\section[DsExpr]{Matching expressions (Exprs)}
\begin{code}
-module DsExpr ( dsExpr, dsLet ) where
+module DsExpr ( dsExpr, dsLet, dsLit ) where
#include "HsVersions.h"
-import HsSyn ( failureFreePat,
- HsExpr(..), OutPat(..), HsLit(..), ArithSeqInfo(..),
- Stmt(..), HsMatchContext(..), HsDoContext(..),
- Match(..), HsBinds(..), MonoBinds(..),
- mkSimpleMatch
+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
+
+#ifdef GHCI
+ -- Template Haskell stuff iff bootstrapped
+import DsMeta ( dsBracket, dsReify )
+#endif
+
+import HsSyn ( HsExpr(..), Pat(..), ArithSeqInfo(..),
+ Stmt(..), HsMatchContext(..), HsStmtContext(..),
+ Match(..), HsBinds(..), MonoBinds(..), HsConDetails(..),
+ ReboundNames,
+ mkSimpleMatch, isDoExpr
)
-import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, outPatType )
+import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, hsPatType )
-- NB: The desugarer, which straddles the source and Core worlds, sometimes
-- needs to see source types (newtypes etc), and sometimes not
-- Sigh. This is a pain.
import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppArgs,
- isIntegerTy, tcSplitTyConApp, isUnLiftedType, Type )
+ tcSplitTyConApp, isUnLiftedType, Type,
+ mkAppTy )
import Type ( splitFunTys )
import CoreSyn
import CoreUtils ( exprType, mkIfThenElse, bindNonRec )
-import DsMonad
-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, matchSimply )
-
import FieldLabel ( FieldLabel, fieldLabelTyCon )
import CostCentre ( mkUserCC )
-import Id ( Id, idType, recordSelectorFieldLabel )
+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 Literal ( Literal(..) )
+import Name ( Name )
import TyCon ( tyConDataCons )
-import TysWiredIn ( tupleCon, charDataCon, intDataCon )
+import TysWiredIn ( tupleCon, mkTupleTy )
import BasicTypes ( RecFlag(..), Boxity(..), ipNameName )
-import Maybes ( maybeToBool )
-import PrelNames ( hasKey, ratioTyConKey, toPName )
+import PrelNames ( toPName,
+ returnMName, bindMName, thenMName, failMName,
+ mfixName )
+import SrcLoc ( noSrcLoc )
import Util ( zipEqual, zipWithEqual )
import Outputable
import FastString
-
-import Ratio ( numerator, denominator )
\end{code}
= 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.
-- below. Then pattern-match would fail. Urk.)
case binds of
FunMonoBind fun _ matches loc
- -> putSrcLocDs loc $
- matchWrapper (FunRhs fun) matches `thenDs` \ (args, rhs) ->
+ -> putSrcLocDs loc $
+ matchWrapper (FunRhs (idName fun)) matches `thenDs` \ (args, rhs) ->
ASSERT( null args ) -- Functions aren't lifted
returnDs (bindNonRec fun rhs body_w_exports)
\begin{code}
dsExpr :: TypecheckedHsExpr -> DsM CoreExpr
+dsExpr (HsPar x) = dsExpr x
dsExpr (HsVar var) = returnDs (Var var)
dsExpr (HsIPVar ip) = returnDs (Var (ipNameName ip))
dsExpr (HsLit lit) = dsLit lit
getModuleDs `thenDs` \ mod_name ->
returnDs (Note (SCC (mkUserCC cc mod_name)) core_expr)
+
+-- hdaume: core annotation
+
+dsExpr (HsCoreAnn fs expr)
+ = dsExpr expr `thenDs` \ core_expr ->
+ returnDs (Note (CoreNote $ unpackFS fs) core_expr)
+
-- special case to handle unboxed tuple patterns.
dsExpr (HsCase discrim matches src_loc)
= dsExpr body `thenDs` \ body' ->
dsLet binds body'
-dsExpr (HsWith expr binds is_with)
- = 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.
--
where
(_, [elt_ty]) = tcSplitTyConApp result_ty
-dsExpr (HsDo DoExpr stmts ids result_ty src_loc)
+dsExpr (HsDo do_or_lc stmts ids result_ty src_loc)
+ | isDoExpr do_or_lc
= putSrcLocDs src_loc $
- dsDo DoExpr stmts ids result_ty
+ dsDo do_or_lc stmts ids result_ty
dsExpr (HsDo PArrComp stmts _ result_ty src_loc)
= -- Special case for array comprehensions
-- here at compile time
--
dsExpr (ExplicitPArr ty xs)
- = dsLookupGlobalValue toPName `thenDs` \toP ->
+ = dsLookupGlobalId toPName `thenDs` \toP ->
dsExpr (ExplicitList ty xs) `thenDs` \coreList ->
returnDs (mkApps (Var toP) [Type ty, coreList])
-- 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
out_inst_tys = tcTyConAppArgs record_out_ty -- Newtype opaque
mk_val_arg field old_arg_id
- = case [rhs | (sel_id, rhs, _) <- rbinds,
+ = case [rhs | (sel_id, rhs) <- rbinds,
field == recordSelectorFieldLabel sel_id] of
(rhs:rest) -> ASSERT(null rest) rhs
[] -> HsVar old_arg_id
rhs = foldl HsApp (TyApp (HsVar (dataConWrapId con)) out_inst_tys)
val_args
in
- returnDs (mkSimpleMatch [ConPat con record_in_ty [] [] (map VarPat arg_ids)]
+ returnDs (mkSimpleMatch [ConPatOut con (PrefixCon (map VarPat arg_ids)) record_in_ty [] []]
rhs
record_out_ty
src_loc)
where
updated_fields :: [FieldLabel]
- updated_fields = [recordSelectorFieldLabel sel_id | (sel_id,_,_) <- rbinds]
+ 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
returnDs (foldl (\f d -> f `App` (Var d)) core_expr dicts)
\end{code}
+Here is where we desugar the Template Haskell brackets and escapes
+
+\begin{code}
+-- Template Haskell stuff
+
+#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
+
+-- Arrow notation extension
+dsExpr (HsProc pat cmd src_loc) = dsProcExpr pat cmd src_loc
+\end{code}
+
+
\begin{code}
#ifdef DEBUG
Basically does the translation given in the Haskell~1.3 report:
\begin{code}
-dsDo :: HsDoContext
+dsDo :: HsStmtContext Name
-> [TypecheckedStmt]
- -> [Id] -- id for: [return,fail,>>=,>>]
- -> Type -- Element type; the whole expression has type (m t)
+ -> 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@[return_id, fail_id, bind_id, then_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
+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!
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])
+ 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 (Var then_id) [Type a_ty, Type b_ty, expr2, rest])
+ returnDs (mkApps then_id [Type a_ty, Type b_ty, expr2, rest])
| otherwise -- List comprehension
= do_expr expr locn `thenDs` \ expr2 ->
in
mkStringLit msg `thenDs` \ core_msg ->
returnDs (mkIfThenElse expr2 rest
- (App (App (Var fail_id) (Type b_ty)) core_msg))
+ (App (App fail_id (Type b_ty)) core_msg))
- go (LetStmt binds : stmts )
+ go (LetStmt binds : stmts)
= go stmts `thenDs` \ rest ->
dsLet binds rest
go (BindStmt pat expr locn : stmts)
- = putSrcLocDs locn $
- dsExpr expr `thenDs` \ expr2 ->
+ = go stmts `thenDs` \ body ->
+ putSrcLocDs locn $ -- Rest is associated with this location
+ dsExpr expr `thenDs` \ rhs ->
+ mkStringLit (mk_msg locn) `thenDs` \ core_msg ->
let
- a_ty = outPatType pat
- fail_expr = HsApp (TyApp (HsVar fail_id) [b_ty])
- (HsLit (HsString (mkFastString msg)))
- msg = "Pattern match failure in do expression, " ++ showSDoc (ppr locn)
- main_match = mkSimpleMatch [pat]
- (HsDo do_or_lc stmts ids result_ty locn)
- result_ty locn
- the_matches
- | failureFreePat pat = [main_match]
- | otherwise =
- [ main_match
- , mkSimpleMatch [WildPat a_ty] fail_expr result_ty locn
- ]
+ -- 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
- matchWrapper (DoCtxt do_or_lc) the_matches `thenDs` \ (binders, matching_code) ->
- returnDs (mkApps (Var bind_id) [Type a_ty, Type b_ty, expr2,
- mkLams binders matching_code])
+ 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
- go stmts
+ go stmts `thenDs` \ stmts_code ->
+ returnDs (foldr Let stmts_code meth_binds)
where
do_expr expr locn = putSrcLocDs locn (dsExpr expr)
+ mk_msg locn = "Pattern match failure in do expression at " ++ showSDoc (ppr locn)
\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?)
-
-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.
+Translation for RecStmt's:
+-----------------------------
+We turn (RecStmt [v1,..vn] stmts) into:
+
+ (v1,..,vn) <- mfix (\~(v1,..vn). do stmts
+ return (v1,..vn))
\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)
+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}
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