopedTyVars sig_tvs (kcHsSigTypes sig_tys) thing_inside + +tcCheckExistentialPat :: [TcId] -- Ids bound by this pattern + -> Bag TcTyVar -- Existentially quantified tyvars bound by pattern + -> LIE -- and context + -> LIE -- Required context + -> TcType -- and result type; vars in here must not escape + -> TcM (LIE, TcDictBinds) -- LIE to float out and dict bindings +tcCheckExistentialPat ids ex_tvs lie_avail lie_req result_ty + | isEmptyBag ex_tvs && all not_overloaded ids + -- Short cut for case when there are no existentials + -- and no polymorphic overloaded variables + -- e.g. f :: (forall a. Ord a => a -> a) -> Int -> Int + -- f op x = .... + -- Here we must discharge op Methods + = ASSERT( isEmptyLIE lie_avail ) + returnTc (lie_req, EmptyMonoBinds) + + | otherwise + = tcExtendGlobalTyVars (tyVarsOfType result_ty) $ + tcAddErrCtxtM (sigPatCtxt tv_list ids) $ + + -- In case there are any polymorpic, overloaded binders in the pattern + -- (which can happen in the case of rank-2 type signatures, or data constructors + -- with polymorphic arguments), we must do a bindInstsOfLocalFns here + bindInstsOfLocalFuns lie_req ids `thenTc` \ (lie1, inst_binds) -> + + -- Deal with overloaded functions bound by the pattern + tcSimplifyCheck doc tv_list + (lieToList lie_avail) lie1 `thenTc` \ (lie2, dict_binds) -> + checkSigTyVars tv_list emptyVarSet `thenTc_` + + returnTc (lie2, dict_binds `AndMonoBinds` inst_binds) + where + doc = text ("the existential context of a data constructor") + tv_list = bagToList ex_tvs + not_overloaded id = case splitSigmaTy (idType id) of + (_, theta, _) -> null theta + +tc_match_pats [] expected_ty = returnTc (expected_ty, [], emptyLIE, emptyBag, emptyBag, emptyLIE) -tcMatchPats (pat:pats) expected_ty +tc_match_pats (pat:pats) expected_ty = unifyFunTy expected_ty `thenTc` \ (arg_ty, rest_ty) -> - tcPat tcPatBndr_NoSigs pat arg_ty `thenTc` \ (pat', lie_req, pat_tvs, pat_ids, lie_avail) -> - tcMatchPats pats rest_ty `thenTc` \ (rhs_ty, pats', lie_reqs, pats_tvs, pats_ids, lie_avails) -> + tcPat tcMonoPatBndr pat arg_ty `thenTc` \ (pat', lie_req, pat_tvs, pat_ids, lie_avail) -> + tc_match_pats pats rest_ty `thenTc` \ (rhs_ty, pats', lie_reqs, pats_tvs, pats_ids, lie_avails) -> returnTc ( rhs_ty, pat':pats', lie_req `plusLIE` lie_reqs, @@ -263,99 +309,127 @@ tcMatchPats (pat:pats) expected_ty %* * %************************************************************************ +Typechecking statements is rendered a bit tricky by parallel list comprehensions: -\begin{code} -tcStmts :: StmtCtxt - -> (TcType -> TcType) -- m, the relationship type of pat and rhs in pat <- rhs - -> [RenamedStmt] - -> TcType -- elt_ty, where type of the comprehension is (m elt_ty) - -> TcM s ([TcStmt], LIE) - -tcStmts do_or_lc m (stmt@(ReturnStmt exp) : stmts) elt_ty - = ASSERT( null stmts ) - tcSetErrCtxt (stmtCtxt do_or_lc stmt) $ - tcExpr exp elt_ty `thenTc` \ (exp', exp_lie) -> - returnTc ([ReturnStmt exp'], exp_lie) - - -- ExprStmt at the end -tcStmts do_or_lc m [stmt@(ExprStmt exp src_loc)] elt_ty - = tcSetErrCtxt (stmtCtxt do_or_lc stmt) $ - tcExpr exp (m elt_ty) `thenTc` \ (exp', exp_lie) -> - returnTc ([ExprStmt exp' src_loc], exp_lie) - - -- ExprStmt not at the end -tcStmts do_or_lc m (stmt@(ExprStmt exp src_loc) : stmts) elt_ty - = ASSERT( isDoStmt do_or_lc ) - tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt do_or_lc stmt) $ - -- exp has type (m tau) for some tau (doesn't matter what) - newTyVarTy_OpenKind `thenNF_Tc` \ any_ty -> - tcExpr exp (m any_ty) - ) `thenTc` \ (exp', exp_lie) -> - tcStmts do_or_lc m stmts elt_ty `thenTc` \ (stmts', stmts_lie) -> - returnTc (ExprStmt exp' src_loc : stmts', - exp_lie `plusLIE` stmts_lie) - -tcStmts do_or_lc m (stmt@(GuardStmt exp src_loc) : stmts) elt_ty - = ASSERT( not (isDoStmt do_or_lc) ) - tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( - tcAddSrcLoc src_loc $ - tcExpr exp boolTy - ) `thenTc` \ (exp', exp_lie) -> - tcStmts do_or_lc m stmts elt_ty `thenTc` \ (stmts', stmts_lie) -> - returnTc (GuardStmt exp' src_loc : stmts', - exp_lie `plusLIE` stmts_lie) - -tcStmts do_or_lc m (stmt@(BindStmt pat exp src_loc) : stmts) elt_ty - = tcAddSrcLoc src_loc ( - tcSetErrCtxt (stmtCtxt do_or_lc stmt) $ - newTyVarTy boxedTypeKind `thenNF_Tc` \ pat_ty -> - tcPat tcPatBndr_NoSigs pat pat_ty `thenTc` \ (pat', pat_lie, pat_tvs, pat_ids, avail) -> - tcExpr exp (m pat_ty) `thenTc` \ (exp', exp_lie) -> - returnTc (pat', exp', - pat_lie `plusLIE` exp_lie, - pat_tvs, pat_ids, avail) - ) `thenTc` \ (pat', exp', lie_req, pat_tvs, pat_bndrs, lie_avail) -> - let - new_val_env = bagToList pat_bndrs - pat_ids = map snd new_val_env - pat_tv_list = bagToList pat_tvs - in + [ (g x, h x) | ... ; let g v = ... + | ... ; let h v = ... ] - -- Do the rest; we don't need to add the pat_tvs to the envt - -- because they all appear in the pat_ids's types - tcExtendLocalValEnv new_val_env ( - tcStmts do_or_lc m stmts elt_ty - ) `thenTc` \ (stmts', stmts_lie) -> +It's possible that g,h are overloaded, so we need to feed the LIE from the +(g x, h x) up through both lots of bindings (so we get the bindInstsOfLocalFuns). +Similarly if we had an existential pattern match: + data T = forall a. Show a => C a - -- Reinstate context for existential checks - tcSetErrCtxt (stmtCtxt do_or_lc stmt) $ - tcExtendGlobalTyVars (tyVarsOfType (m elt_ty)) $ - tcAddErrCtxtM (sigPatCtxt pat_tv_list pat_ids) $ + [ (show x, show y) | ... ; C x <- ... + | ... ; C y <- ... ] - checkSigTyVars pat_tv_list `thenTc` \ zonked_pat_tvs -> +Then we need the LIE from (show x, show y) to be simplified against +the bindings for x and y. - tcSimplifyAndCheck - (text ("the existential context of a data constructor")) - (mkVarSet zonked_pat_tvs) - lie_avail stmts_lie `thenTc` \ (final_lie, dict_binds) -> +It's difficult to do this in parallel, so we rely on the renamer to +ensure that g,h and x,y don't duplicate, and simply grow the environment. +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. - returnTc (BindStmt pat' exp' src_loc : - consLetStmt (mkMonoBind dict_binds [] Recursive) stmts', - lie_req `plusLIE` final_lie) +\begin{code} +tcStmts do_or_lc m_ty stmts + = tcStmtsAndThen (:) do_or_lc m_ty stmts (returnTc ([], emptyLIE)) + +tcStmtsAndThen + :: (TcStmt -> thing -> thing) -- Combiner + -> RenamedMatchContext + -> (TcType -> TcType, TcType) -- m, the relationship type of pat and rhs in pat <- rhs + -- elt_ty, where type of the comprehension is (m elt_ty) + -> [RenamedStmt] + -> TcM (thing, LIE) + -> TcM (thing, LIE) -tcStmts do_or_lc m (LetStmt binds : stmts) elt_ty - = tcBindsAndThen -- No error context, but a binding group is - combine -- rather a large thing for an error context anyway - binds - (tcStmts do_or_lc m stmts elt_ty) - where - combine is_rec binds' stmts' = consLetStmt (mkMonoBind binds' [] is_rec) stmts' + -- Base case +tcStmtsAndThen combine do_or_lc m_ty [] do_next + = do_next +tcStmtsAndThen combine do_or_lc m_ty (stmt:stmts) do_next + = tcStmtAndThen combine do_or_lc m_ty stmt + (tcStmtsAndThen combine do_or_lc m_ty stmts do_next) -isDoStmt DoStmt = True -isDoStmt other = False + -- LetStmt +tcStmtAndThen combine do_or_lc m_ty (LetStmt binds) thing_inside + = tcBindsAndThen -- No error context, but a binding group is + (glue_binds combine) -- rather a large thing for an error context anyway + binds + thing_inside + +tcStmtAndThen combine do_or_lc m_ty@(m,elt_ty) stmt@(BindStmt pat exp src_loc) thing_inside + = tcAddSrcLoc src_loc $ + tcAddErrCtxt (stmtCtxt do_or_lc stmt) $ + newTyVarTy liftedTypeKind `thenNF_Tc` \ pat_ty -> + tcExpr exp (m pat_ty) `thenTc` \ (exp', exp_lie) -> + tcMatchPats [pat] (mkFunTy pat_ty (m elt_ty)) (\ [pat'] _ -> + tcPopErrCtxt $ + thing_inside `thenTc` \ (thing, lie) -> + returnTc ((BindStmt pat' exp' src_loc, thing), lie) + ) `thenTc` \ ((stmt', thing), lie, dict_binds) -> + returnTc (combine stmt' (glue_binds combine Recursive dict_binds thing), + lie `plusLIE` exp_lie) + + + -- ParStmt +tcStmtAndThen combine do_or_lc m_ty (ParStmtOut bndr_stmts_s) thing_inside + = loop bndr_stmts_s `thenTc` \ ((pairs', thing), lie) -> + returnTc (combine (ParStmtOut pairs') thing, lie) + where + loop [] + = thing_inside `thenTc` \ (thing, stmts_lie) -> + returnTc (([], thing), stmts_lie) + + loop ((bndrs,stmts) : pairs) + = tcStmtsAndThen + combine_par (DoCtxt ListComp) m_ty stmts + -- Notice we pass on m_ty; the result type is used only + -- to get escaping type variables for checkExistentialPat + (tcLookupLocalIds bndrs `thenNF_Tc` \ bndrs' -> + loop pairs `thenTc` \ ((pairs', thing), lie) -> + returnTc (([], (bndrs', pairs', thing)), lie)) `thenTc` \ ((stmts', (bndrs', pairs', thing)), lie) -> + + returnTc ( ((bndrs',stmts') : pairs', thing), lie) + + combine_par stmt (stmts, thing) = (stmt:stmts, thing) + + -- ExprStmt +tcStmtAndThen combine do_or_lc m_ty@(m, res_elt_ty) stmt@(ExprStmt exp locn) thing_inside + = tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( + if isDoExpr do_or_lc then + newTyVarTy openTypeKind `thenNF_Tc` \ any_ty -> + tcExpr exp (m any_ty) + else + tcExpr exp boolTy + ) `thenTc` \ (exp', stmt_lie) -> + + thing_inside `thenTc` \ (thing, stmts_lie) -> + + returnTc (combine (ExprStmt exp' locn) thing, + stmt_lie `plusLIE` stmts_lie) + + + -- Result statements +tcStmtAndThen combine do_or_lc m_ty@(m, res_elt_ty) stmt@(ResultStmt exp locn) thing_inside + = tcSetErrCtxt (stmtCtxt do_or_lc stmt) ( + if isDoExpr do_or_lc then + tcExpr exp (m res_elt_ty) + else + tcExpr exp res_elt_ty + ) `thenTc` \ (exp', stmt_lie) -> + + thing_inside `thenTc` \ (thing, stmts_lie) -> + + returnTc (combine (ResultStmt exp' locn) thing, + stmt_lie `plusLIE` stmts_lie) + + +------------------------------ +glue_binds combine is_rec binds thing + | nullMonoBinds binds = thing + | otherwise = combine (LetStmt (mkMonoBind binds [] is_rec)) thing \end{code} @@ -377,39 +451,12 @@ sameNoOfArgs matches = length (nub (map args_in_match matches)) == 1 \end{code} \begin{code} -matchCtxt CaseAlt match - = hang (ptext SLIT("In a case alternative:")) - 4 (pprMatch (True,empty) {-is_case-} match) - -matchCtxt (FunRhs fun) match - = hang (hcat [ptext SLIT("In an equation for function "), quotes (ppr_fun), char ':']) - 4 (pprMatch (False, ppr_fun) {-not case-} match) - where - ppr_fun = ppr fun - -matchCtxt LambdaBody match - = hang (ptext SLIT("In the lambda expression")) - 4 (pprMatch (True, empty) match) +matchCtxt ctxt match = hang (pprMatchContext ctxt <> colon) 4 (pprMatch ctxt match) +stmtCtxt do_or_lc stmt = hang (pprMatchContext do_or_lc <> colon) 4 (ppr stmt) varyingArgsErr name matches = sep [ptext SLIT("Varying number of arguments for function"), quotes (ppr name)] lurkingRank2SigErr = ptext SLIT("Too few explicit arguments when defining a function with a rank-2 type") - -stmtCtxt do_or_lc stmt - = hang (ptext SLIT("In") <+> what <> colon) - 4 (ppr stmt) - where - what = case do_or_lc of - ListComp -> ptext SLIT("a list-comprehension qualifier") - DoStmt -> ptext SLIT("a do statement") - PatBindRhs -> thing <+> ptext SLIT("a pattern binding") - FunRhs f -> thing <+> ptext SLIT("an equation for") <+> quotes (ppr f) - CaseAlt -> thing <+> ptext SLIT("a case alternative") - LambdaBody -> thing <+> ptext SLIT("a lambda abstraction") - thing = case stmt of - BindStmt _ _ _ -> ptext SLIT("a pattern guard for") - GuardStmt _ _ -> ptext SLIT("a guard for") - ExprStmt _ _ -> ptext SLIT("the right-hand side of") \end{code}