%
-% (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 ) where
+module DsExpr ( dsExpr, dsLet ) where
#include "HsVersions.h"
-import {-# SOURCE #-} DsBinds (dsBinds )
import HsSyn ( failureFreePat,
HsExpr(..), OutPat(..), HsLit(..), ArithSeqInfo(..),
- Stmt(..), DoOrListComp(..), Match(..), HsBinds, HsType, Fixity,
- GRHSsAndBinds
+ Stmt(..), HsMatchContext(..), HsDoContext(..),
+ Match(..), HsBinds(..), MonoBinds(..),
+ mkSimpleMatch
)
-import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds,
- TypecheckedRecordBinds, TypecheckedPat,
- TypecheckedStmt,
- maybeBoxedPrimType
+import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, outPatType )
- )
+-- NB: The desugarer, which straddles the source and Core worlds, sometimes
+-- needs to see source types (newtypes etc), and sometimes not
+-- So WATCH OUT; check each use of split*Ty functions.
+-- Sigh. This is a pain.
+
+import TcType ( tcSplitAppTy, tcSplitFunTys, tcSplitTyConApp_maybe, tcTyConAppArgs,
+ isIntegerTy, tcSplitTyConApp, isUnLiftedType, Type )
+import Type ( splitFunTys )
import CoreSyn
+import CoreUtils ( exprType, mkIfThenElse, bindNonRec )
import DsMonad
-import DsCCall ( dsCCall )
-import DsListComp ( dsListComp )
-import DsUtils ( mkAppDs, mkConDs, dsExprToAtomGivenTy,
- mkErrorAppDs, showForErr, DsCoreArg
+import DsBinds ( dsMonoBinds, AutoScc(..) )
+import DsGRHSs ( dsGuarded )
+import DsCCall ( dsCCall, resultWrapper )
+import DsListComp ( dsListComp, dsPArrComp )
+import DsUtils ( mkErrorAppDs, mkStringLit, mkStringLitFS,
+ mkConsExpr, mkNilExpr, mkIntegerLit
)
-import Match ( matchWrapper )
+import Match ( matchWrapper, matchSimply )
-import CoreUtils ( coreExprType, mkCoreIfThenElse )
+import FieldLabel ( FieldLabel, fieldLabelTyCon )
import CostCentre ( mkUserCC )
-import FieldLabel ( FieldLabel )
-import Id ( dataConTyCon, dataConArgTys, dataConFieldLabels,
- recordSelectorFieldLabel, Id
- )
-import Literal ( mkMachInt, Literal(..) )
-import Name ( Name{--O only-} )
-import PrelVals ( rEC_CON_ERROR_ID, rEC_UPD_ERROR_ID )
-import TyCon ( isNewTyCon )
-import Type ( splitFunTys, typePrimRep, mkTyConApp,
- splitAlgTyConApp, splitTyConApp_maybe,
- splitAppTy, Type
- )
-import TysWiredIn ( tupleCon, nilDataCon, consDataCon, listTyCon, mkListTy,
- charDataCon, charTy
- )
-import TyVar ( GenTyVar{-instance Eq-} )
+import Id ( Id, idType, recordSelectorFieldLabel )
+import PrelInfo ( rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID )
+import DataCon ( DataCon, dataConWrapId, dataConFieldLabels, dataConInstOrigArgTys )
+import DataCon ( isExistentialDataCon )
+import Literal ( Literal(..) )
+import TyCon ( tyConDataCons )
+import TysWiredIn ( tupleCon, listTyCon, charDataCon, intDataCon )
+import BasicTypes ( RecFlag(..), Boxity(..), ipNameName )
import Maybes ( maybeToBool )
-import Util ( zipEqual )
+import PrelNames ( hasKey, ratioTyConKey, toPName )
+import Util ( zipEqual, zipWithEqual )
import Outputable
-mk_nil_con ty = mkCon nilDataCon [ty] [] -- micro utility...
+import Ratio ( numerator, denominator )
\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}
%* *
%************************************************************************
-\begin{code}
-dsExpr :: TypecheckedHsExpr -> DsM CoreExpr
+@dsLet@ is a match-result transformer, taking the @MatchResult@ for the body
+and transforming it into one for the let-bindings enclosing the body.
-dsExpr e@(HsVar var) = dsId var
-\end{code}
+This may seem a bit odd, but (source) let bindings can contain unboxed
+binds like
+\begin{verbatim}
+ C x# = e
+\end{verbatim}
+This must be transformed to a case expression and, if the type has
+more than one constructor, may fail.
+
+\begin{code}
+dsLet :: TypecheckedHsBinds -> CoreExpr -> DsM CoreExpr
+
+dsLet EmptyBinds body
+ = returnDs body
+
+dsLet (ThenBinds b1 b2) body
+ = dsLet b2 body `thenDs` \ body' ->
+ dsLet b1 body'
+
+-- Special case for bindings which bind unlifted variables
+-- We need to do a case right away, rather than building
+-- a tuple and doing selections.
+-- Silently ignore INLINE pragmas...
+dsLet 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 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 [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
- -> pprPanic "ERROR: ``literal-literal'' not a single-constructor type: "
- (hcat [ptext s, text "; type: ", ppr ty])
-
-dsExpr (HsLitOut (HsInt i) ty)
- = returnDs (Lit (NoRepInteger i ty))
-
-dsExpr (HsLitOut (HsFrac r) ty)
- = returnDs (Lit (NoRepRational r ty))
-
--- 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 (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 fun arg)
= dsExpr fun `thenDs` \ core_fun ->
dsExpr arg `thenDs` \ core_arg ->
- dsExprToAtomGivenTy core_arg (coreExprType core_arg) $ \ atom_arg ->
- returnDs (core_fun `App` atom_arg)
-
+ returnDs (core_fun `App` core_arg)
\end{code}
Operator sections. At first it looks as if we can convert
dsExpr (OpApp e1 op _ e2)
= dsExpr op `thenDs` \ core_op ->
-- for the type of y, we need the type of op's 2nd argument
- let
- (x_ty:y_ty:_, _) = splitFunTys (coreExprType core_op)
- in
dsExpr e1 `thenDs` \ x_core ->
dsExpr e2 `thenDs` \ y_core ->
- dsExprToAtomGivenTy x_core x_ty $ \ x_atom ->
- dsExprToAtomGivenTy y_core y_ty $ \ y_atom ->
- returnDs (core_op `App` x_atom `App` y_atom)
+ returnDs (mkApps core_op [x_core, y_core])
dsExpr (SectionL expr op)
= dsExpr op `thenDs` \ core_op ->
-- for the type of y, we need the type of op's 2nd argument
let
- (x_ty:y_ty:_, _) = splitFunTys (coreExprType core_op)
+ (x_ty:y_ty:_, _) = splitFunTys (exprType core_op)
+ -- Must look through an implicit-parameter type;
+ -- newtype impossible; hence Type.splitFunTys
in
dsExpr expr `thenDs` \ x_core ->
- dsExprToAtomGivenTy x_core x_ty $ \ x_atom ->
-
+ newSysLocalDs x_ty `thenDs` \ x_id ->
newSysLocalDs y_ty `thenDs` \ y_id ->
- returnDs (mkValLam [y_id] (core_op `App` x_atom `App` VarArg 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 ->
-- for the type of x, we need the type of op's 2nd argument
let
- (x_ty:y_ty:_, _) = splitFunTys (coreExprType core_op)
+ (x_ty:y_ty:_, _) = splitFunTys (exprType core_op)
+ -- See comment with SectionL
in
- dsExpr expr `thenDs` \ y_expr ->
- dsExprToAtomGivenTy y_expr y_ty $ \ y_atom ->
-
+ dsExpr expr `thenDs` \ y_core ->
newSysLocalDs x_ty `thenDs` \ x_id ->
- returnDs (mkValLam [x_id] (core_op `App` VarArg x_id `App` y_atom))
+ 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)
+
+-- 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 expr@(HsCase discrim matches src_loc)
+dsExpr (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 (HsLet binds expr)
- = dsBinds False binds `thenDs` \ core_binds ->
- dsExpr expr `thenDs` \ core_expr ->
- returnDs ( mkCoLetsAny core_binds core_expr )
-
-dsExpr (HsDoOut do_or_lc stmts return_id then_id zero_id result_ty src_loc)
- | maybeToBool maybe_list_comp
+ 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'
+
+dsExpr (HsWith expr binds)
+ = dsExpr expr `thenDs` \ expr' ->
+ foldlDs dsIPBind expr' binds
+ where
+ dsIPBind body (n, e)
+ = dsExpr e `thenDs` \ e' ->
+ returnDs (Let (NonRec (ipNameName n) e') 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 (HsDoOut ListComp stmts return_id then_id fail_id result_ty src_loc)
= -- Special case for list comprehensions
putSrcLocDs src_loc $
dsListComp stmts elt_ty
+ where
+ (_, [elt_ty]) = tcSplitTyConApp result_ty
- | otherwise
+dsExpr (HsDoOut DoExpr stmts return_id then_id fail_id result_ty src_loc)
= putSrcLocDs src_loc $
- dsDo do_or_lc stmts return_id then_id zero_id result_ty
+ dsDo DoExpr stmts return_id then_id fail_id result_ty
+
+dsExpr (HsDoOut PArrComp stmts return_id then_id fail_id result_ty src_loc)
+ = -- Special case for array comprehensions
+ putSrcLocDs src_loc $
+ dsPArrComp stmts elt_ty
where
- maybe_list_comp
- = case (do_or_lc, splitTyConApp_maybe result_ty) of
- (ListComp, Just (tycon, [elt_ty]))
- | tycon == listTyCon
- -> Just elt_ty
- other -> Nothing
- -- We need the ListComp form to use deListComp (rather than the "do" form)
- -- because the "return" in a do block is a call to "PrelBase.return", and
- -- not a ReturnStmt. Only the ListComp form has ReturnStmts
-
- Just elt_ty = maybe_list_comp
+ (_, [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 (TyApp expr tys)
= dsExpr expr `thenDs` \ core_expr ->
- returnDs (mkTyApp core_expr tys)
+ returnDs (mkTyApps core_expr tys)
\end{code}
-Various data construction things
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+\noindent
+\underline{\bf Various data construction things}
+% ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-dsExpr (ExplicitListOut ty xs)
+dsExpr (ExplicitList ty xs)
= go xs
where
- list_ty = mkListTy ty
-
- -- xs can ocasaionlly be huge, so don't try to take
- -- coreExprType of core_xs, as dsArgToAtom does
- -- (that gives a quadratic algorithm)
- go [] = returnDs (mk_nil_con ty)
+ go [] = returnDs (mkNilExpr ty)
go (x:xs) = dsExpr x `thenDs` \ core_x ->
- dsExprToAtomGivenTy core_x ty $ \ arg_x ->
go xs `thenDs` \ core_xs ->
- dsExprToAtomGivenTy core_xs list_ty $ \ arg_xs ->
- returnDs (Con consDataCon [TyArg ty, arg_x, arg_xs])
-
-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)
+ returnDs (mkConsExpr ty core_x core_xs)
-dsExpr (HsCon con_id [ty] [arg])
- | isNewTyCon tycon
- = dsExpr arg `thenDs` \ arg' ->
- returnDs (Coerce (CoerceIn con_id) result_ty arg')
- where
- result_ty = mkTyConApp tycon [ty]
- tycon = dataConTyCon con_id
+-- 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)
+ = dsLookupGlobalValue toPName `thenDs` \toP ->
+ dsExpr (ExplicitList ty xs) `thenDs` \coreList ->
+ returnDs (mkApps (Var toP) [Type ty, coreList])
-dsExpr (HsCon con_id tys args)
- = mapDs dsExpr args `thenDs` \ args2 ->
- mkConDs con_id (map TyArg tys ++ map VarArg args2)
+dsExpr (ExplicitTuple expr_list boxity)
+ = mapDs dsExpr 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]
+ 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]
+ 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]
+ 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]
+ 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_id con_expr rbinds)
+dsExpr (RecordConOut data_con con_expr rbinds)
= dsExpr con_expr `thenDs` \ con_expr' ->
let
- (arg_tys, _) = splitFunTys (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,
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 (zipEqual "dsExpr:RecordCon" arg_tys (dataConFieldLabels con_id)) `thenDs` \ con_args ->
- mkAppDs con_expr' (map VarArg con_args)
+
+ (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 record_out_ty dicts rbinds)
- = dsExpr record_expr `thenDs` \ record_expr' ->
+dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty dicts [])
+ = dsExpr record_expr
+
+dsExpr (RecordUpdOut record_expr record_in_ty record_out_ty dicts 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_in_ty = coreExprType record_expr'
- (tycon, in_inst_tys, cons) = splitAlgTyConApp record_in_ty
- (_, out_inst_tys, _) = splitAlgTyConApp record_out_ty
- cons_to_upd = filter has_all_fields cons
-
- -- initial_args are passed to every constructor
- initial_args = map TyArg out_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 in_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 HsApp (DictApp (TyApp (HsVar (dataConWrapId con))
+ out_inst_tys)
+ dicts)
+ 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_in_ty `thenDs` \ deflt_id ->
- mkErrorAppDs rEC_UPD_ERROR_ID record_out_ty "" `thenDs` \ err ->
- returnDs (BindDefault deflt_id err)
+ returnDs (mkSimpleMatch [ConPat con record_in_ty [] [] (map VarPat arg_ids)]
+ 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
+ ASSERT( all (not . isExistentialDataCon) data_cons )
- 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.
+ mapDs 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 | (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 (DictApp expr dicts) -- becomes a curried application
- = mapDs lookupEnvDs dicts `thenDs` \ core_dicts ->
- dsExpr expr `thenDs` \ core_expr ->
- returnDs (foldl (\f d -> f `App` (VarArg d)) core_expr core_dicts)
+ = dsExpr expr `thenDs` \ core_expr ->
+ returnDs (foldl (\f d -> f `App` (Var d)) core_expr dicts)
\end{code}
\begin{code}
-
#ifdef DEBUG
-- HsSyn constructs that just shouldn't be here:
dsExpr (HsDo _ _ _) = panic "dsExpr:HsDo"
-dsExpr (ExplicitList _) = panic "dsExpr:ExplicitList"
dsExpr (ExprWithTySig _ _) = panic "dsExpr:ExprWithTySig"
dsExpr (ArithSeqIn _) = panic "dsExpr:ArithSeqIn"
+dsExpr (PArrSeqIn _) = panic "dsExpr:PArrSeqIn"
#endif
-out_of_range_msg -- ditto
- = " out of range: [" ++ show minInt ++ ", " ++ show maxInt ++ "]\n"
\end{code}
-
%--------------------------------------------------------------------
-\begin{code}
-dsId v
- = lookupEnvDs v `thenDs` \ v' ->
- returnDs (Var v')
-\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' ->
- dsExprToAtomGivenTy rhs' (coreExprType 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 (addToTyVarEnv 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}
-
Basically does the translation given in the Haskell~1.3 report:
+
\begin{code}
-dsDo :: DoOrListComp
+dsDo :: HsDoContext
-> [TypecheckedStmt]
-> Id -- id for: return m
-> Id -- id for: (>>=) m
- -> Id -- id for: zero m
+ -> Id -- id for: fail m
-> Type -- Element type; the whole expression has type (m t)
-> DsM CoreExpr
-dsDo do_or_lc stmts return_id then_id zero_id result_ty
- = dsId return_id `thenDs` \ return_ds ->
- dsId then_id `thenDs` \ then_ds ->
- dsId zero_id `thenDs` \ zero_ds ->
- let
- (_, b_ty) = splitAppTy result_ty -- result_ty must be of the form (m b)
+dsDo do_or_lc stmts return_id then_id fail_id result_ty
+ = let
+ (_, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b)
+ is_do = case do_or_lc of
+ DoExpr -> True
+ _ -> False
- go [ReturnStmt expr]
- = dsExpr expr `thenDs` \ expr2 ->
- mkAppDs return_ds [TyArg b_ty, VarArg expr2]
-
- go (GuardStmt expr locn : stmts)
+ -- For ExprStmt, see the comments near HsExpr.Stmt about
+ -- exactly what ExprStmts mean!
+ --
+ -- In dsDo we can only see DoStmt and ListComp (no gaurds)
+
+ go [ResultStmt expr locn]
+ | is_do = do_expr expr locn
+ | otherwise = do_expr expr locn `thenDs` \ expr2 ->
+ returnDs (mkApps (Var return_id) [Type b_ty, expr2])
+
+ go (ExprStmt expr a_ty locn : stmts)
+ | is_do -- Do expression
+ = do_expr expr locn `thenDs` \ expr2 ->
+ go stmts `thenDs` \ rest ->
+ newSysLocalDs a_ty `thenDs` \ ignored_result_id ->
+ returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2,
+ Lam ignored_result_id rest])
+
+ | otherwise -- List comprehension
= do_expr expr locn `thenDs` \ expr2 ->
go stmts `thenDs` \ rest ->
- mkAppDs zero_ds [TyArg b_ty] `thenDs` \ zero_expr ->
- returnDs (mkCoreIfThenElse expr2 rest zero_expr)
-
- go (ExprStmt expr locn : stmts)
- = do_expr expr locn `thenDs` \ expr2 ->
let
- (_, a_ty) = splitAppTy (coreExprType expr2) -- Must be of form (m a)
+ msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn)
in
- if null stmts then
- returnDs expr2
- else
- go stmts `thenDs` \ rest ->
- newSysLocalDs a_ty `thenDs` \ ignored_result_id ->
- mkAppDs then_ds [TyArg a_ty, TyArg b_ty, VarArg expr2,
- VarArg (mkValLam [ignored_result_id] rest)]
+ mkStringLit msg `thenDs` \ core_msg ->
+ returnDs (mkIfThenElse expr2 rest
+ (App (App (Var fail_id) (Type b_ty)) core_msg))
go (LetStmt binds : stmts )
- = dsBinds False binds `thenDs` \ binds2 ->
- go stmts `thenDs` \ rest ->
- returnDs (mkCoLetsAny binds2 rest)
-
+ = go stmts `thenDs` \ rest ->
+ dsLet binds rest
+
go (BindStmt pat expr locn : stmts)
= putSrcLocDs locn $
dsExpr expr `thenDs` \ expr2 ->
let
- (_, a_ty) = splitAppTy (coreExprType expr2) -- Must be of form (m a)
- zero_expr = TyApp (HsVar zero_id) [b_ty]
- main_match = PatMatch pat (SimpleMatch (
- HsDoOut do_or_lc stmts return_id then_id zero_id result_ty locn))
+ a_ty = outPatType pat
+ fail_expr = HsApp (TyApp (HsVar fail_id) [b_ty])
+ (HsLit (HsString (_PK_ msg)))
+ msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn)
+ main_match = mkSimpleMatch [pat]
+ (HsDoOut do_or_lc stmts return_id then_id
+ fail_id result_ty locn)
+ result_ty locn
the_matches
- = if failureFreePat pat
- then [main_match]
- else [main_match, PatMatch (WildPat a_ty) (SimpleMatch zero_expr)]
+ | failureFreePat pat = [main_match]
+ | otherwise =
+ [ main_match
+ , mkSimpleMatch [WildPat a_ty] fail_expr result_ty locn
+ ]
in
- matchWrapper DoBindMatch the_matches match_msg
- `thenDs` \ (binders, matching_code) ->
- mkAppDs then_ds [TyArg a_ty, TyArg b_ty,
- VarArg expr2, VarArg (mkValLam binders matching_code)]
+ matchWrapper (DoCtxt do_or_lc) the_matches `thenDs` \ (binders, matching_code) ->
+ returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2,
+ mkLams binders matching_code])
in
go stmts
where
do_expr expr locn = putSrcLocDs locn (dsExpr expr)
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection[DsExpr-literals]{Literals}
+%* *
+%************************************************************************
+
+We give int/float literals type @Integer@ and @Rational@, respectively.
+The typechecker will (presumably) have put \tr{from{Integer,Rational}s}
+around them.
+
+ToDo: put in range checks for when converting ``@i@''
+(or should that be in the typechecker?)
- match_msg = case do_or_lc of
- DoStmt -> "`do' statement"
- ListComp -> "comprehension"
+For numeric literals, we try to detect there use at a standard type
+(@Int@, @Float@, etc.) are directly put in the right constructor.
+[NB: down with the @App@ conversion.]
+
+See also below where we look for @DictApps@ for \tr{plusInt}, etc.
+
+\begin{code}
+dsLit :: HsLit -> DsM CoreExpr
+dsLit (HsChar c) = returnDs (mkConApp charDataCon [mkLit (MachChar c)])
+dsLit (HsCharPrim c) = returnDs (mkLit (MachChar c))
+dsLit (HsString str) = mkStringLitFS str
+dsLit (HsStringPrim s) = returnDs (mkLit (MachStr s))
+dsLit (HsInteger i) = mkIntegerLit i
+dsLit (HsInt i) = returnDs (mkConApp intDataCon [mkIntLit i])
+dsLit (HsIntPrim i) = returnDs (mkIntLit i)
+dsLit (HsFloatPrim f) = returnDs (mkLit (MachFloat f))
+dsLit (HsDoublePrim d) = returnDs (mkLit (MachDouble d))
+dsLit (HsLitLit str ty)
+ = ASSERT( maybeToBool maybe_ty )
+ returnDs (wrap_fn (mkLit (MachLitLit str rep_ty)))
+ where
+ (maybe_ty, wrap_fn) = resultWrapper ty
+ Just rep_ty = maybe_ty
+
+dsLit (HsRat r ty)
+ = mkIntegerLit (numerator r) `thenDs` \ num ->
+ mkIntegerLit (denominator r) `thenDs` \ denom ->
+ returnDs (mkConApp ratio_data_con [Type integer_ty, num, denom])
+ where
+ (ratio_data_con, integer_ty)
+ = case tcSplitTyConApp ty of
+ (tycon, [i_ty]) -> ASSERT(isIntegerTy i_ty && tycon `hasKey` ratioTyConKey)
+ (head (tyConDataCons tycon), i_ty)
\end{code}
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