X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsExpr.lhs;h=6ef07ffee914e1665b2611f268c6101a53414c06;hb=05afb7485eea44d6410139f8a20c94b6f66c46f2;hp=a9c4ffcfdd9d804a3951831f7b9883103b04281b;hpb=cc051dd76d01b61caae6f4e1fc177c9815716961;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsExpr.lhs b/ghc/compiler/deSugar/DsExpr.lhs index a9c4ffc..6ef07ff 100644 --- a/ghc/compiler/deSugar/DsExpr.lhs +++ b/ghc/compiler/deSugar/DsExpr.lhs @@ -1,189 +1,180 @@ % -% (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, dsLet, dsLit ) where + #include "HsVersions.h" -module DsExpr ( dsExpr ) where -import Ubiq -import DsLoop -- partly to get dsBinds, partly to chk dsExpr +import Match ( matchWrapper, matchSimply ) +import MatchLit ( dsLit ) +import DsBinds ( dsMonoBinds, AutoScc(..) ) +import DsGRHSs ( dsGuarded ) +import DsCCall ( dsCCall ) +import DsListComp ( dsListComp, dsPArrComp ) +import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr, + mkCoreTupTy, selectMatchVar, + dsReboundNames, lookupReboundName ) +import DsArrows ( dsProcExpr ) +import DsMonad -import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), - Match, Qual, HsBinds, Stmt, PolyType ) -import TcHsSyn ( TypecheckedHsExpr(..), TypecheckedHsBinds(..), - TypecheckedRecordBinds(..) - ) -import CoreSyn +#ifdef GHCI + -- Template Haskell stuff iff bootstrapped +import DsMeta ( dsBracket, dsReify ) +#endif -import DsMonad -import DsCCall ( dsCCall ) -import DsListComp ( dsListComp ) -import DsUtils ( mkAppDs, mkConDs, mkPrimDs, dsExprToAtom, - mkErrorAppDs, showForErr +import HsSyn ( HsExpr(..), Pat(..), ArithSeqInfo(..), + Stmt(..), HsMatchContext(..), HsStmtContext(..), + Match(..), HsBinds(..), MonoBinds(..), HsConDetails(..), + ReboundNames, + mkSimpleMatch, isDoExpr ) -import Match ( matchWrapper ) +import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, hsPatType ) -import CoreUnfold ( UnfoldingDetails(..), UnfoldingGuidance(..), - FormSummary ) -import CoreUtils ( coreExprType, substCoreExpr, argToExpr, - mkCoreIfThenElse, unTagBinders ) -import CostCentre ( mkUserCC ) -import FieldLabel ( fieldLabelType, FieldLabel ) -import Id ( mkTupleCon, idType, nullIdEnv, addOneToIdEnv, - getIdUnfolding, dataConArgTys, dataConFieldLabels, - recordSelectorFieldLabel - ) -import Literal ( mkMachInt, Literal(..) ) -import MagicUFs ( MagicUnfoldingFun ) -import PprStyle ( PprStyle(..) ) -import PprType ( GenType ) -import PrelInfo ( mkTupleTy, unitTy, nilDataCon, consDataCon, - charDataCon, charTy, rEC_CON_ERROR_ID, - rEC_UPD_ERROR_ID - ) -import Pretty ( ppShow, ppBesides, ppPStr, ppStr ) -import Type ( splitSigmaTy, splitFunTy, typePrimRep, getAppDataTyCon ) -import TyVar ( GenTyVar, nullTyVarEnv, addOneToTyVarEnv ) -import Usage ( UVar(..) ) -import Util ( zipEqual, pprError, panic, assertPanic ) +-- 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. -maybeBoxedPrimType = panic "DsExpr.maybeBoxedPrimType" -splitTyArgs = panic "DsExpr.splitTyArgs" +import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppArgs, + tcSplitTyConApp, isUnLiftedType, Type, + mkAppTy ) +import Type ( splitFunTys ) +import CoreSyn +import CoreUtils ( exprType, mkIfThenElse, bindNonRec ) -mk_nil_con ty = mkCon nilDataCon [] [ty] [] -- micro utility... +import FieldLabel ( FieldLabel, fieldLabelTyCon ) +import CostCentre ( mkUserCC ) +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 ( noSrcLoc ) +import Util ( zipEqual, zipWithEqual ) +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 :: TypecheckedHsBinds -> CoreExpr -> DsM CoreExpr -dsExpr (HsVar var) = dsApp (HsVar var) [] -\end{code} +dsLet EmptyBinds body + = returnDs body + +dsLet (ThenBinds b1 b2) body + = dsLet b2 body `thenDs` \ body' -> + dsLet b1 body' + +dsLet (IPBinds binds is_with) body + = foldlDs dsIPBind body binds + where + dsIPBind body (n, e) + = dsExpr 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... +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 + -- + -- 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 (idName fun)) matches `thenDs` \ (args, rhs) -> + ASSERT( null args ) -- Functions aren't lifted + returnDs (bindNonRec fun rhs body_w_exports) + + PatMonoBind pat grhss loc + -> putSrcLocDs loc $ + dsGuarded grhss `thenDs` \ rhs -> + mk_error_app pat `thenDs` \ error_expr -> + matchSimply rhs PatBindRhs pat body_w_exports error_expr + + other -> pprPanic "dsLet: unlifted" (ppr bind $$ ppr body) + where + body_w_exports = foldr bind_export body exports + bind_export (tvs, g, l) body = ASSERT( null tvs ) + bindNonRec g (Var l) body + + mk_error_app pat = mkErrorAppDs iRREFUT_PAT_ERROR_ID + (exprType body) + (showSDoc (ppr pat)) + +-- Ordinary case for bindings +dsLet (MonoBind binds sigs is_rec) body + = dsMonoBinds NoSccs binds [] `thenDs` \ prs -> + returnDs (Let (Rec prs) body) + -- Use a Rec regardless of is_rec. + -- Why? Because it allows the MonoBinds 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 [charTy] [the_char, 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) _) - = returnDs (Lit (NoRepInteger i)) - -dsExpr (HsLitOut (HsFrac r) _) - = returnDs (Lit (NoRepRational r)) - --- others where we know what to do: - -dsExpr (HsLitOut (HsIntPrim i) _) - = if (i >= toInteger minInt && i <= toInteger maxInt) then - returnDs (Lit (mkMachInt i)) - else - error ("ERROR: Int constant " ++ show i ++ out_of_range_msg) - -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)) +dsExpr :: TypecheckedHsExpr -> DsM CoreExpr --- end of literals magic. -- +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 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) + = dsExpr fun `thenDs` \ core_fun -> + dsExpr arg `thenDs` \ core_arg -> + returnDs (core_fun `App` core_arg) \end{code} Operator sections. At first it looks as if we can convert @@ -208,183 +199,261 @@ If \tr{expr} is actually just a variable, say, then the simplifier will sort it out. \begin{code} +dsExpr (OpApp e1 op _ e2) + = dsExpr 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 -> + returnDs (mkApps core_op [x_core, y_core]) + dsExpr (SectionL expr op) - = dsExpr op `thenDs` \ core_op -> - dsExpr expr `thenDs` \ core_expr -> - dsExprToAtom core_expr $ \ y_atom -> - - -- for the type of x, we need the type of op's 2nd argument + = dsExpr 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 (splitTyArgs 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)) + dsExpr 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 dsExpr (SectionR op expr) = dsExpr op `thenDs` \ core_op -> - dsExpr expr `thenDs` \ core_expr -> - dsExprToAtom core_expr $ \ y_atom -> - - -- for the type of x, we need the type of op's 1st argument + -- 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 (splitTyArgs 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)) + dsExpr 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 (CCall label args may_gc is_asm result_ty) +dsExpr (HsCCall lbl args may_gc is_asm result_ty) = mapDs dsExpr args `thenDs` \ core_args -> - dsCCall label core_args may_gc is_asm result_ty + 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 -> - getModuleAndGroupDs `thenDs` \ (mod_name, group_name) -> - returnDs ( SCC (mkUserCC cc mod_name group_name) core_expr) + getModuleDs `thenDs` \ mod_name -> + returnDs (Note (SCC (mkUserCC cc mod_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 +-- hdaume: core annotation + +dsExpr (HsCoreAnn fs expr) + = dsExpr expr `thenDs` \ core_expr -> + returnDs (Note (CoreNote $ unpackFS fs) core_expr) -dsExpr (HsLet binds expr) - = dsBinds binds `thenDs` \ core_binds -> - dsExpr expr `thenDs` \ core_expr -> - returnDs ( mkCoLetsAny core_binds 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 -> + 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 -dsExpr (HsDoOut stmts m_id mz_id src_loc) +dsExpr (HsCase discrim matches src_loc) = putSrcLocDs src_loc $ - panic "dsExpr:HsDoOut" + dsExpr 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' + +-- 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) + = -- Special case for list comprehensions + putSrcLocDs src_loc $ + dsListComp stmts elt_ty + where + (_, [elt_ty]) = tcSplitTyConApp result_ty + +dsExpr (HsDo do_or_lc stmts ids result_ty src_loc) + | isDoExpr do_or_lc + = putSrcLocDs src_loc $ + dsDo do_or_lc stmts ids result_ty + +dsExpr (HsDo PArrComp stmts _ result_ty src_loc) + = -- Special case for array comprehensions + putSrcLocDs src_loc $ + dsPArrComp stmts elt_ty + where + (_, [elt_ty]) = tcSplitTyConApp result_ty dsExpr (HsIf guard_expr then_expr else_expr src_loc) = putSrcLocDs src_loc $ dsExpr guard_expr `thenDs` \ core_guard -> dsExpr then_expr `thenDs` \ core_then -> dsExpr else_expr `thenDs` \ core_else -> - returnDs (mkCoreIfThenElse core_guard core_then 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) + returnDs (mkLams tyvars core_expr) -dsExpr expr@(TyApp e tys) = dsApp expr [] +dsExpr (TyApp expr tys) + = dsExpr 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 [ty] [core_hd, core_tl] - -dsExpr (ExplicitTuple expr_list) +dsExpr (ExplicitList ty xs) + = go xs + where + go [] = returnDs (mkNilExpr ty) + go (x:xs) = dsExpr 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 -> - mkConDs (mkTupleCon (length expr_list)) - (map coreExprType core_exprs) - core_exprs - -dsExpr (HsCon con tys args) - = mapDs dsExpr args `thenDs` \ args_exprs -> - mkConDs con tys args_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 [] [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 [] [from2, 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 [] [from2, 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 [] [from2, thn2, two2] + returnDs (mkApps expr2 [from2, thn2, two2]) + +dsExpr (PArrSeqOut expr (FromTo from two)) + = dsExpr expr `thenDs` \ expr2 -> + dsExpr from `thenDs` \ from2 -> + dsExpr two `thenDs` \ two2 -> + returnDs (mkApps expr2 [from2, two2]) + +dsExpr (PArrSeqOut expr (FromThenTo from thn two)) + = dsExpr expr `thenDs` \ expr2 -> + dsExpr from `thenDs` \ from2 -> + dsExpr thn `thenDs` \ thn2 -> + dsExpr two `thenDs` \ two2 -> + 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 (RecordConOut data_con con_expr rbinds) = dsExpr 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 | (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) + [] -> 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 (arg_tys `zipEqual` dataConFieldLabels con_id) `thenDs` \ con_args -> - mkAppDs con_expr' [] 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 mapDs unlabelled_bottom arg_tys + else mapDs 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 @@ -392,248 +461,247 @@ 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 []) + = dsExpr record_expr + +dsExpr expr@(RecordUpdOut record_expr record_in_ty record_out_ty rbinds) + = getSrcLocDs `thenDs` \ src_loc -> + dsExpr record_expr `thenDs` \ record_expr' -> -- Desugar the rbinds, and generate let-bindings if -- necessary so that we don't lose sharing - dsRbinds rbinds $ \ rbinds' -> + let - record_ty = coreExprType record_expr' - (tycon, inst_tys, cons) = _trace "getAppDataTyCon.DsExpr" $ getAppDataTyCon 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 | (sel_id, rhs) <- rbinds, + field == recordSelectorFieldLabel sel_id] of + (rhs:rest) -> ASSERT(null rest) rhs + [] -> HsVar 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 (dataConFieldLabels con `zipEqual` arg_ids) + val_args = zipWithEqual "dsExpr:RecordUpd" mk_val_arg + (dataConFieldLabels con) arg_ids + rhs = foldl HsApp (TyApp (HsVar (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 [ConPatOut con (PrefixCon (map VarPat arg_ids)) record_in_ty [] []] + rhs + record_out_ty + src_loc) 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 ) + + -- 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) -> - returnDs (Case record_expr' (AlgAlts alts deflt)) + returnDs (bindNonRec discrim_var record_expr' matching_code) where - has_all_fields :: Id -> Bool + updated_fields :: [FieldLabel] + updated_fields = [recordSelectorFieldLabel sel_id | (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 ) + returnDs (mkLams dictvars core_expr) ------------------ -dsExpr expr@(DictApp e dicts) -- becomes a curried application - = dsApp expr [] +dsExpr (DictApp expr dicts) -- becomes a curried application + = dsExpr 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} -\begin{code} -dsExpr (SingleDict dict) -- just a local - = lookupEnvWithDefaultDs dict (Var dict) +Here is where we desugar the Template Haskell brackets and escapes -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 -> +\begin{code} +-- Template Haskell stuff - (case num_of_d_and_ms of - 0 -> returnDs cocon_unit -- unit +#ifdef GHCI /* Only if bootstrapping */ +dsExpr (HsBracketOut x ps) = dsBracket x ps +dsExpr (HsReify r) = dsReify r +dsExpr (HsSplice n e _) = pprPanic "dsExpr:splice" (ppr e) +#endif - 1 -> returnDs (head core_d_and_ms) -- just a single Id +-- Arrow notation extension +dsExpr (HsProc pat cmd src_loc) = dsProcExpr pat cmd src_loc +\end{code} - _ -> -- tuple 'em up - mkConDs (mkTupleCon num_of_d_and_ms) - (map coreExprType core_d_and_ms) - 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 unitTy `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 = mkTupleCon 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 -cocon_unit = mkCon (mkTupleCon 0) [] [] [] -- out here to avoid CAF (sigh) -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). +Basically does the translation given in the Haskell~1.3 report: \begin{code} -type DsCoreArg = GenCoreArg CoreExpr{-NB!-} TyVar UVar - -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 - -dsApp (HsVar v) args - = lookupEnvDs v `thenDs` \ maybe_expr -> - case maybe_expr of - Just expr -> apply_to_args expr args - - Nothing -> -- we're only saturating constructors and PrimOps - case getIdUnfolding v of - GenForm _ _ the_unfolding EssentialUnfolding - -> do_unfold nullTyVarEnv nullIdEnv (unTagBinders the_unfolding) args - - _ -> apply_to_args (Var v) args - - -dsApp anything_else args - = dsExpr anything_else `thenDs` \ core_expr -> - apply_to_args core_expr args - --- a DsM version of mkGenApp: -apply_to_args :: CoreExpr -> [DsCoreArg] -> DsM CoreExpr - -apply_to_args fun args - = let - (ty_args, val_args) = foldr sep ([],[]) args +dsDo :: HsStmtContext Name + -> [TypecheckedStmt] + -> ReboundNames Id -- id for: [return,fail,>>=,>>] and possibly mfixName + -> Type -- Element type; the whole expression has type (m t) + -> DsM CoreExpr + +dsDo do_or_lc stmts ids result_ty + = dsReboundNames ids `thenDs` \ (meth_binds, ds_meths) -> + let + return_id = lookupReboundName ds_meths returnMName + fail_id = lookupReboundName ds_meths failMName + bind_id = lookupReboundName ds_meths bindMName + then_id = lookupReboundName ds_meths thenMName + + (m_ty, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b) + is_do = isDoExpr do_or_lc -- True for both MDo and Do + + -- For ExprStmt, see the comments near HsExpr.Stmt about + -- exactly what ExprStmts mean! + -- + -- In dsDo we can only see DoStmt and ListComp (no guards) + + go [ResultStmt expr locn] + | is_do = do_expr expr locn + | otherwise = do_expr expr locn `thenDs` \ expr2 -> + returnDs (mkApps 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 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 fail_id (Type b_ty)) core_msg)) + + go (LetStmt binds : stmts) + = go stmts `thenDs` \ rest -> + dsLet binds rest + + go (BindStmt pat expr locn : stmts) + = go stmts `thenDs` \ body -> + putSrcLocDs locn $ -- Rest is associated with this location + dsExpr expr `thenDs` \ rhs -> + mkStringLit (mk_msg locn) `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 + selectMatchVar 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 - mkAppDs fun ty_args val_args + go stmts `thenDs` \ stmts_code -> + returnDs (foldr Let stmts_code meth_binds) + where - sep a@(LitArg l) (tys,vals) = (tys, (Lit l):vals) - sep a@(VarArg e) (tys,vals) = (tys, e:vals) - sep a@(TyArg ty) (tys,vals) = (ty:tys, vals) - sep a@(UsageArg _) _ = panic "DsExpr:apply_to_args:UsageArg" + do_expr expr locn = putSrcLocDs locn (dsExpr expr) + mk_msg locn = "Pattern match failure in do expression at " ++ showSDoc (ppr locn) \end{code} +Translation for RecStmt's: +----------------------------- +We turn (RecStmt [v1,..vn] stmts) into: + + (v1,..,vn) <- mfix (\~(v1,..vn). do stmts + return (v1,..vn)) \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 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) (VarArg expr : args) - = dsExprToAtom expr $ \ 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 - apply_to_args body' args +dsRecStmt :: Type -- Monad type constructor :: * -> * + -> [(Name,Id)] -- Rebound Ids + -> [TypecheckedStmt] + -> [Id] -> [Id] -> [TypecheckedHsExpr] + -> TypecheckedStmt +dsRecStmt m_ty ds_meths stmts later_vars rec_vars rec_rets + = ASSERT( length vars == length rets ) + BindStmt tup_pat mfix_app noSrcLoc + where + vars@(var1:rest) = later_vars ++ rec_vars -- Always at least one + rets@(ret1:_) = map HsVar later_vars ++ rec_rets + one_var = null rest + + mfix_app = HsApp (TyApp (HsVar mfix_id) [tup_ty]) mfix_arg + mfix_arg = HsLam (mkSimpleMatch [tup_pat] body tup_ty noSrcLoc) + + tup_expr | one_var = ret1 + | otherwise = ExplicitTuple rets Boxed + tup_ty = mkCoreTupTy (map idType vars) + -- Deals with singleton case + tup_pat | one_var = VarPat var1 + | otherwise = LazyPat (TuplePat (map VarPat vars) Boxed) + + body = HsDo DoExpr (stmts ++ [return_stmt]) + [(n, HsVar id) | (n,id) <- ds_meths] -- A bit of a hack + (mkAppTy m_ty tup_ty) + noSrcLoc + + Var return_id = lookupReboundName ds_meths returnMName + Var mfix_id = lookupReboundName ds_meths mfixName + + return_stmt = ResultStmt return_app noSrcLoc + return_app = HsApp (TyApp (HsVar return_id) [tup_ty]) tup_expr \end{code}