X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsExpr.lhs;h=71df1b196393323142b4f1e0ee26619eb065668e;hb=8344b1e4a6e20d289cee53a4b25b18c6c28449bf;hp=2ce9440ec8ed191afada5fc9380ce0ee8b9ca141;hpb=d069cec2bd92d4156aeab80f7eb1f222a82e4103;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsExpr.lhs b/ghc/compiler/deSugar/DsExpr.lhs index 2ce9440..71df1b1 100644 --- a/ghc/compiler/deSugar/DsExpr.lhs +++ b/ghc/compiler/deSugar/DsExpr.lhs @@ -4,51 +4,58 @@ \section[DsExpr]{Matching expressions (Exprs)} \begin{code} -module DsExpr ( dsExpr, dsLet ) where +module DsExpr ( dsExpr, dsLExpr, dsLet, dsLit ) where #include "HsVersions.h" -import HsSyn ( failureFreePat, - HsExpr(..), OutPat(..), HsLit(..), ArithSeqInfo(..), - Stmt(..), HsMatchContext(..), HsDoContext(..), - Match(..), HsBinds(..), MonoBinds(..), - mkSimpleMatch, isDoExpr - ) -import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, - TypecheckedStmt, TypecheckedMatchContext - ) -import TcType ( tcSplitAppTy, tcSplitFunTys, tcSplitTyConApp_maybe, tcTyConAppArgs, - isIntegerTy, tcSplitTyConApp, isUnLiftedType, Type ) +import Match ( matchWrapper, matchSimply ) +import MatchLit ( dsLit ) +import DsBinds ( dsHsNestedBinds ) +import DsGRHSs ( dsGuarded ) +import DsListComp ( dsListComp, dsPArrComp ) +import DsUtils ( mkErrorAppDs, mkStringExpr, mkConsExpr, mkNilExpr, + mkCoreTupTy, selectSimpleMatchVarL, + dsReboundNames, lookupReboundName ) +import DsArrows ( dsProcExpr ) +import DsMonad + +#ifdef GHCI + -- Template Haskell stuff iff bootstrapped +import DsMeta ( dsBracket ) +#endif + +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 +-- So WATCH OUT; check each use of split*Ty functions. +-- Sigh. This is a pain. + +import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppTyCon, tcTyConAppArgs, + tcTyConAppArgs, isUnLiftedType, Type, mkAppTy, tcEqType ) +import Type ( funArgTy, splitFunTys, isUnboxedTupleType, mkFunTy ) import CoreSyn import CoreUtils ( exprType, mkIfThenElse, bindNonRec ) -import DsMonad -import DsBinds ( dsMonoBinds, AutoScc(..) ) -import DsGRHSs ( dsGuarded ) -import DsCCall ( dsCCall, resultWrapper ) -import DsListComp ( dsListComp ) -import DsUtils ( mkErrorAppDs, mkDsLets, mkStringLit, mkStringLitFS, - mkConsExpr, mkNilExpr, mkIntegerLit - ) -import Match ( matchWrapper, matchSimply ) - -import FieldLabel ( FieldLabel, fieldLabelTyCon ) import CostCentre ( mkUserCC ) -import Id ( Id, idType, recordSelectorFieldLabel ) +import Id ( Id, idType, idName ) import PrelInfo ( rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID ) import DataCon ( DataCon, dataConWrapId, dataConFieldLabels, dataConInstOrigArgTys ) -import DataCon ( isExistentialDataCon ) -import Literal ( Literal(..) ) -import TyCon ( tyConDataCons ) -import TysWiredIn ( tupleCon, listTyCon, charDataCon, intDataCon ) -import BasicTypes ( RecFlag(..), Boxity(..) ) -import Maybes ( maybeToBool ) -import PrelNames ( hasKey, ratioTyConKey ) +import DataCon ( isVanillaDataCon ) +import Name ( Name ) +import TyCon ( FieldLabel, tyConDataCons ) +import TysWiredIn ( tupleCon ) +import BasicTypes ( RecFlag(..), Boxity(..), ipNameName ) +import PrelNames ( toPName, + returnMName, bindMName, thenMName, failMName, + mfixName ) +import SrcLoc ( Located(..), unLoc, getLoc, noLoc ) import Util ( zipEqual, zipWithEqual ) +import Bag ( bagToList ) import Outputable - -import Ratio ( numerator, denominator ) +import FastString \end{code} @@ -70,41 +77,70 @@ 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 (MonoBind (AbsBinds [] [] binder_triples inlines - (PatMonoBind pat grhss loc)) sigs is_rec) body - | or [isUnLiftedType (idType g) | (_, g, l) <- binder_triples] +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}) - putSrcLocDs loc $ - dsGuarded grhss `thenDs` \ rhs -> + -- 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.) let - body' = foldr bind body binder_triples - bind (tyvars, g, l) body = ASSERT( null tyvars ) - bindNonRec g (Var l) 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)) in - mkErrorAppDs iRREFUT_PAT_ERROR_ID result_ty (showSDoc (ppr pat)) - `thenDs` \ error_expr -> - matchSimply rhs PatBindRhs pat body' error_expr - where - result_ty = exprType body + 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) + + [L loc (PatBind pat grhss ty)] + -> putSrcSpanDs loc $ + dsGuarded grhss ty `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) -- 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} +dsBindGroup body (HsBindGroup binds sigs is_rec) + = dsHsNestedBinds binds `thenDs` \ prs -> + returnDs (Let (Rec prs) body) + -- Use a Rec regardless of is_rec. + -- 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. + -- 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} %************************************************************************ %* * @@ -113,20 +149,25 @@ 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 :: HsExpr Id -> DsM CoreExpr -dsExpr (HsVar var) = returnDs (Var var) -dsExpr (HsIPVar var) = returnDs (Var var) -dsExpr (HsLit lit) = dsLit lit +dsExpr (HsPar e) = dsLExpr e +dsExpr (ExprWithTySigOut e _) = dsLExpr e +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 LambdaExpr [a_Match] `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 -> + = dsLExpr fun `thenDs` \ core_fun -> + dsLExpr arg `thenDs` \ core_arg -> returnDs (core_fun `App` core_arg) \end{code} @@ -153,109 +194,96 @@ 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:_, _) = tcSplitFunTys (exprType core_op) + (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:_, _) = tcSplitFunTys (exprType core_op) + (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) --- 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 -> +-- 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; they can't appear nested +dsExpr (HsCase discrim matches@(MatchGroup _ ty)) + | isUnboxedTupleType (funArgTy ty) + = 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)) - where - ubx_tuple_match (Match _ [TuplePat ps Unboxed] _ _) = True - ubx_tuple_match _ = False + Case (Var x) bndr ty alts | x == discrim_var -> + returnDs (Case core_discrim bndr ty alts) + _ -> panic ("dsLExpr: tuple pattern:\n" ++ showSDoc (ppr matching_code)) -dsExpr (HsCase discrim matches src_loc) - = putSrcLocDs src_loc $ - dsExpr discrim `thenDs` \ core_discrim -> - matchWrapper CaseAlt matches `thenDs` \ ([discrim_var], matching_code) -> +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) - = 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) = -- Special case for list comprehensions - putSrcLocDs src_loc $ dsListComp stmts elt_ty + where + [elt_ty] = tcTyConAppArgs result_ty - | otherwise - = putSrcLocDs src_loc $ - dsDo do_or_lc stmts return_id then_id fail_id result_ty +dsExpr (HsDo do_or_lc stmts ids result_ty) + | isDoExpr do_or_lc + = dsDo do_or_lc stmts ids result_ty + +dsExpr (HsDo PArrComp stmts _ result_ty) + = -- Special case for array comprehensions + dsPArrComp (map unLoc stmts) elt_ty where - maybe_list_comp - = case (do_or_lc, tcSplitTyConApp_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 interpretation of ExprStmt depends on what sort of thing - -- it is. - - Just elt_ty = maybe_list_comp - -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 -> + [elt_ty] = tcTyConAppArgs result_ty + +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} @@ -265,11 +293,11 @@ 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} @@ -278,42 +306,75 @@ 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 (x:xs) = dsLExpr x `thenDs` \ core_x -> go xs `thenDs` \ core_xs -> 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 -> + = 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)) + = dsLExpr expr `thenDs` \ expr2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr two `thenDs` \ two2 -> + returnDs (mkApps expr2 [from2, two2]) + +dsExpr (PArrSeqOut expr (FromThenTo from thn two)) + = 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 _) + = 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 @@ -339,15 +400,16 @@ 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, - lbl == recordSelectorFieldLabel sel_id] of + mk_arg (arg_ty, lbl) -- Selector id has the field label as its name + = case [rhs | (L _ sel_id, rhs) <- rbinds, lbl == idName 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 "" @@ -355,8 +417,8 @@ 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) @@ -384,64 +446,64 @@ might do some argument-evaluation first; and may have to throw away some dictionaries. \begin{code} -dsExpr (RecordUpdOut record_expr record_out_ty dicts []) - = dsExpr record_expr +dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty []) + = dsLExpr record_expr -dsExpr (RecordUpdOut record_expr record_out_ty dicts rbinds) - = getSrcLocDs `thenDs` \ src_loc -> - dsExpr record_expr `thenDs` \ record_expr' -> +dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) + = dsLExpr 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 = tcTyConAppArgs record_in_ty - out_inst_tys = tcTyConAppArgs record_out_ty + in_inst_tys = tcTyConAppArgs record_in_ty -- Newtype opaque + out_inst_tys = tcTyConAppArgs record_out_ty -- Newtype opaque + in_out_ty = mkFunTy record_in_ty record_out_ty mk_val_arg field old_arg_id - = case [rhs | (sel_id, rhs, _) <- rbinds, - field == recordSelectorFieldLabel sel_id] of + = case [rhs | (L _ sel_id, rhs) <- rbinds, field == idName 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 -> -- This call to dataConArgTys won't work for existentials + -- but existentials don't have record types anyway 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) - val_args + rhs = foldl (\a b -> nlHsApp a b) + (noLoc $ TyApp (nlHsVar (dataConWrapId con)) + out_inst_tys) + val_args in - returnDs (mkSimpleMatch [ConPat con record_in_ty [] [] (map VarPat arg_ids)] - rhs - (Just record_out_ty) - src_loc) + returnDs (mkSimpleMatch [noLoc $ ConPatOut (noLoc con) [] [] emptyLHsBinds + (PrefixCon (map nlVarPat arg_ids)) record_in_ty] + rhs) in -- Record stuff doesn't work for existentials - ASSERT( all (not . isExistentialDataCon) data_cons ) + -- The type checker checks for this, but we need + -- worry only about the constructors that are to be updated + ASSERT2( all isVanillaDataCon 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 RecUpd alts `thenDs` \ ([discrim_var], matching_code) -> + mappM mk_alt cons_to_upd `thenDs` \ alts -> + matchWrapper RecUpd (MatchGroup alts in_out_ty) `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 = [ idName sel_id | (L _ sel_id,_) <- rbinds] - -- Get the type constructor from the first field label, + -- Get the type constructor from the record_in_ty -- 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) + tycon = tcTyConAppTyCon record_in_ty data_cons = tyConDataCons tycon cons_to_upd = filter has_all_fields data_cons @@ -461,160 +523,174 @@ dsExpr (RecordUpdOut record_expr record_out_ty dicts 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} +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 (HsSpliceE s) = pprPanic "dsExpr:splice" (ppr s) +#endif + +-- Arrow notation extension +dsExpr (HsProc pat cmd) = dsProcExpr pat cmd +\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} %-------------------------------------------------------------------- -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 :: HsDoContext - -> [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) +dsDo :: HsStmtContext Name + -> [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 return_id then_id fail_id result_ty - = let - (_, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b) - is_do = case do_or_lc of - DoExpr -> True - ListComp -> False +dsDo do_or_lc stmts ids result_ty + = dsReboundNames ids `thenDs` \ (meth_binds, ds_meths) -> + let + 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) - -- For ExprStmt, see the comments near HsExpr.HsStmt about + -- For ExprStmt, see the comments near HsExpr.Stmt about -- exactly what ExprStmts mean! -- - -- In dsDo we can only see DoStmt and ListComp (no gaurds) + -- 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 locn : stmts) - | is_do -- Do expression - = do_expr expr locn `thenDs` \ expr2 -> - go stmts `thenDs` \ rest -> - let - (_, a_ty) = tcSplitAppTy (exprType expr2) -- Must be of form (m a) - in - newSysLocalDs a_ty `thenDs` \ ignored_result_id -> - returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2, - Lam ignored_result_id 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 -> + mkStringExpr (mk_msg (getLoc pat)) `thenDs` \ core_msg -> let - (_, a_ty) = tcSplitAppTy (exprType expr2) -- Must be of form (m a) - fail_expr = HsApp (TyApp (HsVar fail_id) [b_ty]) - (HsLit (HsString (_PK_ msg))) - 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 - | 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 (DoCtxt do_or_lc) the_matches `thenDs` \ (binders, matching_code) -> - returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2, - mkLams binders matching_code]) + selectSimpleMatchVarL 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 (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} - -%************************************************************************ -%* * -\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 tcSplitTyConApp ty of - (tycon, [i_ty]) -> ASSERT(isIntegerTy i_ty && tycon `hasKey` ratioTyConKey) - (head (tyConDataCons tycon), i_ty) +dsRecStmt :: Type -- Monad type constructor :: * -> * + -> [(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 rec_vars > 0 ) + ASSERT( length rec_vars == length rec_rets ) + BindStmt (mk_tup_pat later_pats) mfix_app + where + -- Remove any vars from later_vars that already in rec_vars + -- NB that having the same name is not enough; they must have + -- the same type. See Note [RecStmt] in HsExpr. + trimmed_laters = filter not_in_rec later_vars + not_in_rec lv = null [ v | let lv_type = idType lv + , v <- rec_vars + , v == lv + , lv_type `tcEqType` idType v ] + + mfix_app = nlHsApp (noLoc $ TyApp (nlHsVar mfix_id) [tup_ty]) mfix_arg + mfix_arg = noLoc $ HsLam (MatchGroup [mkSimpleMatch [mfix_pat] body] + (mkFunTy tup_ty body_ty)) + + -- The rec_tup_pat must bind the rec_vars only; remember that the + -- trimmed_laters may share the same Names + -- Meanwhile, the later_pats must bind the later_vars + rec_tup_pats = map mk_wild_pat trimmed_laters ++ map nlVarPat rec_vars + later_pats = map nlVarPat trimmed_laters ++ map mk_later_pat rec_vars + rets = map nlHsVar trimmed_laters ++ rec_rets + + mfix_pat = noLoc $ LazyPat $ mk_tup_pat rec_tup_pats + body = noLoc $ HsDo DoExpr (stmts ++ [return_stmt]) + [(n, HsVar id) | (n,id) <- ds_meths] -- A bit of a hack + body_ty + body_ty = mkAppTy m_ty tup_ty + tup_ty = mkCoreTupTy (map idType (trimmed_laters ++ rec_vars)) + -- mkCoreTupTy deals with singleton case + + 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]) + (mk_ret_tup rets) + + mk_wild_pat :: Id -> LPat Id + mk_wild_pat v = noLoc $ WildPat $ idType v + + mk_later_pat :: Id -> LPat Id + mk_later_pat v | v `elem` trimmed_laters = mk_wild_pat v + | otherwise = nlVarPat v + + mk_tup_pat :: [LPat Id] -> LPat Id + mk_tup_pat [p] = p + mk_tup_pat ps = noLoc $ TuplePat ps Boxed + + mk_ret_tup :: [LHsExpr Id] -> LHsExpr Id + mk_ret_tup [r] = r + mk_ret_tup rs = noLoc $ ExplicitTuple rs Boxed \end{code} - - -