X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsExpr.lhs;h=79303efa86ca3f5fe29bf643a9b5cf176175216f;hb=5d3051c66796dcf884b052f9e4afc3ed19b9f514;hp=bc8a1f58f0041c3b2cdd5ce8c7f91f3bf10e0f01;hpb=9af77fa423926fbda946b31e174173d0ec5ebac8;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsExpr.lhs b/ghc/compiler/deSugar/DsExpr.lhs index bc8a1f5..79303ef 100644 --- a/ghc/compiler/deSugar/DsExpr.lhs +++ b/ghc/compiler/deSugar/DsExpr.lhs @@ -4,18 +4,19 @@ \section[DsExpr]{Matching expressions (Exprs)} \begin{code} -module DsExpr ( dsExpr, dsLet, dsLit ) where +module DsExpr ( dsExpr, dsLExpr, dsLocalBinds, dsValBinds, dsLit ) where #include "HsVersions.h" - -import Match ( matchWrapper, matchSimply ) -import MatchLit ( dsLit ) -import DsBinds ( dsMonoBinds, AutoScc(..) ) +import Match ( matchWrapper, matchSimply, matchSinglePat ) +import MatchLit ( dsLit, dsOverLit ) +import DsBinds ( dsLHsBinds, dsCoercion ) import DsGRHSs ( dsGuarded ) -import DsCCall ( dsCCall ) import DsListComp ( dsListComp, dsPArrComp ) -import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr) +import DsUtils ( mkErrorAppDs, mkStringExpr, mkConsExpr, mkNilExpr, + extractMatchResult, cantFailMatchResult, matchCanFail, + mkCoreTupTy, selectSimpleMatchVarL, lookupEvidence ) +import DsArrows ( dsProcExpr ) import DsMonad #ifdef GHCI @@ -23,36 +24,34 @@ import DsMonad import DsMeta ( dsBracket ) #endif -import HsSyn ( failureFreePat, - HsExpr(..), Pat(..), HsLit(..), ArithSeqInfo(..), - Stmt(..), HsMatchContext(..), HsDoContext(..), - Match(..), HsBinds(..), MonoBinds(..), HsConDetails(..), - mkSimpleMatch - ) -import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, hsPatType ) +import HsSyn +import TcHsSyn ( hsPatType, mkVanillaTuplePat ) -- 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 ) -import Type ( splitFunTys ) +import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppTyCon, + tcTyConAppArgs, isUnLiftedType, Type, mkAppTy ) +import Type ( funArgTy, splitFunTys, isUnboxedTupleType, mkFunTy ) import CoreSyn import CoreUtils ( exprType, mkIfThenElse, bindNonRec ) -import FieldLabel ( FieldLabel, fieldLabelTyCon ) import CostCentre ( mkUserCC ) -import Id ( Id, idType, recordSelectorFieldLabel ) +import Id ( Id, idType, idName, idDataCon ) import PrelInfo ( rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID ) import DataCon ( DataCon, dataConWrapId, dataConFieldLabels, dataConInstOrigArgTys ) -import DataCon ( isExistentialDataCon ) -import TyCon ( tyConDataCons ) +import DataCon ( isVanillaDataCon ) +import TyCon ( FieldLabel, tyConDataCons ) import TysWiredIn ( tupleCon ) import BasicTypes ( RecFlag(..), Boxity(..), ipNameName ) -import PrelNames ( toPName ) +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} @@ -60,73 +59,80 @@ import FastString %************************************************************************ %* * -\subsection{dsLet} + dsLocalBinds, dsValBinds %* * %************************************************************************ -@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 -\begin{verbatim} - C x# = e -\end{verbatim} -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 +dsLocalBinds :: HsLocalBinds Id -> CoreExpr -> DsM CoreExpr +dsLocalBinds EmptyLocalBinds body = return body +dsLocalBinds (HsValBinds binds) body = dsValBinds binds body +dsLocalBinds (HsIPBinds binds) body = dsIPBinds binds body + +------------------------- +dsValBinds :: HsValBinds Id -> CoreExpr -> DsM CoreExpr +dsValBinds (ValBindsOut binds _) body = foldrDs ds_val_bind body binds + +------------------------- +dsIPBinds (IPBinds ip_binds dict_binds) body + = do { prs <- dsLHsBinds dict_binds + ; let inner = foldr (\(x,r) e -> Let (NonRec x r) e) body prs + ; foldrDs ds_ip_bind inner ip_binds } + where + ds_ip_bind (L _ (IPBind n e)) body + = dsLExpr e `thenDs` \ e' -> + returnDs (Let (NonRec (ipNameName n) e') body) -dsLet (ThenBinds b1 b2) body - = dsLet b2 body `thenDs` \ body' -> - dsLet b1 body' - +------------------------- +ds_val_bind :: (RecFlag, LHsBinds Id) -> CoreExpr -> DsM CoreExpr -- 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] - = ASSERT (case is_rec of {NonRecursive -> True; other -> False}) - -- Unlifted bindings are always non-recursive - -- and are always a Fun or Pat monobind - -- +-- Silently ignore INLINE and SPECIALISE pragmas... +ds_val_bind (NonRecursive, hsbinds) body + | [L _ (AbsBinds [] [] exports binds)] <- bagToList hsbinds, + (L loc bind : null_binds) <- bagToList binds, + or [isUnLiftedType (idType g) | (_, g, _, _) <- exports] + || isBangHsBind bind + = let + body_w_exports = foldr bind_export body exports + bind_export (tvs, g, l, _) body = ASSERT( null tvs ) + bindNonRec g (Var l) body + in + ASSERT (null null_binds) + -- Non-recursive, non-overloaded bindings only come in ones -- 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 fun) matches `thenDs` \ (args, rhs) -> + putSrcSpanDs loc $ + case bind of + FunBind { fun_id = L _ fun, fun_matches = matches, fun_co_fn = co_fn } + -> matchWrapper (FunRhs (idName fun)) matches `thenDs` \ (args, rhs) -> ASSERT( null args ) -- Functions aren't lifted + ASSERT( isIdCoercion co_fn ) returnDs (bindNonRec fun rhs body_w_exports) - PatMonoBind pat grhss loc - -> putSrcLocDs loc $ - dsGuarded grhss `thenDs` \ rhs -> + PatBind {pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = 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 $$ ppr body) + other -> pprPanic "dsLet: unlifted" (pprLHsBinds hsbinds $$ 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 + 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 -> - returnDs (Let (Rec prs) body) +-- Ordinary case for bindings; none should be unlifted +ds_val_bind (is_rec, binds) body + = do { prs <- dsLHsBinds binds + ; ASSERT( not (any (isUnLiftedType . idType . fst) prs) ) + case prs of + [] -> return body + other -> return (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. @@ -144,21 +150,30 @@ 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 (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 :: HsExpr Id -> DsM CoreExpr + +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 +dsExpr (HsOverLit lit) = dsOverLit lit + +dsExpr (NegApp expr neg_expr) + = do { core_expr <- dsLExpr expr + ; core_neg <- dsExpr neg_expr + ; return (core_neg `App` core_expr) } 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} @@ -185,111 +200,113 @@ 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) --- 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 +-- The idea is that +-- case e of (# p1, p2 #) -> rhs +-- should desugar to +-- case e of (# x1, x2 #) -> ... match p1, p2 ... +-- NOT +-- let x = e in case x of .... +-- +-- But there may be a big +-- let fail = ... in case e of ... +-- wrapping the whole case, which complicates matters slightly +-- It all seems a bit fragile. Test is dsrun013. + +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 + let + scrungle (Case (Var x) bndr ty alts) + | x == discrim_var = Case core_discrim bndr ty alts + scrungle (Let binds body) = Let binds (scrungle body) + scrungle other = panic ("dsLExpr: tuple pattern:\n" ++ showSDoc (ppr other)) + in + returnDs (scrungle 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' -> - 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) + = dsLExpr body `thenDs` \ body' -> + dsLocalBinds binds 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 body result_ty) = -- Special case for list comprehensions - putSrcLocDs src_loc $ - dsListComp stmts elt_ty + dsListComp stmts body elt_ty where - (_, [elt_ty]) = tcSplitTyConApp result_ty + [elt_ty] = tcTyConAppArgs result_ty + +dsExpr (HsDo DoExpr stmts body result_ty) + = dsDo stmts body result_ty -dsExpr (HsDo DoExpr stmts ids result_ty src_loc) - = putSrcLocDs src_loc $ - dsDo DoExpr stmts ids result_ty +dsExpr (HsDo (MDoExpr tbl) stmts body result_ty) + = dsMDo tbl stmts body result_ty -dsExpr (HsDo PArrComp stmts _ result_ty src_loc) +dsExpr (HsDo PArrComp stmts body result_ty) = -- Special case for array comprehensions - putSrcLocDs src_loc $ - dsPArrComp stmts elt_ty + dsPArrComp (map unLoc stmts) body elt_ty where - (_, [elt_ty]) = tcSplitTyConApp result_ty + [elt_ty] = tcTyConAppArgs 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} @@ -299,11 +316,11 @@ 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} @@ -316,14 +333,14 @@ 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 +-- * 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 @@ -336,48 +353,48 @@ 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 (ArithSeq expr (From from)) = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> + dsLExpr from `thenDs` \ from2 -> returnDs (App expr2 from2) -dsExpr (ArithSeqOut expr (FromTo from two)) +dsExpr (ArithSeq expr (FromTo from two)) = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> - dsExpr two `thenDs` \ two2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr two `thenDs` \ two2 -> returnDs (mkApps expr2 [from2, two2]) -dsExpr (ArithSeqOut expr (FromThen from thn)) +dsExpr (ArithSeq expr (FromThen from thn)) = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> - dsExpr thn `thenDs` \ thn2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr thn `thenDs` \ thn2 -> returnDs (mkApps expr2 [from2, thn2]) -dsExpr (ArithSeqOut expr (FromThenTo from thn two)) +dsExpr (ArithSeq expr (FromThenTo from thn two)) = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> - dsExpr thn `thenDs` \ thn2 -> - dsExpr two `thenDs` \ two2 -> + 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 (PArrSeq expr (FromTo from two)) = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> - dsExpr two `thenDs` \ two2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr two `thenDs` \ two2 -> returnDs (mkApps expr2 [from2, two2]) -dsExpr (PArrSeqOut expr (FromThenTo from thn two)) +dsExpr (PArrSeq expr (FromThenTo from thn two)) = dsExpr expr `thenDs` \ expr2 -> - dsExpr from `thenDs` \ from2 -> - dsExpr thn `thenDs` \ thn2 -> - dsExpr two `thenDs` \ two2 -> + dsLExpr from `thenDs` \ from2 -> + dsLExpr thn `thenDs` \ thn2 -> + dsLExpr two `thenDs` \ two2 -> returnDs (mkApps expr2 [from2, thn2, two2]) -dsExpr (PArrSeqOut expr _) +dsExpr (PArrSeq 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 @@ -405,27 +422,27 @@ We also handle @C{}@ as valid construction syntax for an unlabelled constructor @C@, setting all of @C@'s fields to bottom. \begin{code} -dsExpr (RecordConOut data_con con_expr rbinds) +dsExpr (RecordCon (L _ data_con_id) con_expr rbinds) = dsExpr 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 "" - labels = dataConFieldLabels data_con + labels = dataConFieldLabels (idDataCon data_con_id) + -- The data_con_id is guaranteed to be the wrapper id of the constructor 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) @@ -453,12 +470,11 @@ might do some argument-evaluation first; and may have to throw away some dictionaries. \begin{code} -dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty []) - = dsExpr record_expr +dsExpr (RecordUpd record_expr [] record_in_ty record_out_ty) + = 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' -> +dsExpr expr@(RecordUpd record_expr rbinds record_in_ty record_out_ty) + = dsLExpr record_expr `thenDs` \ record_expr' -> -- Desugar the rbinds, and generate let-bindings if -- necessary so that we don't lose sharing @@ -466,50 +482,52 @@ dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) let 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 + -- This call to dataConInstOrigArgTys 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 (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 [] []] - rhs - 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 -- 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 ) + 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 @@ -529,14 +547,16 @@ 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) + +dsExpr (HsCoerce co_fn e) = dsCoercion co_fn (dsExpr e) \end{code} Here is where we desugar the Template Haskell brackets and escapes @@ -546,9 +566,11 @@ 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} @@ -557,84 +579,157 @@ dsExpr (HsSplice n e) = pprPanic "dsExpr:splice" (ppr e) #ifdef DEBUG -- HsSyn constructs that just shouldn't be here: 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,fail,>>=,>>] - -> Type -- Element type; the whole expression has type (m t) +dsDo :: [LStmt Id] + -> LHsExpr Id + -> Type -- Type of the whole expression -> DsM CoreExpr -dsDo do_or_lc stmts ids@[return_id, fail_id, bind_id, then_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 - _ -> False - - -- 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 (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)) +dsDo stmts body result_ty + = go (map unLoc stmts) + where + go [] = dsLExpr body - go (LetStmt binds : stmts ) - = go stmts `thenDs` \ rest -> - dsLet binds rest - - go (BindStmt pat expr locn : stmts) - = putSrcLocDs locn $ - dsExpr expr `thenDs` \ expr2 -> - let - 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 (DoCtxt 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]) - in - go stmts + go (ExprStmt rhs then_expr _ : stmts) + = do { rhs2 <- dsLExpr rhs + ; then_expr2 <- dsExpr then_expr + ; rest <- go stmts + ; returnDs (mkApps then_expr2 [rhs2, rest]) } + + go (LetStmt binds : stmts) + = do { rest <- go stmts + ; dsLocalBinds binds rest } + + go (BindStmt pat rhs bind_op fail_op : stmts) + = do { body <- go stmts + ; var <- selectSimpleMatchVarL pat + ; match <- matchSinglePat (Var var) (StmtCtxt DoExpr) pat + result_ty (cantFailMatchResult body) + ; match_code <- handle_failure pat match fail_op + ; rhs' <- dsLExpr rhs + ; bind_op' <- dsExpr bind_op + ; returnDs (mkApps bind_op' [rhs', Lam var match_code]) } + + -- In a do expression, pattern-match failure just calls + -- the monadic 'fail' rather than throwing an exception + handle_failure pat match fail_op + | matchCanFail match + = do { fail_op' <- dsExpr fail_op + ; fail_msg <- mkStringExpr (mk_fail_msg pat) + ; extractMatchResult match (App fail_op' fail_msg) } + | otherwise + = extractMatchResult match (error "It can't fail") + +mk_fail_msg pat = "Pattern match failure in do expression at " ++ + showSDoc (ppr (getLoc pat)) +\end{code} +Translation for RecStmt's: +----------------------------- +We turn (RecStmt [v1,..vn] stmts) into: + + (v1,..,vn) <- mfix (\~(v1,..vn). do stmts + return (v1,..vn)) + +\begin{code} +dsMDo :: PostTcTable + -> [LStmt Id] + -> LHsExpr Id + -> Type -- Type of the whole expression + -> DsM CoreExpr + +dsMDo tbl stmts body result_ty + = go (map unLoc stmts) where - do_expr expr locn = putSrcLocDs locn (dsExpr expr) + (m_ty, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b) + mfix_id = lookupEvidence tbl mfixName + return_id = lookupEvidence tbl returnMName + bind_id = lookupEvidence tbl bindMName + then_id = lookupEvidence tbl thenMName + fail_id = lookupEvidence tbl failMName + ctxt = MDoExpr tbl + + go [] = dsLExpr body + + go (LetStmt binds : stmts) + = do { rest <- go stmts + ; dsLocalBinds binds rest } + + go (ExprStmt rhs _ rhs_ty : stmts) + = do { rhs2 <- dsLExpr rhs + ; rest <- go stmts + ; returnDs (mkApps (Var then_id) [Type rhs_ty, Type b_ty, rhs2, rest]) } + + go (BindStmt pat rhs _ _ : stmts) + = do { body <- go stmts + ; var <- selectSimpleMatchVarL pat + ; match <- matchSinglePat (Var var) (StmtCtxt ctxt) pat + result_ty (cantFailMatchResult body) + ; fail_msg <- mkStringExpr (mk_fail_msg pat) + ; let fail_expr = mkApps (Var fail_id) [Type b_ty, fail_msg] + ; match_code <- extractMatchResult match fail_expr + + ; rhs' <- dsLExpr rhs + ; returnDs (mkApps (Var bind_id) [Type (hsPatType pat), Type b_ty, + rhs', Lam var match_code]) } + + go (RecStmt rec_stmts later_ids rec_ids rec_rets binds : stmts) + = ASSERT( length rec_ids > 0 ) + ASSERT( length rec_ids == length rec_rets ) + go (new_bind_stmt : let_stmt : stmts) + where + new_bind_stmt = mkBindStmt (mk_tup_pat later_pats) mfix_app + let_stmt = LetStmt (HsValBinds (ValBindsOut [(Recursive, binds)] [])) + + + -- Remove the later_ids that appear (without fancy coercions) + -- in rec_rets, because there's no need to knot-tie them separately + -- See Note [RecStmt] in HsExpr + later_ids' = filter (`notElem` mono_rec_ids) later_ids + mono_rec_ids = [ id | HsVar id <- rec_rets ] + + 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_ids 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 later_ids' ++ map nlVarPat rec_ids + later_pats = map nlVarPat later_ids' ++ map mk_later_pat rec_ids + rets = map nlHsVar later_ids' ++ map noLoc rec_rets + + mfix_pat = noLoc $ LazyPat $ mk_tup_pat rec_tup_pats + body = noLoc $ HsDo ctxt rec_stmts return_app body_ty + body_ty = mkAppTy m_ty tup_ty + tup_ty = mkCoreTupTy (map idType (later_ids' ++ rec_ids)) + -- mkCoreTupTy deals with singleton case + + 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` later_ids' = mk_wild_pat v + | otherwise = nlVarPat v + + mk_tup_pat :: [LPat Id] -> LPat Id + mk_tup_pat [p] = p + mk_tup_pat ps = noLoc $ mkVanillaTuplePat ps Boxed + + mk_ret_tup :: [LHsExpr Id] -> LHsExpr Id + mk_ret_tup [r] = r + mk_ret_tup rs = noLoc $ ExplicitTuple rs Boxed \end{code}