X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsExpr.lhs;h=f9d0a6c021d66cebf434e78bcb0e7a6cf3bbfa06;hb=16e4ce4c0c02650082f2e11982017c903c549ad5;hp=6e2efa07885d70a15a91c22379a3e99e3910c602;hpb=1bba522f5ec82c43abd2ba4e84127b9c915dd020;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsExpr.lhs b/ghc/compiler/deSugar/DsExpr.lhs index 6e2efa0..f9d0a6c 100644 --- a/ghc/compiler/deSugar/DsExpr.lhs +++ b/ghc/compiler/deSugar/DsExpr.lhs @@ -4,51 +4,65 @@ \section[DsExpr]{Matching expressions (Exprs)} \begin{code} -module DsExpr ( dsExpr, dsLet ) where +module DsExpr ( dsExpr, dsLet, dsLit ) where #include "HsVersions.h" -import HsSyn ( failureFreePat, - HsExpr(..), OutPat(..), HsLit(..), ArithSeqInfo(..), - Stmt(..), StmtCtxt(..), Match(..), HsBinds(..), MonoBinds(..), - mkSimpleMatch - ) -import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, - TypecheckedStmt - ) -import CoreSyn -import CoreUtils ( exprType, mkIfThenElse, bindNonRec ) - -import DsMonad +import Match ( matchWrapper, matchSimply ) +import MatchLit ( dsLit ) import DsBinds ( dsMonoBinds, AutoScc(..) ) import DsGRHSs ( dsGuarded ) -import DsCCall ( dsCCall, resultWrapper ) -import DsListComp ( dsListComp ) -import DsUtils ( mkErrorAppDs, mkDsLets, mkStringLit, mkStringLitFS, - mkConsExpr, mkNilExpr, mkIntegerLit +import DsCCall ( dsCCall ) +import DsListComp ( dsListComp, dsPArrComp ) +import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr, + mkCoreTupTy, selectMatchVar, + dsReboundNames, lookupReboundName ) +import DsArrows ( dsProcExpr ) +import DsMonad + +#ifdef GHCI + -- Template Haskell stuff iff bootstrapped +import DsMeta ( dsBracket, dsReify ) +#endif + +import HsSyn ( HsExpr(..), Pat(..), ArithSeqInfo(..), + Stmt(..), HsMatchContext(..), HsStmtContext(..), + Match(..), HsBinds(..), MonoBinds(..), HsConDetails(..), + ReboundNames, + mkSimpleMatch, isDoExpr ) -import Match ( matchWrapper, matchSimply ) +import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, hsPatType ) +-- NB: The desugarer, which straddles the source and Core worlds, sometimes +-- needs to see source types (newtypes etc), and sometimes not +-- So WATCH OUT; check each use of split*Ty functions. +-- Sigh. This is a pain. + +import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppArgs, + tcSplitTyConApp, isUnLiftedType, Type, + mkAppTy ) +import Type ( splitFunTys ) +import CoreSyn +import CoreUtils ( exprType, mkIfThenElse, bindNonRec ) + +import FieldLabel ( FieldLabel, fieldLabelTyCon ) import CostCentre ( mkUserCC ) -import Id ( Id, idType, recordSelectorFieldLabel ) +import Id ( Id, idType, idName, recordSelectorFieldLabel ) import PrelInfo ( rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID ) -import DataCon ( DataCon, dataConWrapId, dataConArgTys, dataConFieldLabels ) +import DataCon ( DataCon, dataConWrapId, dataConFieldLabels, dataConInstOrigArgTys ) import DataCon ( isExistentialDataCon ) -import Literal ( Literal(..) ) -import Type ( splitFunTys, - splitAlgTyConApp, splitAlgTyConApp_maybe, splitTyConApp_maybe, - isNotUsgTy, unUsgTy, - splitAppTy, isUnLiftedType, Type - ) -import TysWiredIn ( tupleCon, listTyCon, charDataCon, intDataCon, isIntegerTy ) -import BasicTypes ( RecFlag(..), Boxity(..) ) -import Maybes ( maybeToBool ) -import Unique ( hasKey, ratioTyConKey ) +import Name ( Name ) +import TyCon ( tyConDataCons ) +import TysWiredIn ( tupleCon, mkTupleTy ) +import BasicTypes ( RecFlag(..), Boxity(..), ipNameName ) +import PrelNames ( toPName, + returnMName, bindMName, thenMName, failMName, + mfixName ) +import SrcLoc ( noSrcLoc ) import Util ( zipEqual, zipWithEqual ) import Outputable - -import Ratio ( numerator, denominator ) +import FastString \end{code} @@ -79,32 +93,64 @@ dsLet (ThenBinds b1 b2) body = dsLet b2 body `thenDs` \ body' -> dsLet b1 body' +dsLet (IPBinds binds is_with) body + = foldlDs dsIPBind body binds + where + dsIPBind body (n, e) + = dsExpr e `thenDs` \ e' -> + returnDs (Let (NonRec (ipNameName n) e') body) + -- Special case for bindings which bind unlifted variables +-- We need to do a case right away, rather than building +-- a tuple and doing selections. -- Silently ignore INLINE pragmas... -dsLet (MonoBind (AbsBinds [] [] binder_triples inlines - (PatMonoBind pat grhss loc)) sigs is_rec) body - | or [isUnLiftedType (idType g) | (_, g, l) <- binder_triples] +dsLet bind@(MonoBind (AbsBinds [] [] exports inlines binds) sigs is_rec) body + | or [isUnLiftedType (idType g) | (_, g, l) <- exports] = ASSERT (case is_rec of {NonRecursive -> True; other -> False}) - putSrcLocDs loc $ - dsGuarded grhss `thenDs` \ rhs -> - let - body' = foldr bind body binder_triples - bind (tyvars, g, l) body = ASSERT( null tyvars ) - bindNonRec g (Var l) body - in - mkErrorAppDs iRREFUT_PAT_ERROR_ID result_ty (showSDoc (ppr pat)) - `thenDs` \ error_expr -> - matchSimply rhs PatBindMatch pat body' error_expr + -- Unlifted bindings are always non-recursive + -- and are always a Fun or Pat monobind + -- + -- ToDo: in some bizarre case it's conceivable that there + -- could be dict binds in the 'binds'. (See the notes + -- below. Then pattern-match would fail. Urk.) + case binds of + FunMonoBind fun _ matches loc + -> putSrcLocDs loc $ + matchWrapper (FunRhs (idName fun)) matches `thenDs` \ (args, rhs) -> + ASSERT( null args ) -- Functions aren't lifted + returnDs (bindNonRec fun rhs body_w_exports) + + PatMonoBind pat grhss loc + -> putSrcLocDs loc $ + dsGuarded grhss `thenDs` \ rhs -> + mk_error_app pat `thenDs` \ error_expr -> + matchSimply rhs PatBindRhs pat body_w_exports error_expr + + other -> pprPanic "dsLet: unlifted" (ppr bind $$ ppr body) where - result_ty = exprType body + body_w_exports = foldr bind_export body exports + bind_export (tvs, g, l) body = ASSERT( null tvs ) + bindNonRec g (Var l) body + + mk_error_app pat = mkErrorAppDs iRREFUT_PAT_ERROR_ID + (exprType body) + (showSDoc (ppr pat)) -- Ordinary case for bindings dsLet (MonoBind binds sigs is_rec) body = dsMonoBinds NoSccs binds [] `thenDs` \ prs -> - case is_rec of - Recursive -> returnDs (Let (Rec prs) body) - NonRecursive -> returnDs (mkDsLets [NonRec b r | (b,r) <- prs] body) -\end{code} + returnDs (Let (Rec prs) body) + -- Use a Rec regardless of is_rec. + -- Why? Because it allows the MonoBinds to be all + -- mixed up, which is what happens in one rare case + -- Namely, for an AbsBind with no tyvars and no dicts, + -- but which does have dictionary bindings. + -- See notes with TcSimplify.inferLoop [NO TYVARS] + -- It turned out that wrapping a Rec here was the easiest solution + -- + -- NB The previous case dealt with unlifted bindings, so we + -- only have to deal with lifted ones now; so Rec is ok +\end{code} %************************************************************************ %* * @@ -115,20 +161,20 @@ dsLet (MonoBind binds sigs is_rec) body \begin{code} dsExpr :: TypecheckedHsExpr -> DsM CoreExpr -dsExpr (HsVar var) = returnDs (Var var) -dsExpr (HsIPVar var) = returnDs (Var var) -dsExpr (HsLit lit) = dsLit lit +dsExpr (HsPar x) = dsExpr x +dsExpr (HsVar var) = returnDs (Var var) +dsExpr (HsIPVar ip) = returnDs (Var (ipNameName ip)) +dsExpr (HsLit lit) = dsLit lit -- HsOverLit has been gotten rid of by the type checker dsExpr expr@(HsLam a_Match) - = matchWrapper LambdaMatch [a_Match] "lambda" `thenDs` \ (binders, matching_code) -> + = matchWrapper LambdaExpr [a_Match] `thenDs` \ (binders, matching_code) -> returnDs (mkLams binders matching_code) dsExpr expr@(HsApp fun arg) = dsExpr fun `thenDs` \ core_fun -> dsExpr arg `thenDs` \ core_arg -> returnDs (core_fun `App` core_arg) - \end{code} Operator sections. At first it looks as if we can convert @@ -165,6 +211,8 @@ dsExpr (SectionL expr op) -- for the type of y, we need the type of op's 2nd argument let (x_ty:y_ty:_, _) = splitFunTys (exprType core_op) + -- Must look through an implicit-parameter type; + -- newtype impossible; hence Type.splitFunTys in dsExpr expr `thenDs` \ x_core -> newSysLocalDs x_ty `thenDs` \ x_id -> @@ -179,6 +227,7 @@ dsExpr (SectionR op expr) -- for the type of x, we need the type of op's 2nd argument let (x_ty:y_ty:_, _) = splitFunTys (exprType core_op) + -- See comment with SectionL in dsExpr expr `thenDs` \ y_core -> newSysLocalDs x_ty `thenDs` \ x_id -> @@ -197,60 +246,59 @@ dsExpr (HsSCC cc expr) getModuleDs `thenDs` \ mod_name -> returnDs (Note (SCC (mkUserCC cc mod_name)) core_expr) + +-- hdaume: core annotation + +dsExpr (HsCoreAnn fs expr) + = dsExpr expr `thenDs` \ core_expr -> + returnDs (Note (CoreNote $ unpackFS fs) core_expr) + -- special case to handle unboxed tuple patterns. dsExpr (HsCase discrim matches src_loc) | all ubx_tuple_match matches = putSrcLocDs src_loc $ - dsExpr discrim `thenDs` \ core_discrim -> - matchWrapper CaseMatch matches "case" `thenDs` \ ([discrim_var], matching_code) -> + dsExpr discrim `thenDs` \ core_discrim -> + matchWrapper CaseAlt matches `thenDs` \ ([discrim_var], matching_code) -> case matching_code of Case (Var x) bndr alts | x == discrim_var -> returnDs (Case core_discrim bndr alts) _ -> panic ("dsExpr: tuple pattern:\n" ++ showSDoc (ppr matching_code)) where - ubx_tuple_match (Match _ [TuplePat ps Unboxed] _ _) = True + ubx_tuple_match (Match [TuplePat ps Unboxed] _ _) = True ubx_tuple_match _ = False dsExpr (HsCase discrim matches src_loc) = putSrcLocDs src_loc $ - dsExpr discrim `thenDs` \ core_discrim -> - matchWrapper CaseMatch matches "case" `thenDs` \ ([discrim_var], matching_code) -> + dsExpr discrim `thenDs` \ core_discrim -> + matchWrapper CaseAlt matches `thenDs` \ ([discrim_var], matching_code) -> returnDs (bindNonRec discrim_var core_discrim matching_code) dsExpr (HsLet binds body) = dsExpr body `thenDs` \ body' -> dsLet binds body' -dsExpr (HsWith expr binds) - = dsExpr expr `thenDs` \ expr' -> - foldlDs dsIPBind expr' binds - where - dsIPBind body (n, e) - = dsExpr e `thenDs` \ e' -> - returnDs (Let (NonRec n e') body) - -dsExpr (HsDoOut do_or_lc stmts return_id then_id fail_id result_ty src_loc) - | maybeToBool maybe_list_comp +-- We need the `ListComp' form to use `deListComp' (rather than the "do" form) +-- because the interpretation of `stmts' depends on what sort of thing it is. +-- +dsExpr (HsDo ListComp stmts _ result_ty src_loc) = -- Special case for list comprehensions putSrcLocDs src_loc $ dsListComp stmts elt_ty + where + (_, [elt_ty]) = tcSplitTyConApp result_ty - | otherwise +dsExpr (HsDo do_or_lc stmts ids result_ty src_loc) + | isDoExpr do_or_lc = putSrcLocDs src_loc $ - dsDo do_or_lc stmts return_id then_id fail_id result_ty + dsDo do_or_lc stmts ids result_ty + +dsExpr (HsDo PArrComp stmts _ result_ty src_loc) + = -- Special case for array comprehensions + putSrcLocDs src_loc $ + dsPArrComp stmts elt_ty where - maybe_list_comp - = case (do_or_lc, splitTyConApp_maybe result_ty) of - (ListComp, Just (tycon, [elt_ty])) - | tycon == listTyCon - -> Just elt_ty - other -> Nothing - -- We need the ListComp form to use deListComp (rather than the "do" form) - -- because the "return" in a do block is a call to "PrelBase.return", and - -- not a ReturnStmt. Only the ListComp form has ReturnStmts - - Just elt_ty = maybe_list_comp + (_, [elt_ty]) = tcSplitTyConApp result_ty dsExpr (HsIf guard_expr then_expr else_expr src_loc) = putSrcLocDs src_loc $ @@ -279,20 +327,33 @@ dsExpr (TyApp expr tys) \underline{\bf Various data construction things} % ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \begin{code} -dsExpr (ExplicitListOut ty xs) +dsExpr (ExplicitList ty xs) = go xs where go [] = returnDs (mkNilExpr ty) go (x:xs) = dsExpr x `thenDs` \ core_x -> go xs `thenDs` \ core_xs -> - ASSERT( isNotUsgTy ty ) returnDs (mkConsExpr ty core_x core_xs) +-- we create a list from the array elements and convert them into a list using +-- `PrelPArr.toP' +-- +-- * the main disadvantage to this scheme is that `toP' traverses the list +-- twice: once to determine the length and a second time to put to elements +-- into the array; this inefficiency could be avoided by exposing some of +-- the innards of `PrelPArr' to the compiler (ie, have a `PrelPArrBase') so +-- that we can exploit the fact that we already know the length of the array +-- here at compile time +-- +dsExpr (ExplicitPArr ty xs) + = dsLookupGlobalId toPName `thenDs` \toP -> + dsExpr (ExplicitList ty xs) `thenDs` \coreList -> + returnDs (mkApps (Var toP) [Type ty, coreList]) + dsExpr (ExplicitTuple expr_list boxity) = mapDs dsExpr expr_list `thenDs` \ core_exprs -> returnDs (mkConApp (tupleCon boxity (length expr_list)) - (map (Type . unUsgTy . exprType) core_exprs ++ core_exprs)) - -- the above unUsgTy is *required* -- KSW 1999-04-07 + (map (Type . exprType) core_exprs ++ core_exprs)) dsExpr (ArithSeqOut expr (From from)) = dsExpr expr `thenDs` \ expr2 -> @@ -317,6 +378,24 @@ dsExpr (ArithSeqOut expr (FromThenTo from thn two)) dsExpr thn `thenDs` \ thn2 -> dsExpr two `thenDs` \ two2 -> returnDs (mkApps expr2 [from2, thn2, two2]) + +dsExpr (PArrSeqOut expr (FromTo from two)) + = dsExpr expr `thenDs` \ expr2 -> + dsExpr from `thenDs` \ from2 -> + dsExpr two `thenDs` \ two2 -> + returnDs (mkApps expr2 [from2, two2]) + +dsExpr (PArrSeqOut expr (FromThenTo from thn two)) + = dsExpr expr `thenDs` \ expr2 -> + dsExpr from `thenDs` \ from2 -> + dsExpr thn `thenDs` \ thn2 -> + dsExpr two `thenDs` \ two2 -> + returnDs (mkApps expr2 [from2, thn2, two2]) + +dsExpr (PArrSeqOut expr _) + = panic "DsExpr.dsExpr: Infinite parallel array!" + -- the parser shouldn't have generated it and the renamer and typechecker + -- shouldn't have let it through \end{code} \noindent @@ -344,10 +423,12 @@ constructor @C@, setting all of @C@'s fields to bottom. dsExpr (RecordConOut data_con con_expr rbinds) = dsExpr con_expr `thenDs` \ con_expr' -> let - (arg_tys, _) = splitFunTys (exprType con_expr') + (arg_tys, _) = tcSplitFunTys (exprType con_expr') + -- A newtype in the corner should be opaque; + -- hence TcType.tcSplitFunTys mk_arg (arg_ty, lbl) - = case [rhs | (sel_id,rhs,_) <- rbinds, + = case [rhs | (sel_id,rhs) <- rbinds, lbl == recordSelectorFieldLabel sel_id] of (rhs:rhss) -> ASSERT( null rhss ) dsExpr rhs @@ -387,60 +468,71 @@ might do some argument-evaluation first; and may have to throw away some dictionaries. \begin{code} -dsExpr (RecordUpdOut record_expr record_out_ty dicts rbinds) - = getSrcLocDs `thenDs` \ src_loc -> +dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty []) + = dsExpr record_expr + +dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) + = getSrcLocDs `thenDs` \ src_loc -> dsExpr record_expr `thenDs` \ record_expr' -> -- Desugar the rbinds, and generate let-bindings if -- necessary so that we don't lose sharing let - record_in_ty = exprType record_expr' - (_, in_inst_tys, cons) = splitAlgTyConApp record_in_ty - (_, out_inst_tys, _) = splitAlgTyConApp record_out_ty - cons_to_upd = filter has_all_fields cons + in_inst_tys = tcTyConAppArgs record_in_ty -- Newtype opaque + out_inst_tys = tcTyConAppArgs record_out_ty -- Newtype opaque mk_val_arg field old_arg_id - = case [rhs | (sel_id, rhs, _) <- rbinds, + = case [rhs | (sel_id, rhs) <- rbinds, field == recordSelectorFieldLabel sel_id] of (rhs:rest) -> ASSERT(null rest) rhs [] -> HsVar old_arg_id mk_alt con - = newSysLocalsDs (dataConArgTys con in_inst_tys) `thenDs` \ arg_ids -> + = newSysLocalsDs (dataConInstOrigArgTys con in_inst_tys) `thenDs` \ arg_ids -> -- This call to dataConArgTys won't work for existentials let val_args = zipWithEqual "dsExpr:RecordUpd" mk_val_arg (dataConFieldLabels con) arg_ids - rhs = foldl HsApp (DictApp (TyApp (HsVar (dataConWrapId con)) - out_inst_tys) - dicts) + rhs = foldl HsApp (TyApp (HsVar (dataConWrapId con)) out_inst_tys) val_args in - returnDs (mkSimpleMatch [ConPat con record_in_ty [] [] (map VarPat arg_ids)] + returnDs (mkSimpleMatch [ConPatOut con (PrefixCon (map VarPat arg_ids)) record_in_ty [] []] rhs - (Just record_out_ty) + record_out_ty src_loc) in -- Record stuff doesn't work for existentials - ASSERT( all (not . isExistentialDataCon) cons ) + -- The type checker checks for this, but we need + -- worry only about the constructors that are to be updated + ASSERT2( all (not . isExistentialDataCon) cons_to_upd, ppr expr ) -- It's important to generate the match with matchWrapper, -- and the right hand sides with applications of the wrapper Id -- so that everything works when we are doing fancy unboxing on the -- constructor aguments. - mapDs mk_alt cons_to_upd `thenDs` \ alts -> - matchWrapper RecUpdMatch alts "record update" `thenDs` \ ([discrim_var], matching_code) -> + mapDs mk_alt cons_to_upd `thenDs` \ alts -> + matchWrapper RecUpd alts `thenDs` \ ([discrim_var], matching_code) -> returnDs (bindNonRec discrim_var record_expr' matching_code) where + updated_fields :: [FieldLabel] + updated_fields = [recordSelectorFieldLabel sel_id | (sel_id,_) <- rbinds] + + -- Get the type constructor from the first field label, + -- so that we are sure it'll have all its DataCons + -- (In GHCI, it's possible that some TyCons may not have all + -- their constructors, in a module-loop situation.) + tycon = fieldLabelTyCon (head updated_fields) + data_cons = tyConDataCons tycon + cons_to_upd = filter has_all_fields data_cons + has_all_fields :: DataCon -> Bool has_all_fields con_id - = all ok rbinds + = all (`elem` con_fields) updated_fields where - con_fields = dataConFieldLabels con_id - ok (sel_id, _, _) = recordSelectorFieldLabel sel_id `elem` con_fields + con_fields = dataConFieldLabels con_id \end{code} @@ -462,14 +554,29 @@ dsExpr (DictApp expr dicts) -- becomes a curried application returnDs (foldl (\f d -> f `App` (Var d)) core_expr dicts) \end{code} +Here is where we desugar the Template Haskell brackets and escapes + +\begin{code} +-- Template Haskell stuff + +#ifdef GHCI /* Only if bootstrapping */ +dsExpr (HsBracketOut x ps) = dsBracket x ps +dsExpr (HsReify r) = dsReify r +dsExpr (HsSplice n e _) = pprPanic "dsExpr:splice" (ppr e) +#endif + +-- Arrow notation extension +dsExpr (HsProc pat cmd src_loc) = dsProcExpr pat cmd src_loc +\end{code} + + \begin{code} #ifdef DEBUG -- HsSyn constructs that just shouldn't be here: -dsExpr (HsDo _ _ _) = panic "dsExpr:HsDo" -dsExpr (ExplicitList _) = panic "dsExpr:ExplicitList" dsExpr (ExprWithTySig _ _) = panic "dsExpr:ExprWithTySig" dsExpr (ArithSeqIn _) = panic "dsExpr:ArithSeqIn" +dsExpr (PArrSeqIn _) = panic "dsExpr:PArrSeqIn" #endif \end{code} @@ -479,139 +586,122 @@ dsExpr (ArithSeqIn _) = panic "dsExpr:ArithSeqIn" Basically does the translation given in the Haskell~1.3 report: \begin{code} -dsDo :: StmtCtxt +dsDo :: HsStmtContext Name -> [TypecheckedStmt] - -> Id -- id for: return m - -> Id -- id for: (>>=) m - -> Id -- id for: fail m - -> Type -- Element type; the whole expression has type (m t) + -> ReboundNames Id -- id for: [return,fail,>>=,>>] and possibly mfixName + -> Type -- Element type; the whole expression has type (m t) -> DsM CoreExpr -dsDo do_or_lc stmts return_id then_id fail_id result_ty - = let - (_, b_ty) = splitAppTy result_ty -- result_ty must be of the form (m b) +dsDo do_or_lc stmts ids result_ty + = dsReboundNames ids `thenDs` \ (meth_binds, ds_meths) -> + let + return_id = lookupReboundName ds_meths returnMName + fail_id = lookupReboundName ds_meths failMName + bind_id = lookupReboundName ds_meths bindMName + then_id = lookupReboundName ds_meths thenMName + + (m_ty, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b) + is_do = isDoExpr do_or_lc -- True for both MDo and Do - go [ReturnStmt expr] - = dsExpr expr `thenDs` \ expr2 -> - returnDs (mkApps (Var return_id) [Type b_ty, expr2]) - - go (GuardStmt expr locn : stmts) + -- For ExprStmt, see the comments near HsExpr.Stmt about + -- exactly what ExprStmts mean! + -- + -- In dsDo we can only see DoStmt and ListComp (no guards) + + go [ResultStmt expr locn] + | is_do = do_expr expr locn + | otherwise = do_expr expr locn `thenDs` \ expr2 -> + returnDs (mkApps return_id [Type b_ty, expr2]) + + go (ExprStmt expr a_ty locn : stmts) + | is_do -- Do expression + = do_expr expr locn `thenDs` \ expr2 -> + go stmts `thenDs` \ rest -> + returnDs (mkApps then_id [Type a_ty, Type b_ty, expr2, rest]) + + | otherwise -- List comprehension = do_expr expr locn `thenDs` \ expr2 -> go stmts `thenDs` \ rest -> - let msg = ASSERT( isNotUsgTy b_ty ) - "Pattern match failure in do expression, " ++ showSDoc (ppr locn) - in - mkStringLit msg `thenDs` \ core_msg -> - returnDs (mkIfThenElse expr2 - rest - (App (App (Var fail_id) - (Type b_ty)) - core_msg)) - - go (ExprStmt expr locn : stmts) - = do_expr expr locn `thenDs` \ expr2 -> let - (_, a_ty) = splitAppTy (exprType expr2) -- Must be of form (m a) + msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn) in - if null stmts then - returnDs expr2 - else - go stmts `thenDs` \ rest -> - newSysLocalDs a_ty `thenDs` \ ignored_result_id -> - returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2, - Lam ignored_result_id rest]) + mkStringLit msg `thenDs` \ core_msg -> + returnDs (mkIfThenElse expr2 rest + (App (App fail_id (Type b_ty)) core_msg)) go (LetStmt binds : stmts ) = go stmts `thenDs` \ rest -> dsLet binds rest go (BindStmt pat expr locn : stmts) - = putSrcLocDs locn $ - dsExpr expr `thenDs` \ expr2 -> + = go stmts `thenDs` \ body -> + putSrcLocDs locn $ -- Rest is associated with this location + dsExpr expr `thenDs` \ rhs -> + mkStringLit (mk_msg locn) `thenDs` \ core_msg -> let - (_, a_ty) = splitAppTy (exprType expr2) -- Must be of form (m a) - fail_expr = HsApp (TyApp (HsVar fail_id) [b_ty]) - (HsLit (HsString (_PK_ msg))) - msg = ASSERT2( isNotUsgTy a_ty, ppr a_ty ) - ASSERT2( isNotUsgTy b_ty, ppr b_ty ) - "Pattern match failure in do expression, " ++ showSDoc (ppr locn) - main_match = mkSimpleMatch [pat] - (HsDoOut do_or_lc stmts return_id then_id - fail_id result_ty locn) - (Just result_ty) locn - the_matches - | failureFreePat pat = [main_match] - | otherwise = - [ main_match - , mkSimpleMatch [WildPat a_ty] fail_expr (Just result_ty) locn - ] + -- In a do expression, pattern-match failure just calls + -- the monadic 'fail' rather than throwing an exception + fail_expr = mkApps fail_id [Type b_ty, core_msg] + a_ty = hsPatType pat in - matchWrapper DoBindMatch the_matches match_msg - `thenDs` \ (binders, matching_code) -> - returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2, - mkLams binders matching_code]) + selectMatchVar pat `thenDs` \ var -> + matchSimply (Var var) (StmtCtxt do_or_lc) pat + body fail_expr `thenDs` \ match_code -> + returnDs (mkApps bind_id [Type a_ty, Type b_ty, rhs, Lam var match_code]) + + go (RecStmt rec_stmts later_vars rec_vars rec_rets : stmts) + = go (bind_stmt : stmts) + where + bind_stmt = dsRecStmt m_ty ds_meths rec_stmts later_vars rec_vars rec_rets + in - go stmts + go stmts `thenDs` \ stmts_code -> + returnDs (foldr Let stmts_code meth_binds) where do_expr expr locn = putSrcLocDs locn (dsExpr expr) - - match_msg = case do_or_lc of - DoStmt -> "`do' statement" - ListComp -> "comprehension" + mk_msg locn = "Pattern match failure in do expression at " ++ showSDoc (ppr locn) \end{code} - -%************************************************************************ -%* * -\subsection[DsExpr-literals]{Literals} -%* * -%************************************************************************ - -We give int/float literals type @Integer@ and @Rational@, respectively. -The typechecker will (presumably) have put \tr{from{Integer,Rational}s} -around them. - -ToDo: put in range checks for when converting ``@i@'' -(or should that be in the typechecker?) - -For numeric literals, we try to detect there use at a standard type -(@Int@, @Float@, etc.) are directly put in the right constructor. -[NB: down with the @App@ conversion.] - -See also below where we look for @DictApps@ for \tr{plusInt}, etc. +Translation for RecStmt's: +----------------------------- +We turn (RecStmt [v1,..vn] stmts) into: + + (v1,..,vn) <- mfix (\~(v1,..vn). do stmts + return (v1,..vn)) \begin{code} -dsLit :: HsLit -> DsM CoreExpr -dsLit (HsChar c) = returnDs (mkConApp charDataCon [mkLit (MachChar c)]) -dsLit (HsCharPrim c) = returnDs (mkLit (MachChar c)) -dsLit (HsString str) = mkStringLitFS str -dsLit (HsStringPrim s) = returnDs (mkLit (MachStr s)) -dsLit (HsInteger i) = mkIntegerLit i -dsLit (HsInt i) = returnDs (mkConApp intDataCon [mkIntLit i]) -dsLit (HsIntPrim i) = returnDs (mkIntLit i) -dsLit (HsFloatPrim f) = returnDs (mkLit (MachFloat f)) -dsLit (HsDoublePrim d) = returnDs (mkLit (MachDouble d)) -dsLit (HsLitLit str ty) - = ASSERT( maybeToBool maybe_ty ) - returnDs (wrap_fn (mkLit (MachLitLit str rep_ty))) - where - (maybe_ty, wrap_fn) = resultWrapper ty - Just rep_ty = maybe_ty - -dsLit (HsRat r ty) - = mkIntegerLit (numerator r) `thenDs` \ num -> - mkIntegerLit (denominator r) `thenDs` \ denom -> - returnDs (mkConApp ratio_data_con [Type integer_ty, num, denom]) - where - (ratio_data_con, integer_ty) - = case (splitAlgTyConApp_maybe ty) of - Just (tycon, [i_ty], [con]) - -> ASSERT(isIntegerTy i_ty && tycon `hasKey` ratioTyConKey) - (con, i_ty) - - _ -> (panic "ratio_data_con", panic "integer_ty") +dsRecStmt :: Type -- Monad type constructor :: * -> * + -> [(Name,Id)] -- Rebound Ids + -> [TypecheckedStmt] + -> [Id] -> [Id] -> [TypecheckedHsExpr] + -> TypecheckedStmt +dsRecStmt m_ty ds_meths stmts later_vars rec_vars rec_rets + = ASSERT( length vars == length rets ) + BindStmt tup_pat mfix_app noSrcLoc + where + vars@(var1:rest) = later_vars ++ rec_vars -- Always at least one + rets@(ret1:_) = map HsVar later_vars ++ rec_rets + one_var = null rest + + mfix_app = HsApp (TyApp (HsVar mfix_id) [tup_ty]) mfix_arg + mfix_arg = HsLam (mkSimpleMatch [tup_pat] body tup_ty noSrcLoc) + + tup_expr | one_var = ret1 + | otherwise = ExplicitTuple rets Boxed + tup_ty = mkCoreTupTy (map idType vars) + -- Deals with singleton case + tup_pat | one_var = VarPat var1 + | otherwise = LazyPat (TuplePat (map VarPat vars) Boxed) + + body = HsDo DoExpr (stmts ++ [return_stmt]) + [(n, HsVar id) | (n,id) <- ds_meths] -- A bit of a hack + (mkAppTy m_ty tup_ty) + noSrcLoc + + Var return_id = lookupReboundName ds_meths returnMName + Var mfix_id = lookupReboundName ds_meths mfixName + + return_stmt = ResultStmt return_app noSrcLoc + return_app = HsApp (TyApp (HsVar return_id) [tup_ty]) tup_expr \end{code} - - -