%
-% (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(..), StmtCtxt(..), Match(..), HsBinds(..), MonoBinds(..),
)
import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds,
- TypecheckedRecordBinds, TypecheckedPat,
TypecheckedStmt,
maybeBoxedPrimType
import CoreSyn
import DsMonad
+import DsBinds ( dsMonoBinds )
+import DsGRHSs ( dsGuarded )
import DsCCall ( dsCCall )
import DsListComp ( dsListComp )
-import DsUtils ( mkAppDs, mkConDs, dsExprToAtomGivenTy,
- mkErrorAppDs, showForErr, DsCoreArg
- )
-import Match ( matchWrapper )
+import DsUtils ( mkErrorAppDs )
+import Match ( matchWrapper, matchSimply )
-import CoreUtils ( coreExprType, mkCoreIfThenElse )
+import CoreUtils ( coreExprType )
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 Id ( Id, idType, recordSelectorFieldLabel )
+import Const ( Con(..) )
+import DataCon ( DataCon, dataConId, dataConTyCon, dataConArgTys, dataConFieldLabels )
+import Const ( mkMachInt, Literal(..) )
+import PrelVals ( rEC_CON_ERROR_ID, rEC_UPD_ERROR_ID, iRREFUT_PAT_ERROR_ID )
import TyCon ( isNewTyCon )
-import Type ( splitFunTys, typePrimRep, mkTyConApp,
+import DataCon ( isExistentialDataCon )
+import Type ( splitFunTys, mkTyConApp,
splitAlgTyConApp, splitTyConApp_maybe,
- splitAppTy, Type
+ splitAppTy, isUnLiftedType, Type
)
-import TysWiredIn ( tupleCon, nilDataCon, consDataCon, listTyCon, mkListTy,
- charDataCon, charTy
+import TysWiredIn ( tupleCon, unboxedTupleCon,
+ consDataCon, listTyCon, mkListTy,
+ charDataCon, charTy, stringTy
)
-import TyVar ( GenTyVar{-instance Eq-} )
+import BasicTypes ( RecFlag(..) )
import Maybes ( maybeToBool )
-import Util ( zipEqual )
+import Util ( zipEqual, zipWithEqual )
import Outputable
-
-mk_nil_con ty = mkCon nilDataCon [ty] [] -- micro utility...
\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{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
+
+ C x# = e
+
+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
+dsLet (MonoBind (AbsBinds [] [] binder_triples bind) sigs is_rec) body
+ | or [isUnLiftedType (idType g) | (_, g, l) <- binder_triples]
+ = ASSERT (case is_rec of {NonRecursive -> True; other -> False})
+ putSrcLocDs loc $
+ dsGuarded grhss `thenDs` \ rhs ->
+ let
+ body' = foldr bind body binder_triples
+ bind (tyvars, g, l) body = ASSERT( null tyvars )
+ bindNonRec g (Var l) body
+ in
+ mkErrorAppDs iRREFUT_PAT_ERROR_ID result_ty (showSDoc (ppr pat)) `thenDs` \ error_expr ->
+ matchSimply rhs PatBindMatch pat body' error_expr
+ where
+ PatMonoBind pat grhss loc = bind
+ result_ty = coreExprType body
+
+-- Ordinary case for bindings
+dsLet (MonoBind binds sigs is_rec) body
+ = dsMonoBinds False binds [] `thenDs` \ prs ->
+ case is_rec of
+ Recursive -> returnDs (Let (Rec prs) body)
+ NonRecursive -> returnDs (foldr mk_let body prs)
+ where
+ mk_let (bndr,rhs) body = Let (NonRec bndr rhs) body
+\end{code}
%************************************************************************
%* *
\begin{code}
dsExpr :: TypecheckedHsExpr -> DsM CoreExpr
-dsExpr e@(HsVar var) = dsId var
+dsExpr e@(HsVar var) = returnDs (Var var)
\end{code}
%************************************************************************
\begin{code}
dsExpr (HsLitOut (HsString s) _)
| _NULL_ s
- = returnDs (mk_nil_con charTy)
+ = returnDs (mkNilExpr charTy)
| _LENGTH_ s == 1
= let
- the_char = mkCon charDataCon [] [LitArg (MachChar (_HEAD_ s))]
- the_nil = mk_nil_con charTy
+ the_char = mkConApp charDataCon [mkLit (MachChar (_HEAD_ s))]
+ the_nil = mkNilExpr charTy
+ the_cons = mkConApp consDataCon [Type charTy, the_char, the_nil]
in
- mkConDs consDataCon [TyArg charTy, VarArg the_char, VarArg the_nil]
+ returnDs the_cons
+
-- "_" => build (\ c n -> c 'c' n) -- LATER
-- the Core-to-STG pass will wrap it in an application of "unpackCStringId".
dsExpr (HsLitOut (HsString str) _)
- = returnDs (Lit (NoRepStr str))
+ = returnDs (mkLit (NoRepStr str stringTy))
-dsExpr (HsLitOut (HsLitLit s) ty)
- = returnDs ( mkCon data_con [] [LitArg (MachLitLit s kind)] )
+dsExpr (HsLitOut (HsLitLit str) ty)
+ = returnDs ( mkConApp data_con [mkLit (MachLitLit str prim_ty)] )
where
- (data_con, kind)
+ (data_con, prim_ty)
= case (maybeBoxedPrimType ty) of
- Just (boxing_data_con, prim_ty)
- -> (boxing_data_con, typePrimRep prim_ty)
+ Just (boxing_data_con, prim_ty) -> (boxing_data_con, prim_ty)
Nothing
-> pprPanic "ERROR: ``literal-literal'' not a single-constructor type: "
- (hcat [ptext s, text "; type: ", ppr ty])
+ (hcat [ptext str, text "; type: ", ppr ty])
dsExpr (HsLitOut (HsInt i) ty)
- = returnDs (Lit (NoRepInteger i ty))
+ = returnDs (mkLit (NoRepInteger i ty))
dsExpr (HsLitOut (HsFrac r) ty)
- = returnDs (Lit (NoRepRational r ty))
+ = returnDs (mkLit (NoRepRational r ty))
-- others where we know what to do:
dsExpr (HsLitOut (HsIntPrim i) _)
- | i >= toInteger minInt && i <= toInteger maxInt
- = returnDs (Lit (mkMachInt (fromInteger i)))
- | otherwise
+ | (i >= toInteger minInt && i <= toInteger maxInt)
+ = returnDs (mkLit (mkMachInt i))
+ | otherwise
= error ("ERROR: Int constant " ++ show i ++ out_of_range_msg)
dsExpr (HsLitOut (HsFloatPrim f) _)
- = returnDs (Lit (MachFloat f))
+ = returnDs (mkLit (MachFloat f))
-- ToDo: range checking needed!
dsExpr (HsLitOut (HsDoublePrim d) _)
- = returnDs (Lit (MachDouble d))
+ = returnDs (mkLit (MachDouble d))
-- ToDo: range checking needed!
dsExpr (HsLitOut (HsChar c) _)
- = returnDs ( mkCon charDataCon [] [LitArg (MachChar c)] )
+ = returnDs ( mkConApp charDataCon [mkLit (MachChar c)] )
dsExpr (HsLitOut (HsCharPrim c) _)
- = returnDs (Lit (MachChar c))
+ = returnDs (mkLit (MachChar c))
dsExpr (HsLitOut (HsStringPrim s) _)
- = returnDs (Lit (MachStr s))
+ = returnDs (mkLit (MachStr s))
-- end of literals magic. --
dsExpr expr@(HsLam a_Match)
= matchWrapper LambdaMatch [a_Match] "lambda" `thenDs` \ (binders, matching_code) ->
- returnDs ( mkValLam 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}
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 ->
(x_ty:y_ty:_, _) = splitFunTys (coreExprType core_op)
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)
let
(x_ty:y_ty:_, _) = splitFunTys (coreExprType core_op)
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)
= mapDs dsExpr args `thenDs` \ core_args ->
getModuleAndGroupDs `thenDs` \ (mod_name, group_name) ->
returnDs (Note (SCC (mkUserCC cc mod_name group_name)) core_expr)
-dsExpr expr@(HsCase discrim matches src_loc)
- = putSrcLocDs src_loc $
+-- special case to handle unboxed tuple patterns
+
+dsExpr (HsCase discrim matches@[PatMatch (TuplePat ps boxed) (GRHSMatch rhs)]
+ src_loc)
+ | all var_pat ps
+ = 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 )
+ 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))
-dsExpr (HsLet binds expr)
- = dsBinds False binds `thenDs` \ core_binds ->
- dsExpr expr `thenDs` \ core_expr ->
- returnDs ( mkCoLetsAny core_binds core_expr )
+dsExpr (HsCase discrim matches src_loc)
+ = putSrcLocDs src_loc $
+ dsExpr discrim `thenDs` \ core_discrim ->
+ matchWrapper CaseMatch matches "case" `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 (HsDoOut do_or_lc stmts return_id then_id zero_id result_ty src_loc)
| maybeToBool maybe_list_comp
= -- Special case for list comprehensions
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}
\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}
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])
+ returnDs (mkConApp consDataCon [Type ty, core_x, core_xs])
-dsExpr (ExplicitTuple expr_list)
+dsExpr (ExplicitTuple expr_list boxed)
= mapDs dsExpr expr_list `thenDs` \ core_exprs ->
- mkConDs (tupleCon (length expr_list))
- (map (TyArg . coreExprType) core_exprs ++ map VarArg core_exprs)
+ returnDs (mkConApp ((if boxed
+ then tupleCon
+ else unboxedTupleCon) (length expr_list))
+ (map (Type . coreExprType) core_exprs ++ core_exprs))
dsExpr (HsCon con_id [ty] [arg])
| isNewTyCon tycon
dsExpr (HsCon con_id tys args)
= mapDs dsExpr args `thenDs` \ args2 ->
- mkConDs con_id (map TyArg tys ++ map VarArg args2)
+ returnDs (mkConApp con_id (map Type tys ++ args2))
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])
\end{code}
Record construction and update
\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')
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))
in
- mapDs mk_arg (zipEqual "dsExpr:RecordCon" arg_tys (dataConFieldLabels con_id)) `thenDs` \ con_args ->
- mkAppDs con_expr' (map VarArg con_args)
+ mapDs mk_arg (zipEqual "dsExpr:RecordCon" arg_tys (dataConFieldLabels data_con)) `thenDs` \ con_args ->
+ returnDs (mkApps con_expr' con_args)
\end{code}
Record update is a little harder. Suppose we have the decl:
\begin{code}
dsExpr (RecordUpdOut record_expr record_out_ty dicts rbinds)
- = dsExpr record_expr `thenDs` \ record_expr' ->
+ = 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
+ ds_rbind (sel_id, rhs, pun_flag)
+ = dsExpr rhs `thenDs` \ rhs' ->
+ returnDs (recordSelectorFieldLabel sel_id, rhs')
+ in
+ mapDs ds_rbind rbinds `thenDs` \ rbinds' ->
let
record_in_ty = coreExprType record_expr'
(tycon, in_inst_tys, cons) = splitAlgTyConApp record_in_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
+ initial_args = map Type out_inst_tys ++ map Var 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
+ mk_val_arg field old_arg_id
+ = case [rhs | (f, rhs) <- rbinds', field == f] of
+ (rhs:rest) -> ASSERT(null rest) rhs
+ [] -> Var old_arg_id
mk_alt con
= newSysLocalsDs (dataConArgTys con in_inst_tys) `thenDs` \ arg_ids ->
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 = mkApps (mkApps (Var (dataConId con)) initial_args) val_args
in
- returnDs (con, arg_ids, mkGenApp (mkGenApp (Var con) initial_args) val_args)
+ returnDs (DataCon con, arg_ids, rhs)
mk_default
| length cons_to_upd == length cons
- = returnDs NoDefault
+ = returnDs []
| otherwise
- = newSysLocalDs record_in_ty `thenDs` \ deflt_id ->
- mkErrorAppDs rEC_UPD_ERROR_ID record_out_ty "" `thenDs` \ err ->
- returnDs (BindDefault deflt_id err)
+ = mkErrorAppDs rEC_UPD_ERROR_ID record_out_ty "" `thenDs` \ err ->
+ returnDs [(DEFAULT, [], err)]
in
+ -- Record stuff doesn't work for existentials
+ ASSERT( all (not . isExistentialDataCon) cons )
+
+ newSysLocalDs record_in_ty `thenDs` \ case_bndr ->
mapDs mk_alt cons_to_upd `thenDs` \ alts ->
mk_default `thenDs` \ deflt ->
- returnDs (Case record_expr' (AlgAlts alts deflt))
-
+ returnDs (Case record_expr' case_bndr (alts ++ deflt))
where
- has_all_fields :: Id -> Bool
+ has_all_fields :: DataCon -> Bool
has_all_fields con_id
= all ok rbinds
where
\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}
= " 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}
-
Basically does the translation given in the Haskell~1.3 report:
+
\begin{code}
-dsDo :: DoOrListComp
+dsDo :: StmtCtxt
-> [TypecheckedStmt]
-> Id -- id for: return m
-> Id -- id for: (>>=) m
-> 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
+ = let
(_, b_ty) = splitAppTy result_ty -- result_ty must be of the form (m b)
go [ReturnStmt expr]
= dsExpr expr `thenDs` \ expr2 ->
- mkAppDs return_ds [TyArg b_ty, VarArg expr2]
+ returnDs (mkApps (Var return_id) [Type b_ty, expr2])
go (GuardStmt expr locn : stmts)
= 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)
+ returnDs (mkIfThenElse expr2 rest (App (Var zero_id) (Type b_ty)))
go (ExprStmt expr locn : stmts)
= do_expr expr locn `thenDs` \ 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)]
+ returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2,
+ Lam ignored_result_id rest])
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 ->
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))
-
the_matches
- | failureFreePat pat = [main_match]
- | otherwise =
- [ main_match
- , PatMatch (WildPat a_ty) (SimpleMatch zero_expr)
- ]
+ = if failureFreePat pat
+ then [main_match]
+ else [main_match, PatMatch (WildPat a_ty) (SimpleMatch zero_expr)]
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)]
+ returnDs (mkApps (Var then_id) [Type a_ty, Type b_ty, expr2,
+ mkLams binders matching_code])
in
go stmts
DoStmt -> "`do' statement"
ListComp -> "comprehension"
\end{code}
+
+\begin{code}
+var_pat (WildPat _) = True
+var_pat (VarPat _) = True
+var_pat _ = False
+\end{code}
+
projects / ghc-hetmet.git / blobdiff