X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsExpr.lhs;h=afdf16641fce541874577f8242ae1e0289bf3d5c;hb=3160f854580e6d8df412c8cd34d93bae27175d67;hp=1e374ce353ec9560c3e3aa38c7cf90387788f76e;hpb=2c8f04b5b883db74f449dfc8c224929fe28b027d;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsExpr.lhs b/ghc/compiler/deSugar/DsExpr.lhs index 1e374ce..afdf166 100644 --- a/ghc/compiler/deSugar/DsExpr.lhs +++ b/ghc/compiler/deSugar/DsExpr.lhs @@ -1,22 +1,20 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[DsExpr]{Matching expressions (Exprs)} \begin{code} -module DsExpr ( dsExpr ) where +module DsExpr ( dsExpr, dsLet ) where #include "HsVersions.h" -import {-# SOURCE #-} DsBinds (dsBinds ) import HsSyn ( failureFreePat, HsExpr(..), OutPat(..), HsLit(..), ArithSeqInfo(..), - Stmt(..), DoOrListComp(..), Match(..), HsBinds, HsType, Fixity, - GRHSsAndBinds + Stmt(..), StmtCtxt(..), Match(..), HsBinds(..), MonoBinds(..), + mkSimpleMatch ) import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, - TypecheckedRecordBinds, TypecheckedPat, TypecheckedStmt, maybeBoxedPrimType @@ -24,41 +22,90 @@ import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, import CoreSyn import DsMonad +import DsBinds ( dsMonoBinds ) +import DsGRHSs ( dsGuarded ) import DsCCall ( dsCCall ) import DsListComp ( dsListComp ) -import DsUtils ( mkAppDs, mkConDs, dsExprToAtomGivenTy, - mkErrorAppDs, showForErr, DsCoreArg - ) -import Match ( matchWrapper ) +import DsUtils ( mkErrorAppDs ) +import Match ( matchWrapper, matchSimply ) -import CoreUtils ( coreExprType, mkCoreIfThenElse ) +import CoreUtils ( coreExprType ) import CostCentre ( mkUserCC ) import FieldLabel ( FieldLabel ) -import Id ( dataConTyCon, dataConArgTys, dataConFieldLabels, - recordSelectorFieldLabel, Id - ) -import Literal ( mkMachInt, Literal(..) ) -import Name ( Name{--O only-} ) -import PrelVals ( rEC_CON_ERROR_ID, rEC_UPD_ERROR_ID ) +import Id ( Id, idType, recordSelectorFieldLabel ) +import Const ( Con(..) ) +import DataCon ( DataCon, dataConId, dataConTyCon, dataConArgTys, dataConFieldLabels ) +import Const ( mkMachInt, Literal(..), mkStrLit ) +import PrelVals ( rEC_CON_ERROR_ID, rEC_UPD_ERROR_ID, iRREFUT_PAT_ERROR_ID ) import TyCon ( isNewTyCon ) -import Type ( splitFunTys, typePrimRep, mkTyConApp, +import DataCon ( isExistentialDataCon ) +import Type ( splitFunTys, mkTyConApp, splitAlgTyConApp, splitTyConApp_maybe, - splitAppTy, Type + splitAppTy, isUnLiftedType, Type ) -import TysWiredIn ( tupleCon, nilDataCon, consDataCon, listTyCon, mkListTy, - charDataCon, charTy +import TysWiredIn ( tupleCon, unboxedTupleCon, + consDataCon, listTyCon, mkListTy, + charDataCon, charTy, stringTy ) -import TyVar ( GenTyVar{-instance Eq-} ) +import BasicTypes ( RecFlag(..) ) import Maybes ( maybeToBool ) -import Util ( zipEqual ) +import Util ( zipEqual, zipWithEqual ) import Outputable - -mk_nil_con ty = mkCon nilDataCon [ty] [] -- micro utility... \end{code} -The funny business to do with variables is that we look them up in the -Id-to-Id and Id-to-Id maps that the monadery is carrying -around; if we get hits, we use the value accordingly. + +%************************************************************************ +%* * +\subsection{dsLet} +%* * +%************************************************************************ + +@dsLet@ is a match-result transformer, taking the MatchResult for the body +and transforming it into one for the let-bindings enclosing the body. + +This may seem a bit odd, but (source) let bindings can contain unboxed +binds like + + C x# = e + +This must be transformed to a case expression and, if the type has +more than one constructor, may fail. + +\begin{code} +dsLet :: TypecheckedHsBinds -> CoreExpr -> DsM CoreExpr + +dsLet EmptyBinds body + = returnDs body + +dsLet (ThenBinds b1 b2) body + = dsLet b2 body `thenDs` \ body' -> + dsLet b1 body' + +-- Special case for bindings which bind unlifted variables +dsLet (MonoBind (AbsBinds [] [] binder_triples (PatMonoBind pat grhss loc)) sigs is_rec) body + | or [isUnLiftedType (idType g) | (_, g, l) <- binder_triples] + = 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 + where + result_ty = coreExprType body + +-- Ordinary case for bindings +dsLet (MonoBind binds sigs is_rec) body + = dsMonoBinds False binds [] `thenDs` \ prs -> + case is_rec of + Recursive -> returnDs (Let (Rec prs) body) + NonRecursive -> returnDs (foldr mk_let body prs) + where + mk_let (bndr,rhs) body = Let (NonRec bndr rhs) body +\end{code} %************************************************************************ %* * @@ -69,7 +116,7 @@ around; if we get hits, we use the value accordingly. \begin{code} dsExpr :: TypecheckedHsExpr -> DsM CoreExpr -dsExpr e@(HsVar var) = dsId var +dsExpr e@(HsVar var) = returnDs (Var var) \end{code} %************************************************************************ @@ -96,14 +143,16 @@ See also below where we look for @DictApps@ for \tr{plusInt}, etc. \begin{code} dsExpr (HsLitOut (HsString s) _) | _NULL_ s - = returnDs (mk_nil_con charTy) + = returnDs (mkNilExpr charTy) | _LENGTH_ s == 1 = let - the_char = mkCon charDataCon [] [LitArg (MachChar (_HEAD_ s))] - the_nil = mk_nil_con charTy + the_char = mkConApp charDataCon [mkLit (MachChar (_HEAD_ s))] + the_nil = mkNilExpr charTy + the_cons = mkConApp consDataCon [Type charTy, the_char, the_nil] in - mkConDs consDataCon [TyArg charTy, VarArg the_char, VarArg the_nil] + returnDs the_cons + -- "_" => build (\ c n -> c 'c' n) -- LATER @@ -132,61 +181,59 @@ dsExpr (HsLitOut (HsString str) _) -- the Core-to-STG pass will wrap it in an application of "unpackCStringId". dsExpr (HsLitOut (HsString str) _) - = returnDs (Lit (NoRepStr str)) + = returnDs (mkLit (NoRepStr str stringTy)) -dsExpr (HsLitOut (HsLitLit s) ty) - = returnDs ( mkCon data_con [] [LitArg (MachLitLit s kind)] ) +dsExpr (HsLitOut (HsLitLit str) ty) + = returnDs ( mkConApp data_con [mkLit (MachLitLit str prim_ty)] ) where - (data_con, kind) + (data_con, prim_ty) = case (maybeBoxedPrimType ty) of - Just (boxing_data_con, prim_ty) - -> (boxing_data_con, typePrimRep prim_ty) + Just (boxing_data_con, prim_ty) -> (boxing_data_con, prim_ty) Nothing -> pprPanic "ERROR: ``literal-literal'' not a single-constructor type: " - (hcat [ptext s, text "; type: ", ppr ty]) + (hcat [ptext str, text "; type: ", ppr ty]) dsExpr (HsLitOut (HsInt i) ty) - = returnDs (Lit (NoRepInteger i ty)) + = returnDs (mkLit (NoRepInteger i ty)) dsExpr (HsLitOut (HsFrac r) ty) - = returnDs (Lit (NoRepRational r ty)) + = returnDs (mkLit (NoRepRational r ty)) -- others where we know what to do: dsExpr (HsLitOut (HsIntPrim i) _) - = if (i >= toInteger minInt && i <= toInteger maxInt) then - returnDs (Lit (mkMachInt i)) - else - error ("ERROR: Int constant " ++ show i ++ out_of_range_msg) + | (i >= toInteger minInt && i <= toInteger maxInt) + = returnDs (mkLit (mkMachInt i)) + | otherwise + = error ("ERROR: Int constant " ++ show i ++ out_of_range_msg) dsExpr (HsLitOut (HsFloatPrim f) _) - = returnDs (Lit (MachFloat f)) + = returnDs (mkLit (MachFloat f)) -- ToDo: range checking needed! dsExpr (HsLitOut (HsDoublePrim d) _) - = returnDs (Lit (MachDouble d)) + = returnDs (mkLit (MachDouble d)) -- ToDo: range checking needed! dsExpr (HsLitOut (HsChar c) _) - = returnDs ( mkCon charDataCon [] [LitArg (MachChar c)] ) + = returnDs ( mkConApp charDataCon [mkLit (MachChar c)] ) dsExpr (HsLitOut (HsCharPrim c) _) - = returnDs (Lit (MachChar c)) + = returnDs (mkLit (MachChar c)) dsExpr (HsLitOut (HsStringPrim s) _) - = returnDs (Lit (MachStr s)) + = returnDs (mkLit (MachStr s)) -- end of literals magic. -- dsExpr expr@(HsLam a_Match) = matchWrapper LambdaMatch [a_Match] "lambda" `thenDs` \ (binders, matching_code) -> - returnDs ( mkValLam binders matching_code ) + returnDs (mkLams binders matching_code) dsExpr expr@(HsApp fun arg) = dsExpr fun `thenDs` \ core_fun -> dsExpr arg `thenDs` \ core_arg -> - dsExprToAtomGivenTy core_arg (coreExprType core_arg) $ \ atom_arg -> - returnDs (core_fun `App` atom_arg) + returnDs (core_fun `App` core_arg) \end{code} @@ -220,9 +267,7 @@ dsExpr (OpApp e1 op _ e2) in dsExpr e1 `thenDs` \ x_core -> dsExpr e2 `thenDs` \ y_core -> - dsExprToAtomGivenTy x_core x_ty $ \ x_atom -> - dsExprToAtomGivenTy y_core y_ty $ \ y_atom -> - returnDs (core_op `App` x_atom `App` y_atom) + returnDs (mkApps core_op [x_core, y_core]) dsExpr (SectionL expr op) = dsExpr op `thenDs` \ core_op -> @@ -231,10 +276,11 @@ dsExpr (SectionL expr op) (x_ty:y_ty:_, _) = splitFunTys (coreExprType core_op) in dsExpr expr `thenDs` \ x_core -> - dsExprToAtomGivenTy x_core x_ty $ \ x_atom -> - + newSysLocalDs x_ty `thenDs` \ x_id -> newSysLocalDs y_ty `thenDs` \ y_id -> - returnDs (mkValLam [y_id] (core_op `App` x_atom `App` VarArg y_id)) + + returnDs (bindNonRec x_id x_core $ + Lam y_id (mkApps core_op [Var x_id, Var y_id])) -- dsExpr (SectionR op expr) -- \ x -> op x expr dsExpr (SectionR op expr) @@ -243,11 +289,12 @@ dsExpr (SectionR op expr) let (x_ty:y_ty:_, _) = splitFunTys (coreExprType core_op) in - dsExpr expr `thenDs` \ y_expr -> - dsExprToAtomGivenTy y_expr y_ty $ \ y_atom -> - + dsExpr expr `thenDs` \ y_core -> newSysLocalDs x_ty `thenDs` \ x_id -> - returnDs (mkValLam [x_id] (core_op `App` VarArg x_id `App` y_atom)) + newSysLocalDs y_ty `thenDs` \ y_id -> + + returnDs (bindNonRec y_id y_core $ + Lam x_id (mkApps core_op [Var x_id, Var y_id])) dsExpr (CCall label args may_gc is_asm result_ty) = mapDs dsExpr args `thenDs` \ core_args -> @@ -259,18 +306,29 @@ dsExpr (HsSCC cc expr) getModuleAndGroupDs `thenDs` \ (mod_name, group_name) -> returnDs (Note (SCC (mkUserCC cc mod_name group_name)) core_expr) -dsExpr expr@(HsCase discrim matches src_loc) - = putSrcLocDs src_loc $ +-- special case to handle unboxed tuple patterns + +dsExpr (HsCase discrim matches@[Match _ [TuplePat ps boxed] _ _] src_loc) + | all var_pat ps + = putSrcLocDs src_loc $ dsExpr discrim `thenDs` \ core_discrim -> matchWrapper CaseMatch matches "case" `thenDs` \ ([discrim_var], matching_code) -> - returnDs ( mkCoLetAny (NonRec discrim_var core_discrim) 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)) -dsExpr (HsLet binds expr) - = dsBinds False binds `thenDs` \ core_binds -> - dsExpr expr `thenDs` \ core_expr -> - returnDs ( mkCoLetsAny core_binds core_expr ) +dsExpr (HsCase discrim matches src_loc) + = putSrcLocDs src_loc $ + dsExpr discrim `thenDs` \ core_discrim -> + matchWrapper CaseMatch matches "case" `thenDs` \ ([discrim_var], matching_code) -> + returnDs (bindNonRec discrim_var core_discrim matching_code) -dsExpr (HsDoOut do_or_lc stmts return_id then_id zero_id result_ty src_loc) +dsExpr (HsLet binds body) + = dsExpr body `thenDs` \ body' -> + dsLet binds body' + +dsExpr (HsDoOut do_or_lc stmts return_id then_id fail_id result_ty src_loc) | maybeToBool maybe_list_comp = -- Special case for list comprehensions putSrcLocDs src_loc $ @@ -278,7 +336,7 @@ dsExpr (HsDoOut do_or_lc stmts return_id then_id zero_id result_ty src_loc) | otherwise = putSrcLocDs src_loc $ - dsDo do_or_lc stmts return_id then_id zero_id result_ty + dsDo do_or_lc stmts return_id then_id fail_id result_ty where maybe_list_comp = case (do_or_lc, splitTyConApp_maybe result_ty) of @@ -297,7 +355,7 @@ dsExpr (HsIf guard_expr then_expr else_expr src_loc) dsExpr guard_expr `thenDs` \ core_guard -> dsExpr then_expr `thenDs` \ core_then -> dsExpr else_expr `thenDs` \ core_else -> - returnDs (mkCoreIfThenElse core_guard core_then core_else) + returnDs (mkIfThenElse core_guard core_then core_else) \end{code} @@ -306,11 +364,11 @@ Type lambda and application \begin{code} dsExpr (TyLam tyvars expr) = dsExpr expr `thenDs` \ core_expr -> - returnDs (mkTyLam tyvars core_expr) + returnDs (mkLams tyvars core_expr) dsExpr (TyApp expr tys) = dsExpr expr `thenDs` \ core_expr -> - returnDs (mkTyApp core_expr tys) + returnDs (mkTyApps core_expr tys) \end{code} @@ -322,20 +380,17 @@ dsExpr (ExplicitListOut ty xs) where list_ty = mkListTy ty - -- xs can ocasaionlly be huge, so don't try to take - -- coreExprType of core_xs, as dsArgToAtom does - -- (that gives a quadratic algorithm) - go [] = returnDs (mk_nil_con ty) + go [] = returnDs (mkNilExpr ty) go (x:xs) = dsExpr x `thenDs` \ core_x -> - dsExprToAtomGivenTy core_x ty $ \ arg_x -> go xs `thenDs` \ core_xs -> - dsExprToAtomGivenTy core_xs list_ty $ \ arg_xs -> - returnDs (Con consDataCon [TyArg ty, arg_x, arg_xs]) + returnDs (mkConApp consDataCon [Type ty, core_x, core_xs]) -dsExpr (ExplicitTuple expr_list) +dsExpr (ExplicitTuple expr_list boxed) = mapDs dsExpr expr_list `thenDs` \ core_exprs -> - mkConDs (tupleCon (length expr_list)) - (map (TyArg . coreExprType) core_exprs ++ map VarArg core_exprs) + returnDs (mkConApp ((if boxed + then tupleCon + else unboxedTupleCon) (length expr_list)) + (map (Type . coreExprType) core_exprs ++ core_exprs)) dsExpr (HsCon con_id [ty] [arg]) | isNewTyCon tycon @@ -347,31 +402,31 @@ dsExpr (HsCon con_id [ty] [arg]) dsExpr (HsCon con_id tys args) = mapDs dsExpr args `thenDs` \ args2 -> - mkConDs con_id (map TyArg tys ++ map VarArg args2) + returnDs (mkConApp con_id (map Type tys ++ args2)) dsExpr (ArithSeqOut expr (From from)) = dsExpr expr `thenDs` \ expr2 -> dsExpr from `thenDs` \ from2 -> - mkAppDs expr2 [VarArg from2] + returnDs (App expr2 from2) dsExpr (ArithSeqOut expr (FromTo from two)) = dsExpr expr `thenDs` \ expr2 -> dsExpr from `thenDs` \ from2 -> dsExpr two `thenDs` \ two2 -> - mkAppDs expr2 [VarArg from2, VarArg two2] + returnDs (mkApps expr2 [from2, two2]) dsExpr (ArithSeqOut expr (FromThen from thn)) = dsExpr expr `thenDs` \ expr2 -> dsExpr from `thenDs` \ from2 -> dsExpr thn `thenDs` \ thn2 -> - mkAppDs expr2 [VarArg from2, VarArg thn2] + returnDs (mkApps expr2 [from2, thn2]) dsExpr (ArithSeqOut expr (FromThenTo from thn two)) = dsExpr expr `thenDs` \ expr2 -> dsExpr from `thenDs` \ from2 -> dsExpr thn `thenDs` \ thn2 -> dsExpr two `thenDs` \ two2 -> - mkAppDs expr2 [VarArg from2, VarArg thn2, VarArg two2] + returnDs (mkApps expr2 [from2, thn2, two2]) \end{code} Record construction and update @@ -392,7 +447,7 @@ before printing it as \begin{code} -dsExpr (RecordCon con_id con_expr rbinds) +dsExpr (RecordConOut data_con con_expr rbinds) = dsExpr con_expr `thenDs` \ con_expr' -> let (arg_tys, _) = splitFunTys (coreExprType con_expr') @@ -402,10 +457,10 @@ dsExpr (RecordCon con_id con_expr rbinds) lbl == recordSelectorFieldLabel sel_id] of (rhs:rhss) -> ASSERT( null rhss ) dsExpr rhs - [] -> mkErrorAppDs rEC_CON_ERROR_ID arg_ty (showForErr lbl) + [] -> mkErrorAppDs rEC_CON_ERROR_ID arg_ty (showSDoc (ppr lbl)) in - mapDs mk_arg (zipEqual "dsExpr:RecordCon" arg_tys (dataConFieldLabels con_id)) `thenDs` \ con_args -> - mkAppDs con_expr' (map VarArg con_args) + mapDs mk_arg (zipEqual "dsExpr:RecordCon" arg_tys (dataConFieldLabels data_con)) `thenDs` \ con_args -> + returnDs (mkApps con_expr' con_args) \end{code} Record update is a little harder. Suppose we have the decl: @@ -431,11 +486,17 @@ dictionaries. \begin{code} dsExpr (RecordUpdOut record_expr record_out_ty dicts rbinds) - = dsExpr record_expr `thenDs` \ record_expr' -> + = dsExpr record_expr `thenDs` \ record_expr' -> -- Desugar the rbinds, and generate let-bindings if -- necessary so that we don't lose sharing - dsRbinds rbinds $ \ rbinds' -> + + let + ds_rbind (sel_id, rhs, pun_flag) + = dsExpr rhs `thenDs` \ rhs' -> + returnDs (recordSelectorFieldLabel sel_id, rhs') + in + mapDs ds_rbind rbinds `thenDs` \ rbinds' -> let record_in_ty = coreExprType record_expr' (tycon, in_inst_tys, cons) = splitAlgTyConApp record_in_ty @@ -443,37 +504,39 @@ dsExpr (RecordUpdOut record_expr record_out_ty dicts rbinds) cons_to_upd = filter has_all_fields cons -- initial_args are passed to every constructor - initial_args = map TyArg out_inst_tys ++ map VarArg dicts + initial_args = map Type out_inst_tys ++ map Var dicts - mk_val_arg (field, arg_id) - = case [arg | (f, arg) <- rbinds', - field == recordSelectorFieldLabel f] of - (arg:args) -> ASSERT(null args) - arg - [] -> VarArg arg_id + mk_val_arg field old_arg_id + = case [rhs | (f, rhs) <- rbinds', field == f] of + (rhs:rest) -> ASSERT(null rest) rhs + [] -> Var old_arg_id mk_alt con = newSysLocalsDs (dataConArgTys con in_inst_tys) `thenDs` \ arg_ids -> let - val_args = map mk_val_arg (zipEqual "dsExpr:RecordUpd" (dataConFieldLabels con) arg_ids) + val_args = zipWithEqual "dsExpr:RecordUpd" mk_val_arg + (dataConFieldLabels con) arg_ids + rhs = mkApps (mkApps (Var (dataConId con)) initial_args) val_args in - returnDs (con, arg_ids, mkGenApp (mkGenApp (Var con) initial_args) val_args) + returnDs (DataCon con, arg_ids, rhs) mk_default | length cons_to_upd == length cons - = returnDs NoDefault + = returnDs [] | otherwise - = newSysLocalDs record_in_ty `thenDs` \ deflt_id -> - mkErrorAppDs rEC_UPD_ERROR_ID record_out_ty "" `thenDs` \ err -> - returnDs (BindDefault deflt_id err) + = mkErrorAppDs rEC_UPD_ERROR_ID record_out_ty "" `thenDs` \ err -> + returnDs [(DEFAULT, [], err)] in + -- Record stuff doesn't work for existentials + ASSERT( all (not . isExistentialDataCon) cons ) + + newSysLocalDs record_in_ty `thenDs` \ case_bndr -> mapDs mk_alt cons_to_upd `thenDs` \ alts -> mk_default `thenDs` \ deflt -> - returnDs (Case record_expr' (AlgAlts alts deflt)) - + returnDs (Case record_expr' case_bndr (alts ++ deflt)) where - has_all_fields :: Id -> Bool + has_all_fields :: DataCon -> Bool has_all_fields con_id = all ok rbinds where @@ -489,19 +552,17 @@ complicated; reminiscent of fully-applied constructors. \begin{code} dsExpr (DictLam dictvars expr) = dsExpr expr `thenDs` \ core_expr -> - returnDs (mkValLam dictvars core_expr) + returnDs (mkLams dictvars core_expr) ------------------ dsExpr (DictApp expr dicts) -- becomes a curried application - = mapDs lookupEnvDs dicts `thenDs` \ core_dicts -> - dsExpr expr `thenDs` \ core_expr -> - returnDs (foldl (\f d -> f `App` (VarArg d)) core_expr core_dicts) + = dsExpr expr `thenDs` \ core_expr -> + returnDs (foldl (\f d -> f `App` (Var d)) core_expr dicts) \end{code} \begin{code} - #ifdef DEBUG -- HsSyn constructs that just shouldn't be here: dsExpr (HsDo _ _ _) = panic "dsExpr:HsDo" @@ -514,58 +575,36 @@ out_of_range_msg -- ditto = " out of range: [" ++ show minInt ++ ", " ++ show maxInt ++ "]\n" \end{code} - %-------------------------------------------------------------------- -\begin{code} -dsId v - = lookupEnvDs v `thenDs` \ v' -> - returnDs (Var v') -\end{code} - -\begin{code} -dsRbinds :: TypecheckedRecordBinds -- The field bindings supplied - -> ([(Id, CoreArg)] -> DsM CoreExpr) -- A continuation taking the field - -- bindings with atomic rhss - -> DsM CoreExpr -- The result of the continuation, - -- wrapped in suitable Lets - -dsRbinds [] continue_with - = continue_with [] - -dsRbinds ((sel_id, rhs, pun_flag) : rbinds) continue_with - = dsExpr rhs `thenDs` \ rhs' -> - dsExprToAtomGivenTy rhs' (coreExprType rhs') $ \ rhs_atom -> - dsRbinds rbinds $ \ rbinds' -> - continue_with ((sel_id, rhs_atom) : rbinds') -\end{code} - Basically does the translation given in the Haskell~1.3 report: + \begin{code} -dsDo :: DoOrListComp +dsDo :: StmtCtxt -> [TypecheckedStmt] -> Id -- id for: return m -> Id -- id for: (>>=) m - -> Id -- id for: zero m + -> Id -- id for: fail m -> Type -- Element type; the whole expression has type (m t) -> DsM CoreExpr -dsDo do_or_lc stmts return_id then_id zero_id result_ty - = dsId return_id `thenDs` \ return_ds -> - dsId then_id `thenDs` \ then_ds -> - dsId zero_id `thenDs` \ zero_ds -> - let +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) go [ReturnStmt expr] = dsExpr expr `thenDs` \ expr2 -> - mkAppDs return_ds [TyArg b_ty, VarArg expr2] + returnDs (mkApps (Var return_id) [Type b_ty, expr2]) go (GuardStmt expr locn : stmts) = do_expr expr locn `thenDs` \ expr2 -> go stmts `thenDs` \ rest -> - mkAppDs zero_ds [TyArg b_ty] `thenDs` \ zero_expr -> - returnDs (mkCoreIfThenElse expr2 rest zero_expr) + let msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn) in + returnDs (mkIfThenElse expr2 + rest + (App (App (Var fail_id) + (Type b_ty)) + (mkLit (mkStrLit msg stringTy)))) go (ExprStmt expr locn : stmts) = do_expr expr locn `thenDs` \ expr2 -> @@ -577,31 +616,34 @@ dsDo do_or_lc stmts return_id then_id zero_id result_ty else go stmts `thenDs` \ rest -> newSysLocalDs a_ty `thenDs` \ ignored_result_id -> - mkAppDs then_ds [TyArg a_ty, TyArg b_ty, VarArg expr2, - VarArg (mkValLam [ignored_result_id] rest)] + returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2, + Lam ignored_result_id rest]) go (LetStmt binds : stmts ) - = dsBinds False binds `thenDs` \ binds2 -> - go stmts `thenDs` \ rest -> - returnDs (mkCoLetsAny binds2 rest) - + = go stmts `thenDs` \ rest -> + dsLet binds rest + go (BindStmt pat expr locn : stmts) = putSrcLocDs locn $ dsExpr expr `thenDs` \ expr2 -> let (_, a_ty) = splitAppTy (coreExprType expr2) -- Must be of form (m a) - zero_expr = TyApp (HsVar zero_id) [b_ty] - main_match = PatMatch pat (SimpleMatch ( - HsDoOut do_or_lc stmts return_id then_id zero_id result_ty locn)) + fail_expr = HsApp (TyApp (HsVar fail_id) [b_ty]) (HsLitOut (HsString (_PK_ msg)) stringTy) + msg = "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 - = if failureFreePat pat - then [main_match] - else [main_match, PatMatch (WildPat a_ty) (SimpleMatch zero_expr)] + | failureFreePat pat = [main_match] + | otherwise = + [ main_match + , mkSimpleMatch [WildPat a_ty] fail_expr (Just result_ty) locn + ] in matchWrapper DoBindMatch the_matches match_msg `thenDs` \ (binders, matching_code) -> - mkAppDs then_ds [TyArg a_ty, TyArg b_ty, - VarArg expr2, VarArg (mkValLam binders matching_code)] + returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2, + mkLams binders matching_code]) in go stmts @@ -612,3 +654,10 @@ dsDo do_or_lc stmts return_id then_id zero_id result_ty DoStmt -> "`do' statement" ListComp -> "comprehension" \end{code} + +\begin{code} +var_pat (WildPat _) = True +var_pat (VarPat _) = True +var_pat _ = False +\end{code} +