X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsExpr.lhs;h=0350843905f89f1f29320bcce3c97066dce532c5;hb=3721dd37a707d2aacb5cac814410a78096e28a2c;hp=0afd0bc83992a2f887963c0f2382eba09201c026;hpb=8f7ac3fe40d3d55743b824deab655d0797a1c55f;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsExpr.lhs b/ghc/compiler/deSugar/DsExpr.lhs index 0afd0bc..0350843 100644 --- a/ghc/compiler/deSugar/DsExpr.lhs +++ b/ghc/compiler/deSugar/DsExpr.lhs @@ -1,195 +1,175 @@ % -% (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, dsLExpr, dsLet, dsLit ) where + #include "HsVersions.h" -module DsExpr ( dsExpr ) where -IMP_Ubiq() -IMPORT_DELOOPER(DsLoop) -- partly to get dsBinds, partly to chk dsExpr +import Match ( matchWrapper, matchSimply ) +import MatchLit ( dsLit ) +import DsBinds ( dsHsBinds, AutoScc(..) ) +import DsGRHSs ( dsGuarded ) +import DsListComp ( dsListComp, dsPArrComp ) +import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr, + mkCoreTupTy, selectMatchVarL, + 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 HsSyn ( failureFreePat, - HsExpr(..), OutPat(..), HsLit(..), ArithSeqInfo(..), - Stmt(..), Match(..), Qualifier, HsBinds, HsType, - GRHSsAndBinds - ) -import TcHsSyn ( SYN_IE(TypecheckedHsExpr), SYN_IE(TypecheckedHsBinds), - SYN_IE(TypecheckedRecordBinds), SYN_IE(TypecheckedPat), - SYN_IE(TypecheckedStmt) - ) +import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppArgs, + tcSplitTyConApp, isUnLiftedType, Type, + mkAppTy ) +import Type ( splitFunTys ) import CoreSyn +import CoreUtils ( exprType, mkIfThenElse, bindNonRec ) -import DsMonad -import DsCCall ( dsCCall ) -import DsHsSyn ( outPatType ) -import DsListComp ( dsListComp ) -import DsUtils ( mkAppDs, mkConDs, mkPrimDs, dsExprToAtom, - mkErrorAppDs, showForErr, EquationInfo, - MatchResult, SYN_IE(DsCoreArg) - ) -import Match ( matchWrapper ) - -import CoreUtils ( coreExprType, substCoreExpr, argToExpr, - mkCoreIfThenElse, unTagBinders ) +import FieldLabel ( FieldLabel, fieldLabelTyCon ) import CostCentre ( mkUserCC ) -import FieldLabel ( fieldLabelType, FieldLabel ) -import Id ( idType, nullIdEnv, addOneToIdEnv, - dataConArgTys, dataConFieldLabels, - recordSelectorFieldLabel - ) -import Literal ( mkMachInt, Literal(..) ) -import Name ( Name{--O only-} ) -import PprStyle ( PprStyle(..) ) -import PprType ( GenType ) -import PrelVals ( rEC_CON_ERROR_ID, rEC_UPD_ERROR_ID, voidId ) -import Pretty ( ppShow, ppBesides, ppPStr, ppStr ) -import TyCon ( isDataTyCon, isNewTyCon ) -import Type ( splitSigmaTy, splitFunTy, typePrimRep, - getAppDataTyConExpandingDicts, getAppTyCon, applyTy, - maybeBoxedPrimType - ) -import TysPrim ( voidTy ) -import TysWiredIn ( mkTupleTy, tupleCon, nilDataCon, consDataCon, - charDataCon, charTy - ) -import TyVar ( nullTyVarEnv, addOneToTyVarEnv, GenTyVar{-instance Eq-} ) -import Usage ( SYN_IE(UVar) ) -import Util ( zipEqual, pprError, panic, assertPanic ) - -mk_nil_con ty = mkCon nilDataCon [] [ty] [] -- micro utility... +import Id ( Id, idType, idName, recordSelectorFieldLabel ) +import PrelInfo ( rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID ) +import DataCon ( DataCon, dataConWrapId, dataConFieldLabels, dataConInstOrigArgTys ) +import DataCon ( isExistentialDataCon ) +import Name ( Name ) +import TyCon ( 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 FastString \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[DsExpr-vars-and-cons]{Variables and constructors} +\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 +\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} -dsExpr :: TypecheckedHsExpr -> DsM CoreExpr +dsLet :: [HsBindGroup Id] -> CoreExpr -> DsM CoreExpr +dsLet groups body = foldlDs dsBindGroup body (reverse groups) -dsExpr e@(HsVar var) = dsApp e [] -\end{code} +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) + +-- 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... +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 + -- + -- 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_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) + + [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) + +-- Ordinary case for bindings +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 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} %************************************************************************ %* * -\subsection[DsExpr-literals]{Literals} +\subsection[DsExpr-vars-and-cons]{Variables, constructors, 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.] -Otherwise, we punt, putting in a "NoRep" Core literal (where the -representation decisions are delayed)... - -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) - - | _LENGTH_ s == 1 - = let - the_char = mkCon charDataCon [] [] [LitArg (MachChar (_HEAD_ s))] - the_nil = mk_nil_con charTy - in - mkConDs consDataCon [TyArg charTy, VarArg the_char, VarArg the_nil] - --- "_" => build (\ c n -> c 'c' n) -- LATER - --- "str" ==> build (\ c n -> foldr charTy T c n "str") - -{- LATER: -dsExpr (HsLitOut (HsString str) _) - = newTyVarsDs [alphaTyVar] `thenDs` \ [new_tyvar] -> - let - new_ty = mkTyVarTy new_tyvar - in - newSysLocalsDs [ - charTy `mkFunTy` (new_ty `mkFunTy` new_ty), - new_ty, - mkForallTy [alphaTyVar] - ((charTy `mkFunTy` (alphaTy `mkFunTy` alphaTy)) - `mkFunTy` (alphaTy `mkFunTy` alphaTy)) - ] `thenDs` \ [c,n,g] -> - returnDs (mkBuild charTy new_tyvar c n g ( - foldl App - (CoTyApp (CoTyApp (Var foldrId) charTy) new_ty) *** ensure non-prim type *** - [VarArg c,VarArg n,LitArg (NoRepStr str)])) --} - --- otherwise, leave it as a NoRepStr; --- the Core-to-STG pass will wrap it in an application of "unpackCStringId". - -dsExpr (HsLitOut (HsString str) _) - = returnDs (Lit (NoRepStr str)) - -dsExpr (HsLitOut (HsLitLit s) ty) - = returnDs ( mkCon data_con [] [] [LitArg (MachLitLit s kind)] ) - where - (data_con, kind) - = case (maybeBoxedPrimType ty) of - Just (boxing_data_con, prim_ty) - -> (boxing_data_con, typePrimRep prim_ty) - Nothing - -> pprError "ERROR: ``literal-literal'' not a single-constructor type: " - (ppBesides [ppPStr s, ppStr "; type: ", ppr PprDebug ty]) - -dsExpr (HsLitOut (HsInt i) ty) - = returnDs (Lit (NoRepInteger i ty)) - -dsExpr (HsLitOut (HsFrac r) ty) - = returnDs (Lit (NoRepRational r ty)) +dsLExpr :: LHsExpr Id -> DsM CoreExpr +dsLExpr (L loc e) = putSrcSpanDs loc $ dsExpr e --- others where we know what to do: +dsExpr :: HsExpr Id -> DsM CoreExpr -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) - -dsExpr (HsLitOut (HsFloatPrim f) _) - = returnDs (Lit (MachFloat f)) - -- ToDo: range checking needed! - -dsExpr (HsLitOut (HsDoublePrim d) _) - = returnDs (Lit (MachDouble d)) - -- ToDo: range checking needed! - -dsExpr (HsLitOut (HsChar c) _) - = returnDs ( mkCon charDataCon [] [] [LitArg (MachChar c)] ) - -dsExpr (HsLitOut (HsCharPrim c) _) - = returnDs (Lit (MachChar c)) - -dsExpr (HsLitOut (HsStringPrim s) _) - = returnDs (Lit (MachStr s)) - --- end of literals magic. -- +dsExpr (HsPar x) = dsLExpr x +dsExpr (HsVar var) = returnDs (Var var) +dsExpr (HsIPVar ip) = returnDs (Var (ipNameName ip)) +dsExpr (HsLit lit) = dsLit lit +-- HsOverLit has been gotten rid of by the type checker dsExpr expr@(HsLam a_Match) - = matchWrapper LambdaMatch [a_Match] "lambda" `thenDs` \ (binders, matching_code) -> - returnDs ( mkValLam binders matching_code ) + = matchWrapper LambdaExpr [a_Match] `thenDs` \ (binders, matching_code) -> + returnDs (mkLams binders matching_code) -dsExpr expr@(HsApp e1 e2) = dsApp expr [] -dsExpr expr@(OpApp e1 op e2) = dsApp expr [] +dsExpr expr@(HsApp fun arg) + = dsLExpr fun `thenDs` \ core_fun -> + dsLExpr arg `thenDs` \ core_arg -> + returnDs (core_fun `App` core_arg) \end{code} Operator sections. At first it looks as if we can convert @@ -214,175 +194,250 @@ If \tr{expr} is actually just a variable, say, then the simplifier will sort it out. \begin{code} +dsExpr (OpApp e1 op _ e2) + = dsLExpr op `thenDs` \ core_op -> + -- for the type of y, we need the type of op's 2nd argument + 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 -> - dsExpr expr `thenDs` \ core_expr -> - dsExprToAtom (VarArg core_expr) $ \ y_atom -> - - -- for the type of x, we need the type of op's 2nd argument + = dsLExpr op `thenDs` \ core_op -> + -- for the type of y, we need the type of op's 2nd argument let - x_ty = case (splitSigmaTy (coreExprType core_op)) of { (_, _, tau_ty) -> - case (splitFunTy tau_ty) of { - ((_:arg2_ty:_), _) -> arg2_ty; - _ -> panic "dsExpr:SectionL:arg 2 ty" }} + (x_ty:y_ty:_, _) = splitFunTys (exprType core_op) + -- Must look through an implicit-parameter type; + -- newtype impossible; hence Type.splitFunTys in - newSysLocalDs x_ty `thenDs` \ x_id -> - returnDs (mkValLam [x_id] (core_op `App` y_atom `App` VarArg x_id)) + dsLExpr expr `thenDs` \ x_core -> + newSysLocalDs x_ty `thenDs` \ x_id -> + newSysLocalDs y_ty `thenDs` \ y_id -> --- dsExpr (SectionR op expr) -- \ x -> op x expr -dsExpr (SectionR op expr) - = dsExpr op `thenDs` \ core_op -> - dsExpr expr `thenDs` \ core_expr -> - dsExprToAtom (VarArg core_expr) $ \ y_atom -> + returnDs (bindNonRec x_id x_core $ + Lam y_id (mkApps core_op [Var x_id, Var y_id])) - -- for the type of x, we need the type of op's 1st argument +-- dsLExpr (SectionR op expr) -- \ x -> op x expr +dsExpr (SectionR op expr) + = dsLExpr op `thenDs` \ core_op -> + -- for the type of x, we need the type of op's 2nd argument let - x_ty = case (splitSigmaTy (coreExprType core_op)) of { (_, _, tau_ty) -> - case (splitFunTy tau_ty) of { - ((arg1_ty:_), _) -> arg1_ty; - _ -> panic "dsExpr:SectionR:arg 1 ty" }} + (x_ty:y_ty:_, _) = splitFunTys (exprType core_op) + -- See comment with SectionL in - newSysLocalDs x_ty `thenDs` \ x_id -> - returnDs (mkValLam [x_id] (core_op `App` VarArg x_id `App` y_atom)) + dsLExpr expr `thenDs` \ y_core -> + newSysLocalDs x_ty `thenDs` \ x_id -> + newSysLocalDs y_ty `thenDs` \ y_id -> -dsExpr (CCall label args may_gc is_asm result_ty) - = mapDs dsExpr args `thenDs` \ core_args -> - dsCCall label core_args may_gc is_asm result_ty - -- dsCCall does all the unboxification, etc. + returnDs (bindNonRec y_id y_core $ + Lam x_id (mkApps core_op [Var x_id, Var y_id])) dsExpr (HsSCC cc expr) - = dsExpr expr `thenDs` \ core_expr -> - getModuleAndGroupDs `thenDs` \ (mod_name, group_name) -> - returnDs ( SCC (mkUserCC cc mod_name group_name) core_expr) - -dsExpr expr@(HsCase discrim matches src_loc) - = 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 ) - -dsExpr (ListComp expr quals) - = dsExpr expr `thenDs` \ core_expr -> - dsListComp core_expr quals - -dsExpr (HsLet binds expr) - = dsBinds False binds `thenDs` \ core_binds -> - dsExpr expr `thenDs` \ core_expr -> - returnDs ( mkCoLetsAny core_binds core_expr ) - -dsExpr (HsDoOut stmts then_id zero_id src_loc) - = putSrcLocDs src_loc $ - dsDo then_id zero_id stmts - -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 -> - returnDs (mkCoreIfThenElse core_guard core_then core_else) + = 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) + | all ubx_tuple_match matches + = 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 ("dsLExpr: tuple pattern:\n" ++ showSDoc (ppr matching_code)) + where + ubx_tuple_match (L _ (Match [L _ (TuplePat _ Unboxed)] _ _)) = True + ubx_tuple_match _ = False + +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) + = dsLExpr body `thenDs` \ body' -> + dsLet 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) + = -- Special case for list comprehensions + dsListComp stmts elt_ty + where + (_, [elt_ty]) = tcSplitTyConApp 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 + (_, [elt_ty]) = tcSplitTyConApp 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} -Type lambda and application -~~~~~~~~~~~~~~~~~~~~~~~~~~~ +\noindent +\underline{\bf Type lambda and application} +% ~~~~~~~~~~~~~~~~~~~~~~~~~~~ \begin{code} dsExpr (TyLam tyvars expr) - = dsExpr expr `thenDs` \ core_expr -> - returnDs (mkTyLam tyvars core_expr) + = dsLExpr expr `thenDs` \ core_expr -> + returnDs (mkLams tyvars core_expr) -dsExpr expr@(TyApp e tys) = dsApp expr [] +dsExpr (TyApp expr tys) + = dsLExpr expr `thenDs` \ core_expr -> + returnDs (mkTyApps core_expr tys) \end{code} -Various data construction things -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +\noindent +\underline{\bf Various data construction things} +% ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \begin{code} -dsExpr (ExplicitListOut ty xs) - = case xs of - [] -> returnDs (mk_nil_con ty) - (y:ys) -> - dsExpr y `thenDs` \ core_hd -> - dsExpr (ExplicitListOut ty ys) `thenDs` \ core_tl -> - mkConDs consDataCon [TyArg ty, VarArg core_hd, VarArg core_tl] - -dsExpr (ExplicitTuple expr_list) - = mapDs dsExpr expr_list `thenDs` \ core_exprs -> - mkConDs (tupleCon (length expr_list)) - (map (TyArg . coreExprType) core_exprs ++ map VarArg core_exprs) +dsExpr (ExplicitList ty xs) + = go xs + where + go [] = returnDs (mkNilExpr ty) + 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) + = 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 -> - mkAppDs expr2 [VarArg 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 -> - mkAppDs expr2 [VarArg from2, VarArg 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 -> - mkAppDs expr2 [VarArg from2, VarArg 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 -> - mkAppDs expr2 [VarArg from2, VarArg thn2, VarArg 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} -Record construction and update -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +\noindent +\underline{\bf Record construction and update} +% ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For record construction we do this (assuming T has three arguments) - +\begin{verbatim} T { op2 = e } ==> let err = /\a -> recConErr a T (recConErr t1 "M.lhs/230/op1") e (recConErr t1 "M.lhs/230/op3") - -recConErr then converts its arugment string into a proper message +\end{verbatim} +@recConErr@ then converts its arugment string into a proper message before printing it as - +\begin{verbatim} M.lhs, line 230: missing field op1 was evaluated +\end{verbatim} +We also handle @C{}@ as valid construction syntax for an unlabelled +constructor @C@, setting all of @C@'s fields to bottom. \begin{code} -dsExpr (RecordCon con_expr rbinds) - = dsExpr con_expr `thenDs` \ con_expr' -> +dsExpr (RecordConOut data_con con_expr rbinds) + = dsLExpr con_expr `thenDs` \ con_expr' -> let - con_id = get_con con_expr' - (arg_tys, _) = splitFunTy (coreExprType con_expr') + (arg_tys, _) = tcSplitFunTys (exprType con_expr') + -- A newtype in the corner should be opaque; + -- hence TcType.tcSplitFunTys mk_arg (arg_ty, lbl) - = case [rhs | (sel_id,rhs,_) <- rbinds, + = case [rhs | (L _ sel_id, rhs) <- rbinds, lbl == recordSelectorFieldLabel sel_id] of (rhs:rhss) -> ASSERT( null rhss ) - dsExpr rhs - [] -> mkErrorAppDs rEC_CON_ERROR_ID arg_ty (showForErr lbl) + 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 in - mapDs mk_arg (zipEqual "dsExpr:RecordCon" arg_tys (dataConFieldLabels con_id)) `thenDs` \ con_args -> - mkAppDs con_expr' (map VarArg con_args) - where - -- "con_expr'" is simply an application of the constructor Id - -- to types and (perhaps) dictionaries. This gets the constructor... - get_con (Var con) = con - get_con (App fun _) = get_con fun + + (if null 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) \end{code} Record update is a little harder. Suppose we have the decl: - +\begin{verbatim} data T = T1 {op1, op2, op3 :: Int} | T2 {op4, op2 :: Int} | T3 - +\end{verbatim} Then we translate as follows: - +\begin{verbatim} r { op2 = e } ===> let op2 = e in @@ -390,268 +445,232 @@ Then we translate as follows: T1 op1 _ op3 -> T1 op1 op2 op3 T2 op4 _ -> T2 op4 op2 other -> recUpdError "M.lhs/230" - -It's important that we use the constructor Ids for T1, T2 etc on the -RHSs, and do not generate a Core Con directly, because the constructor +\end{verbatim} +It's important that we use the constructor Ids for @T1@, @T2@ etc on the +RHSs, and do not generate a Core constructor application directly, because the constructor might do some argument-evaluation first; and may have to throw away some dictionaries. \begin{code} -dsExpr (RecordUpdOut record_expr dicts rbinds) - = dsExpr record_expr `thenDs` \ record_expr' -> +dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty []) + = dsLExpr 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 - dsRbinds rbinds $ \ rbinds' -> + let - record_ty = coreExprType record_expr' - (tycon, inst_tys, cons) = --trace "DsExpr.getAppDataTyConExpandingDicts" $ - getAppDataTyConExpandingDicts record_ty - cons_to_upd = filter has_all_fields cons - - -- initial_args are passed to every constructor - initial_args = map TyArg inst_tys ++ map VarArg 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 + in_inst_tys = tcTyConAppArgs record_in_ty -- Newtype opaque + out_inst_tys = tcTyConAppArgs record_out_ty -- Newtype opaque + + mk_val_arg field old_arg_id + = case [rhs | (L _ sel_id, rhs) <- rbinds, + field == recordSelectorFieldLabel sel_id] of + (rhs:rest) -> ASSERT(null rest) rhs + [] -> nlHsVar old_arg_id mk_alt con - = newSysLocalsDs (dataConArgTys con inst_tys) `thenDs` \ arg_ids -> + = newSysLocalsDs (dataConInstOrigArgTys con in_inst_tys) `thenDs` \ arg_ids -> + -- This call to dataConArgTys won't work for existentials let - val_args = map mk_val_arg (zipEqual "dsExpr:RecordUpd" (dataConFieldLabels con) arg_ids) + val_args = zipWithEqual "dsExpr:RecordUpd" mk_val_arg + (dataConFieldLabels con) arg_ids + rhs = foldl (\a b -> nlHsApp a b) + (noLoc $ TyApp (nlHsVar (dataConWrapId con)) + out_inst_tys) + val_args in - returnDs (con, arg_ids, mkGenApp (mkGenApp (Var con) initial_args) val_args) - - mk_default - | length cons_to_upd == length cons - = returnDs NoDefault - | otherwise - = newSysLocalDs record_ty `thenDs` \ deflt_id -> - mkErrorAppDs rEC_UPD_ERROR_ID record_ty "" `thenDs` \ err -> - returnDs (BindDefault deflt_id err) + returnDs (mkSimpleMatch [noLoc $ ConPatOut con (PrefixCon (map nlVarPat arg_ids)) record_in_ty [] []] + rhs + record_out_ty) in - mapDs mk_alt cons_to_upd `thenDs` \ alts -> - mk_default `thenDs` \ deflt -> + -- 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 ) - returnDs (Case record_expr' (AlgAlts alts deflt)) + -- 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. + 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 - has_all_fields :: Id -> Bool + updated_fields :: [FieldLabel] + 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 + -- (In GHCI, it's possible that some TyCons may not have all + -- their constructors, in a module-loop situation.) + tycon = fieldLabelTyCon (head updated_fields) + data_cons = tyConDataCons tycon + cons_to_upd = filter has_all_fields data_cons + + has_all_fields :: DataCon -> Bool has_all_fields con_id - = all ok rbinds + = all (`elem` con_fields) updated_fields where - con_fields = dataConFieldLabels con_id - ok (sel_id, _, _) = recordSelectorFieldLabel sel_id `elem` con_fields + con_fields = dataConFieldLabels con_id \end{code} -Dictionary lambda and application -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +\noindent +\underline{\bf Dictionary lambda and application} +% ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @DictLam@ and @DictApp@ turn into the regular old things. (OLD:) @DictFunApp@ also becomes a curried application, albeit slightly more complicated; reminiscent of fully-applied constructors. \begin{code} dsExpr (DictLam dictvars expr) - = dsExpr expr `thenDs` \ core_expr -> - returnDs( mkValLam dictvars core_expr ) + = dsLExpr expr `thenDs` \ core_expr -> + returnDs (mkLams dictvars core_expr) ------------------ -dsExpr expr@(DictApp e dicts) -- becomes a curried application - = dsApp expr [] +dsExpr (DictApp expr dicts) -- becomes a curried application + = dsLExpr expr `thenDs` \ core_expr -> + returnDs (foldl (\f d -> f `App` (Var d)) core_expr dicts) \end{code} -@SingleDicts@ become @Locals@; @Dicts@ turn into tuples, unless -of length 0 or 1. -@ClassDictLam dictvars methods expr@ is ``the opposite'': -\begin{verbatim} -\ x -> case x of ( dictvars-and-methods-tuple ) -> expr -\end{verbatim} +Here is where we desugar the Template Haskell brackets and escapes + \begin{code} -dsExpr (SingleDict dict) -- just a local - = lookupEnvWithDefaultDs dict (Var dict) +-- Template Haskell stuff -dsExpr (Dictionary dicts methods) - = -- hey, these things may have been substituted away... - zipWithDs lookupEnvWithDefaultDs - dicts_and_methods dicts_and_methods_exprs - `thenDs` \ core_d_and_ms -> +#ifdef GHCI /* Only if bootstrapping */ +dsExpr (HsBracketOut x ps) = dsBracket x ps +dsExpr (HsSpliceE s) = pprPanic "dsExpr:splice" (ppr s) +#endif - (case num_of_d_and_ms of - 0 -> returnDs (Var voidId) +-- Arrow notation extension +dsExpr (HsProc pat cmd) = dsProcExpr pat cmd +\end{code} - 1 -> returnDs (head core_d_and_ms) -- just a single Id - _ -> -- tuple 'em up - mkConDs (tupleCon num_of_d_and_ms) - (map (TyArg . coreExprType) core_d_and_ms ++ map VarArg core_d_and_ms) - ) - where - dicts_and_methods = dicts ++ methods - dicts_and_methods_exprs = map Var dicts_and_methods - num_of_d_and_ms = length dicts_and_methods - -dsExpr (ClassDictLam dicts methods expr) - = dsExpr expr `thenDs` \ core_expr -> - case num_of_d_and_ms of - 0 -> newSysLocalDs voidTy `thenDs` \ new_x -> - returnDs (mkValLam [new_x] core_expr) - - 1 -> -- no untupling - returnDs (mkValLam dicts_and_methods core_expr) - - _ -> -- untuple it - newSysLocalDs tuple_ty `thenDs` \ new_x -> - returnDs ( - Lam (ValBinder new_x) - (Case (Var new_x) - (AlgAlts - [(tuple_con, dicts_and_methods, core_expr)] - NoDefault))) - where - num_of_d_and_ms = length dicts + length methods - dicts_and_methods = dicts ++ methods - tuple_ty = mkTupleTy num_of_d_and_ms (map idType dicts_and_methods) - tuple_con = tupleCon num_of_d_and_ms +\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 -out_of_range_msg -- ditto - = " out of range: [" ++ show minInt ++ ", " ++ show maxInt ++ "]\n" \end{code} %-------------------------------------------------------------------- -@(dsApp e [t_1,..,t_n, e_1,..,e_n])@ returns something with the same -value as: -\begin{verbatim} -e t_1 ... t_n e_1 .. e_n -\end{verbatim} - -We're doing all this so we can saturate constructors (as painlessly as -possible). +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} -dsApp :: TypecheckedHsExpr -- expr to desugar - -> [DsCoreArg] -- accumulated ty/val args: NB: - -> DsM CoreExpr -- final result - -dsApp (HsApp e1 e2) args - = dsExpr e2 `thenDs` \ core_e2 -> - dsApp e1 (VarArg core_e2 : args) - -dsApp (OpApp e1 op e2) args - = dsExpr e1 `thenDs` \ core_e1 -> - dsExpr e2 `thenDs` \ core_e2 -> - dsApp op (VarArg core_e1 : VarArg core_e2 : args) - -dsApp (DictApp expr dicts) args - = -- now, those dicts may have been substituted away... - zipWithDs lookupEnvWithDefaultDs dicts (map Var dicts) - `thenDs` \ core_dicts -> - dsApp expr (map VarArg core_dicts ++ args) - -dsApp (TyApp expr tys) args - = dsApp expr (map TyArg tys ++ args) - --- we might should look out for SectionLs, etc., here, but we don'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 -dsApp (HsVar v) args - = lookupEnvDs v `thenDs` \ maybe_expr -> - mkAppDs (case maybe_expr of { Nothing -> Var v; Just expr -> expr }) args +dsDo do_or_lc stmts ids result_ty + = dsReboundNames ids `thenDs` \ (meth_binds, ds_meths) -> + let + return_id = lookupReboundName ds_meths returnMName + fail_id = lookupReboundName ds_meths failMName + bind_id = lookupReboundName ds_meths bindMName + then_id = lookupReboundName ds_meths thenMName + + (m_ty, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b) + + -- 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] = dsLExpr expr + + + 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 stmts `thenDs` \ rest -> + dsLet binds rest + + 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 + in + 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_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 (map unLoc stmts) `thenDs` \ stmts_code -> + returnDs (foldr Let stmts_code meth_binds) -dsApp anything_else args - = dsExpr anything_else `thenDs` \ core_expr -> - mkAppDs core_expr args + where + mk_msg locn = "Pattern match failure in do expression at " ++ showSDoc (ppr locn) \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' -> - dsExprToAtom (VarArg rhs') $ \ rhs_atom -> - dsRbinds rbinds $ \ rbinds' -> - continue_with ((sel_id, rhs_atom) : rbinds') -\end{code} - -\begin{code} --- do_unfold ty_env val_env (Lam (TyBinder tyvar) body) (TyArg ty : args) --- = do_unfold (addOneToTyVarEnv ty_env tyvar ty) val_env body args --- --- do_unfold ty_env val_env (Lam (ValBinder binder) body) (arg@(VarArg expr) : args) --- = dsExprToAtom arg $ \ arg_atom -> --- do_unfold ty_env --- (addOneToIdEnv val_env binder (argToExpr arg_atom)) --- body args --- --- do_unfold ty_env val_env body args --- = -- Clone the remaining part of the template --- uniqSMtoDsM (substCoreExpr val_env ty_env body) `thenDs` \ body' -> --- --- -- Apply result to remaining arguments --- mkAppDs body' args -\end{code} +Translation for RecStmt's: +----------------------------- +We turn (RecStmt [v1,..vn] stmts) into: + + (v1,..,vn) <- mfix (\~(v1,..vn). do stmts + return (v1,..vn)) -Basically does the translation given in the Haskell~1.3 report: \begin{code} -dsDo :: Id -- id for: (>>=) m - -> Id -- id for: zero m - -> [TypecheckedStmt] - -> DsM CoreExpr - -dsDo then_id zero_id (stmt:stmts) - = case stmt of - ExprStmt expr locn -> ASSERT( null stmts ) do_expr expr locn - - ExprStmtOut expr locn a b -> - do_expr expr locn `thenDs` \ expr2 -> - ds_rest `thenDs` \ rest -> - newSysLocalDs a `thenDs` \ ignored_result_id -> - dsApp (HsVar then_id) [TyArg a, TyArg b, VarArg expr2, - VarArg (mkValLam [ignored_result_id] rest)] - - LetStmt binds -> - dsBinds False binds `thenDs` \ binds2 -> - ds_rest `thenDs` \ rest -> - returnDs (mkCoLetsAny binds2 rest) - - BindStmtOut pat expr locn a b -> - do_expr expr locn `thenDs` \ expr2 -> - let - zero_expr = TyApp (HsVar zero_id) [b] - main_match - = PatMatch pat (SimpleMatch (HsDoOut stmts then_id zero_id locn)) - the_matches - = if failureFreePat pat - then [main_match] - else [main_match, PatMatch (WildPat a) (SimpleMatch zero_expr)] - in - matchWrapper DoBindMatch the_matches "`do' statement" - `thenDs` \ (binders, matching_code) -> - dsApp (HsVar then_id) [TyArg a, TyArg b, - VarArg expr2, VarArg (mkValLam binders matching_code)] - where - ds_rest = dsDo then_id zero_id stmts - do_expr expr locn = putSrcLocDs locn (dsExpr expr) - -#ifdef DEBUG -dsDo then_expr zero_expr [] = panic "dsDo:[]" -#endif +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 vars == length rets ) + BindStmt tup_pat mfix_app + where + 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) + + 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}