X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsExpr.lhs;h=0350843905f89f1f29320bcce3c97066dce532c5;hb=3721dd37a707d2aacb5cac814410a78096e28a2c;hp=881822930dd4d82f768222de5e10401f1205e618;hpb=278092c8eeb3835ad850b595afab0423fa890026;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsExpr.lhs b/ghc/compiler/deSugar/DsExpr.lhs index 8818229..0350843 100644 --- a/ghc/compiler/deSugar/DsExpr.lhs +++ b/ghc/compiler/deSugar/DsExpr.lhs @@ -4,18 +4,20 @@ \section[DsExpr]{Matching expressions (Exprs)} \begin{code} -module DsExpr ( dsExpr, dsLet, dsLit ) where +module DsExpr ( dsExpr, dsLExpr, dsLet, dsLit ) where #include "HsVersions.h" import Match ( matchWrapper, matchSimply ) import MatchLit ( dsLit ) -import DsBinds ( dsMonoBinds, AutoScc(..) ) +import DsBinds ( dsHsBinds, AutoScc(..) ) import DsGRHSs ( dsGuarded ) -import DsCCall ( dsCCall ) import DsListComp ( dsListComp, dsPArrComp ) -import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr) +import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr, + mkCoreTupTy, selectMatchVarL, + dsReboundNames, lookupReboundName ) +import DsArrows ( dsProcExpr ) import DsMonad #ifdef GHCI @@ -23,13 +25,8 @@ import DsMonad import DsMeta ( dsBracket ) #endif -import HsSyn ( failureFreePat, - HsExpr(..), Pat(..), HsLit(..), ArithSeqInfo(..), - Stmt(..), HsMatchContext(..), HsStmtContext(..), - Match(..), HsBinds(..), MonoBinds(..), HsConDetails(..), - mkSimpleMatch, isDoExpr - ) -import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, hsPatType ) +import HsSyn +import TcHsSyn ( hsPatType ) -- NB: The desugarer, which straddles the source and Core worlds, sometimes -- needs to see source types (newtypes etc), and sometimes not @@ -51,11 +48,14 @@ import DataCon ( DataCon, dataConWrapId, dataConFieldLabels, dataConInstOrigArg import DataCon ( isExistentialDataCon ) import Name ( Name ) import TyCon ( tyConDataCons ) -import TysWiredIn ( tupleCon, mkTupleTy ) +import TysWiredIn ( tupleCon ) import BasicTypes ( RecFlag(..), Boxity(..), ipNameName ) -import PrelNames ( toPName ) -import SrcLoc ( noSrcLoc ) +import PrelNames ( toPName, + returnMName, bindMName, thenMName, failMName, + mfixName ) +import SrcLoc ( Located(..), unLoc, getLoc, noLoc ) import Util ( zipEqual, zipWithEqual ) +import Bag ( bagToList ) import Outputable import FastString \end{code} @@ -79,21 +79,24 @@ 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 :: [HsBindGroup Id] -> CoreExpr -> DsM CoreExpr +dsLet groups body = foldlDs dsBindGroup body (reverse groups) -dsLet EmptyBinds body - = returnDs body +dsBindGroup :: CoreExpr -> HsBindGroup Id -> DsM CoreExpr +dsBindGroup body (HsIPBinds binds) + = foldlDs dsIPBind body binds + where + dsIPBind body (L _ (IPBind n e)) + = dsLExpr e `thenDs` \ e' -> + returnDs (Let (NonRec (ipNameName n) e') body) -dsLet (ThenBinds b1 b2) body - = dsLet b2 body `thenDs` \ body' -> - dsLet b1 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 bind@(MonoBind (AbsBinds [] [] exports inlines binds) sigs is_rec) body - | or [isUnLiftedType (idType g) | (_, g, l) <- exports] +dsBindGroup body bind@(HsBindGroup hsbinds sigs is_rec) + | [L _ (AbsBinds [] [] exports inlines binds)] <- bagToList hsbinds, + or [isUnLiftedType (idType g) | (_, g, l) <- exports] = ASSERT (case is_rec of {NonRecursive -> True; other -> False}) -- Unlifted bindings are always non-recursive -- and are always a Fun or Pat monobind @@ -101,35 +104,36 @@ dsLet bind@(MonoBind (AbsBinds [] [] exports inlines binds) sigs is_rec) body -- 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 $ + let + 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)) + in + case bagToList binds of + [L loc (FunBind (L _ fun) _ matches)] + -> putSrcSpanDs 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 $ + [L loc (PatBind pat grhss)] + -> putSrcSpanDs 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 - 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 -> +dsBindGroup body (HsBindGroup binds sigs is_rec) + = dsHsBinds NoSccs binds [] `thenDs` \ prs -> returnDs (Let (Rec prs) body) -- Use a Rec regardless of is_rec. - -- Why? Because it allows the MonoBinds to be all + -- Why? Because it allows the binds 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. @@ -147,9 +151,12 @@ dsLet (MonoBind binds sigs is_rec) body %************************************************************************ \begin{code} -dsExpr :: TypecheckedHsExpr -> DsM CoreExpr +dsLExpr :: LHsExpr Id -> DsM CoreExpr +dsLExpr (L loc e) = putSrcSpanDs loc $ dsExpr e -dsExpr (HsPar x) = dsExpr x +dsExpr :: HsExpr Id -> DsM CoreExpr + +dsExpr (HsPar x) = dsLExpr x dsExpr (HsVar var) = returnDs (Var var) dsExpr (HsIPVar ip) = returnDs (Var (ipNameName ip)) dsExpr (HsLit lit) = dsLit lit @@ -160,8 +167,8 @@ dsExpr expr@(HsLam a_Match) returnDs (mkLams binders matching_code) dsExpr expr@(HsApp fun arg) - = dsExpr fun `thenDs` \ core_fun -> - dsExpr arg `thenDs` \ core_arg -> + = dsLExpr fun `thenDs` \ core_fun -> + dsLExpr arg `thenDs` \ core_arg -> returnDs (core_fun `App` core_arg) \end{code} @@ -188,112 +195,100 @@ will sort it out. \begin{code} dsExpr (OpApp e1 op _ e2) - = dsExpr op `thenDs` \ core_op -> + = dsLExpr op `thenDs` \ core_op -> -- for the type of y, we need the type of op's 2nd argument - dsExpr e1 `thenDs` \ x_core -> - dsExpr e2 `thenDs` \ y_core -> + dsLExpr e1 `thenDs` \ x_core -> + dsLExpr e2 `thenDs` \ y_core -> returnDs (mkApps core_op [x_core, y_core]) dsExpr (SectionL expr op) - = dsExpr op `thenDs` \ core_op -> + = dsLExpr op `thenDs` \ core_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 -> + dsLExpr expr `thenDs` \ x_core -> newSysLocalDs x_ty `thenDs` \ x_id -> newSysLocalDs y_ty `thenDs` \ 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 +-- dsLExpr (SectionR op expr) -- \ x -> op x expr dsExpr (SectionR op expr) - = dsExpr op `thenDs` \ core_op -> + = dsLExpr op `thenDs` \ core_op -> -- 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 -> + dsLExpr expr `thenDs` \ y_core -> newSysLocalDs x_ty `thenDs` \ x_id -> 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 (HsCCall lbl args may_gc is_asm result_ty) - = mapDs dsExpr args `thenDs` \ core_args -> - dsCCall lbl core_args may_gc is_asm result_ty - -- dsCCall does all the unboxification, etc. - dsExpr (HsSCC cc expr) - = dsExpr expr `thenDs` \ core_expr -> + = dsLExpr expr `thenDs` \ core_expr -> getModuleDs `thenDs` \ mod_name -> returnDs (Note (SCC (mkUserCC cc mod_name)) core_expr) + +-- hdaume: core annotation + +dsExpr (HsCoreAnn fs expr) + = dsLExpr expr `thenDs` \ core_expr -> + returnDs (Note (CoreNote $ unpackFS fs) core_expr) + -- special case to handle unboxed tuple patterns. -dsExpr (HsCase discrim matches src_loc) +dsExpr (HsCase discrim matches) | all ubx_tuple_match matches - = putSrcLocDs src_loc $ - dsExpr discrim `thenDs` \ core_discrim -> + = dsLExpr 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)) + _ -> panic ("dsLExpr: tuple pattern:\n" ++ showSDoc (ppr matching_code)) where - ubx_tuple_match (Match [TuplePat ps Unboxed] _ _) = True + ubx_tuple_match (L _ (Match [L _ (TuplePat _ Unboxed)] _ _)) = True ubx_tuple_match _ = False -dsExpr (HsCase discrim matches src_loc) - = putSrcLocDs src_loc $ - dsExpr discrim `thenDs` \ core_discrim -> +dsExpr (HsCase discrim matches) + = dsLExpr 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' -> + = dsLExpr body `thenDs` \ body' -> dsLet binds body' -dsExpr (HsWith expr binds is_with) - = dsExpr expr `thenDs` \ expr' -> - foldlDs dsIPBind expr' binds - where - dsIPBind body (n, e) - = dsExpr e `thenDs` \ e' -> - returnDs (Let (NonRec (ipNameName n) e') body) - -- 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) +dsExpr (HsDo ListComp stmts _ result_ty) = -- Special case for list comprehensions - putSrcLocDs src_loc $ dsListComp stmts elt_ty where (_, [elt_ty]) = tcSplitTyConApp result_ty -dsExpr (HsDo do_or_lc stmts ids result_ty src_loc) +dsExpr (HsDo do_or_lc stmts ids result_ty) | isDoExpr do_or_lc - = putSrcLocDs src_loc $ - dsDo do_or_lc stmts ids result_ty + = dsDo do_or_lc stmts ids result_ty -dsExpr (HsDo PArrComp stmts _ result_ty src_loc) +dsExpr (HsDo PArrComp stmts _ result_ty) = -- Special case for array comprehensions - putSrcLocDs src_loc $ - dsPArrComp stmts elt_ty + dsPArrComp (map unLoc stmts) elt_ty where (_, [elt_ty]) = tcSplitTyConApp result_ty -dsExpr (HsIf guard_expr then_expr else_expr src_loc) - = putSrcLocDs src_loc $ - dsExpr guard_expr `thenDs` \ core_guard -> - dsExpr then_expr `thenDs` \ core_then -> - dsExpr else_expr `thenDs` \ core_else -> +dsExpr (HsIf guard_expr then_expr else_expr) + = dsLExpr guard_expr `thenDs` \ core_guard -> + dsLExpr then_expr `thenDs` \ core_then -> + dsLExpr else_expr `thenDs` \ core_else -> returnDs (mkIfThenElse core_guard core_then core_else) \end{code} @@ -303,11 +298,11 @@ dsExpr (HsIf guard_expr then_expr else_expr src_loc) % ~~~~~~~~~~~~~~~~~~~~~~~~~~~ \begin{code} dsExpr (TyLam tyvars expr) - = dsExpr expr `thenDs` \ core_expr -> + = dsLExpr expr `thenDs` \ core_expr -> returnDs (mkLams tyvars core_expr) dsExpr (TyApp expr tys) - = dsExpr expr `thenDs` \ core_expr -> + = dsLExpr expr `thenDs` \ core_expr -> returnDs (mkTyApps core_expr tys) \end{code} @@ -320,7 +315,7 @@ dsExpr (ExplicitList ty xs) = go xs where go [] = returnDs (mkNilExpr ty) - go (x:xs) = dsExpr x `thenDs` \ core_x -> + go (x:xs) = dsLExpr x `thenDs` \ core_x -> go xs `thenDs` \ core_xs -> returnDs (mkConsExpr ty core_x core_xs) @@ -340,45 +335,45 @@ dsExpr (ExplicitPArr ty xs) returnDs (mkApps (Var toP) [Type ty, coreList]) dsExpr (ExplicitTuple expr_list boxity) - = mapDs dsExpr expr_list `thenDs` \ core_exprs -> + = mappM dsLExpr expr_list `thenDs` \ core_exprs -> returnDs (mkConApp (tupleCon boxity (length expr_list)) (map (Type . exprType) core_exprs ++ core_exprs)) dsExpr (ArithSeqOut expr (From from)) - = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> + = dsLExpr expr `thenDs` \ expr2 -> + dsLExpr from `thenDs` \ from2 -> returnDs (App expr2 from2) dsExpr (ArithSeqOut expr (FromTo from two)) - = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> - dsExpr two `thenDs` \ two2 -> + = dsLExpr expr `thenDs` \ expr2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr two `thenDs` \ two2 -> returnDs (mkApps expr2 [from2, two2]) dsExpr (ArithSeqOut expr (FromThen from thn)) - = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> - dsExpr thn `thenDs` \ thn2 -> + = dsLExpr expr `thenDs` \ expr2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr thn `thenDs` \ 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 -> + = dsLExpr expr `thenDs` \ expr2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr thn `thenDs` \ thn2 -> + dsLExpr 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 -> + = dsLExpr expr `thenDs` \ expr2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr 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 -> + = dsLExpr expr `thenDs` \ expr2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr thn `thenDs` \ thn2 -> + dsLExpr two `thenDs` \ two2 -> returnDs (mkApps expr2 [from2, thn2, two2]) dsExpr (PArrSeqOut expr _) @@ -410,17 +405,17 @@ constructor @C@, setting all of @C@'s fields to bottom. \begin{code} dsExpr (RecordConOut data_con con_expr rbinds) - = dsExpr con_expr `thenDs` \ con_expr' -> + = dsLExpr con_expr `thenDs` \ con_expr' -> let (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 | (L _ sel_id, rhs) <- rbinds, lbl == recordSelectorFieldLabel sel_id] of (rhs:rhss) -> ASSERT( null rhss ) - dsExpr rhs + dsLExpr rhs [] -> mkErrorAppDs rEC_CON_ERROR_ID arg_ty (showSDoc (ppr lbl)) unlabelled_bottom arg_ty = mkErrorAppDs rEC_CON_ERROR_ID arg_ty "" @@ -428,8 +423,8 @@ dsExpr (RecordConOut data_con con_expr rbinds) in (if null labels - then mapDs unlabelled_bottom arg_tys - else mapDs mk_arg (zipEqual "dsExpr:RecordCon" arg_tys labels)) + then mappM unlabelled_bottom arg_tys + else mappM mk_arg (zipEqual "dsExpr:RecordCon" arg_tys labels)) `thenDs` \ con_args -> returnDs (mkApps con_expr' con_args) @@ -458,11 +453,10 @@ dictionaries. \begin{code} dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty []) - = dsExpr record_expr + = dsLExpr record_expr dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) - = getSrcLocDs `thenDs` \ src_loc -> - dsExpr record_expr `thenDs` \ record_expr' -> + = dsLExpr record_expr `thenDs` \ record_expr' -> -- Desugar the rbinds, and generate let-bindings if -- necessary so that we don't lose sharing @@ -472,10 +466,10 @@ dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) out_inst_tys = tcTyConAppArgs record_out_ty -- Newtype opaque mk_val_arg field old_arg_id - = case [rhs | (sel_id, rhs) <- rbinds, + = case [rhs | (L _ sel_id, rhs) <- rbinds, field == recordSelectorFieldLabel sel_id] of (rhs:rest) -> ASSERT(null rest) rhs - [] -> HsVar old_arg_id + [] -> nlHsVar old_arg_id mk_alt con = newSysLocalsDs (dataConInstOrigArgTys con in_inst_tys) `thenDs` \ arg_ids -> @@ -483,13 +477,14 @@ dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) let val_args = zipWithEqual "dsExpr:RecordUpd" mk_val_arg (dataConFieldLabels con) arg_ids - rhs = foldl HsApp (TyApp (HsVar (dataConWrapId con)) out_inst_tys) - val_args + rhs = foldl (\a b -> nlHsApp a b) + (noLoc $ TyApp (nlHsVar (dataConWrapId con)) + out_inst_tys) + val_args in - returnDs (mkSimpleMatch [ConPatOut con (PrefixCon (map VarPat arg_ids)) record_in_ty [] []] + returnDs (mkSimpleMatch [noLoc $ ConPatOut con (PrefixCon (map nlVarPat arg_ids)) record_in_ty [] []] rhs - record_out_ty - src_loc) + record_out_ty) in -- Record stuff doesn't work for existentials -- The type checker checks for this, but we need @@ -500,14 +495,15 @@ dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) -- 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 -> + mappM 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] + updated_fields = [ recordSelectorFieldLabel sel_id + | (L _ sel_id,_) <- rbinds] -- Get the type constructor from the first field label, -- so that we are sure it'll have all its DataCons @@ -533,13 +529,13 @@ dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) complicated; reminiscent of fully-applied constructors. \begin{code} dsExpr (DictLam dictvars expr) - = dsExpr expr `thenDs` \ core_expr -> + = dsLExpr expr `thenDs` \ core_expr -> returnDs (mkLams dictvars core_expr) ------------------ dsExpr (DictApp expr dicts) -- becomes a curried application - = dsExpr expr `thenDs` \ core_expr -> + = dsLExpr expr `thenDs` \ core_expr -> returnDs (foldl (\f d -> f `App` (Var d)) core_expr dicts) \end{code} @@ -550,9 +546,11 @@ Here is where we desugar the Template Haskell brackets and escapes #ifdef GHCI /* Only if bootstrapping */ dsExpr (HsBracketOut x ps) = dsBracket x ps -dsExpr (HsSplice n e) = pprPanic "dsExpr:splice" (ppr e) +dsExpr (HsSpliceE s) = pprPanic "dsExpr:splice" (ppr s) #endif +-- Arrow notation extension +dsExpr (HsProc pat cmd) = dsProcExpr pat cmd \end{code} @@ -569,83 +567,70 @@ dsExpr (PArrSeqIn _) = panic "dsExpr:PArrSeqIn" %-------------------------------------------------------------------- -Basically does the translation given in the Haskell~1.3 report: +Desugar 'do' and 'mdo' expressions (NOT list comprehensions, they're +handled in DsListComp). Basically does the translation given in the +Haskell 98 report: \begin{code} dsDo :: HsStmtContext Name - -> [TypecheckedStmt] - -> [Id] -- id for: [return,fail,>>=,>>] and possibly mfixName - -> Type -- Element type; the whole expression has type (m t) + -> [LStmt Id] + -> 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 ids result_ty - = let - (return_id : fail_id : bind_id : then_id : _) = ids + = 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 -- 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 (Var return_id) [Type b_ty, expr2]) + go [ResultStmt expr] = dsLExpr expr - go (ExprStmt expr a_ty locn : stmts) - | is_do -- Do expression - = do_expr expr locn `thenDs` \ expr2 -> - go stmts `thenDs` \ rest -> - returnDs (mkApps (Var 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 = "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 a_ty : stmts) + = dsLExpr expr `thenDs` \ expr2 -> + go stmts `thenDs` \ rest -> + returnDs (mkApps then_id [Type a_ty, Type b_ty, expr2, rest]) - go (LetStmt binds : stmts ) + go (LetStmt binds : stmts) = go stmts `thenDs` \ rest -> dsLet binds rest - go (BindStmt pat expr locn : stmts) - = putSrcLocDs locn $ - dsExpr expr `thenDs` \ expr2 -> + go (BindStmt pat expr : stmts) + = go stmts `thenDs` \ body -> + dsLExpr expr `thenDs` \ rhs -> + mkStringLit (mk_msg (getLoc pat)) `thenDs` \ core_msg -> let + -- 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 - fail_expr = HsApp (TyApp (HsVar fail_id) [b_ty]) - (HsLit (HsString (mkFastString msg))) - msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn) - main_match = mkSimpleMatch [pat] - (HsDo do_or_lc stmts ids result_ty locn) - result_ty locn - the_matches - | failureFreePat pat = [main_match] - | otherwise = - [ main_match - , mkSimpleMatch [WildPat a_ty] fail_expr result_ty locn - ] in - matchWrapper (StmtCtxt do_or_lc) the_matches `thenDs` \ (binders, matching_code) -> - returnDs (mkApps (Var bind_id) [Type a_ty, Type b_ty, expr2, - mkLams binders matching_code]) + selectMatchVarL 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_vars rec_stmts : stmts) + go (RecStmt rec_stmts later_vars rec_vars rec_rets : stmts) = go (bind_stmt : stmts) where - bind_stmt = dsRecStmt m_ty ids rec_vars rec_stmts + bind_stmt = dsRecStmt m_ty ds_meths rec_stmts later_vars rec_vars rec_rets in - go stmts + go (map unLoc stmts) `thenDs` \ stmts_code -> + returnDs (foldr Let stmts_code meth_binds) where - do_expr expr locn = putSrcLocDs locn (dsExpr expr) + mk_msg locn = "Pattern match failure in do expression at " ++ showSDoc (ppr locn) \end{code} Translation for RecStmt's: @@ -657,30 +642,35 @@ We turn (RecStmt [v1,..vn] stmts) into: \begin{code} dsRecStmt :: Type -- Monad type constructor :: * -> * - -> [Id] -- Ids for: [return,fail,>>=,>>,mfix] - -> [Id] -> [TypecheckedStmt] -- Guts of the RecStmt - -> TypecheckedStmt -dsRecStmt m_ty ids@[return_id, _, _, _, mfix_id] vars stmts - = BindStmt tup_pat mfix_app noSrcLoc + -> [(Name,Id)] -- Rebound Ids + -> [LStmt Id] + -> [Id] -> [Id] -> [LHsExpr Id] + -> Stmt Id +dsRecStmt m_ty ds_meths stmts later_vars rec_vars rec_rets + = ASSERT( length vars == length rets ) + BindStmt tup_pat mfix_app where - (var1:rest) = vars -- Always at least one - 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 = HsVar var1 - | otherwise = ExplicitTuple (map HsVar vars) Boxed - tup_ty | one_var = idType var1 - | otherwise = mkTupleTy Boxed (length vars) (map idType vars) - tup_pat | one_var = VarPat var1 - | otherwise = LazyPat (TuplePat (map VarPat vars) Boxed) - - body = HsDo DoExpr (stmts ++ [return_stmt]) - ids -- Don't need the mfix, but it does no harm + vars@(var1:rest) = later_vars ++ rec_vars -- Always at least one + rets@(ret1:_) = map nlHsVar later_vars ++ rec_rets + one_var = null rest + + mfix_app = nlHsApp (noLoc $ TyApp (nlHsVar mfix_id) [tup_ty]) mfix_arg + mfix_arg = noLoc $ HsLam (mkSimpleMatch [tup_pat] body tup_ty) + + tup_expr | one_var = ret1 + | otherwise = noLoc $ ExplicitTuple rets Boxed + tup_ty = mkCoreTupTy (map idType vars) + -- Deals with singleton case + tup_pat | one_var = nlVarPat var1 + | otherwise = noLoc $ LazyPat (noLoc $ TuplePat (map nlVarPat vars) Boxed) + + body = noLoc $ HsDo DoExpr (stmts ++ [return_stmt]) + [(n, nlHsVar id) | (n,id) <- ds_meths] -- A bit of a hack (mkAppTy m_ty tup_ty) - noSrcLoc - return_stmt = ResultStmt return_app noSrcLoc - return_app = HsApp (TyApp (HsVar return_id) [tup_ty]) tup_expr + Var return_id = lookupReboundName ds_meths returnMName + Var mfix_id = lookupReboundName ds_meths mfixName + + return_stmt = noLoc $ ResultStmt return_app + return_app = nlHsApp (noLoc $ TyApp (nlHsVar return_id) [tup_ty]) tup_expr \end{code}