%
-% (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
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
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}
projects / ghc-hetmet.git / blobdiff