import DsGRHSs ( dsGuarded )
import DsCCall ( dsCCall )
import DsListComp ( dsListComp, dsPArrComp )
-import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr)
+import DsUtils ( mkErrorAppDs, mkStringLit, mkConsExpr, mkNilExpr, selectMatchVar )
import DsMonad
#ifdef GHCI
-- Template Haskell stuff iff bootstrapped
-import DsMeta ( dsBracket )
+import DsMeta ( dsBracket, dsReify )
#endif
-import HsSyn ( failureFreePat,
- HsExpr(..), Pat(..), HsLit(..), ArithSeqInfo(..),
- Stmt(..), HsMatchContext(..), HsDoContext(..),
+import HsSyn ( HsExpr(..), Pat(..), HsLit(..), ArithSeqInfo(..),
+ Stmt(..), HsMatchContext(..), HsStmtContext(..),
Match(..), HsBinds(..), MonoBinds(..), HsConDetails(..),
- mkSimpleMatch
+ mkSimpleMatch, isDoExpr
)
import TcHsSyn ( TypecheckedHsExpr, TypecheckedHsBinds, TypecheckedStmt, hsPatType )
-- Sigh. This is a pain.
import TcType ( tcSplitAppTy, tcSplitFunTys, tcTyConAppArgs,
- tcSplitTyConApp, isUnLiftedType, Type )
+ tcSplitTyConApp, isUnLiftedType, Type,
+ mkAppTy )
import Type ( splitFunTys )
import CoreSyn
+import Literal ( Literal(..) )
import CoreUtils ( exprType, mkIfThenElse, bindNonRec )
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 Name ( Name )
import TyCon ( tyConDataCons )
-import TysWiredIn ( tupleCon )
+import TysWiredIn ( tupleCon, mkTupleTy )
import BasicTypes ( RecFlag(..), Boxity(..), ipNameName )
import PrelNames ( toPName )
+import SrcLoc ( noSrcLoc )
import Util ( zipEqual, zipWithEqual )
import Outputable
import FastString
= 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)
= 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
#ifdef GHCI /* Only if bootstrapping */
dsExpr (HsBracketOut x ps) = dsBracket x ps
-dsExpr (HsSplice n e) = pprPanic "dsExpr:splice" (ppr e)
+dsExpr (HsReify r) = dsReify r
+dsExpr (HsSplice n e _) = pprPanic "dsExpr:splice" (ppr e)
#endif
\end{code}
Basically does the translation given in the Haskell~1.3 report:
\begin{code}
-dsDo :: HsDoContext
+dsDo :: HsStmtContext Name
-> [TypecheckedStmt]
- -> [Id] -- id for: [return,fail,>>=,>>]
+ -> [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
+dsDo do_or_lc stmts ids 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
+ (return_id : fail_id : bind_id : then_id : _) = ids
+ (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!
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
+ -- In a do expression, pattern-match failure just calls
+ -- the monadic 'fail' rather than throwing an exception
+ fail_expr = mkApps (Var fail_id) [Type b_ty, core_msg]
a_ty = hsPatType 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
- 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 (Var bind_id) [Type a_ty, Type b_ty, rhs, Lam var match_code])
+
+ go (RecStmt rec_vars rec_stmts rec_rets : stmts)
+ = go (bind_stmt : stmts)
+ where
+ bind_stmt = dsRecStmt m_ty ids rec_vars rec_stmts rec_rets
+
in
go stmts
where
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}
+dsRecStmt :: Type -- Monad type constructor :: * -> *
+ -> [Id] -- Ids for: [return,fail,>>=,>>,mfix]
+ -> [Id] -> [TypecheckedStmt] -> [TypecheckedHsExpr] -- Guts of the RecStmt
+ -> TypecheckedStmt
+dsRecStmt m_ty ids@[return_id, _, _, _, mfix_id] vars stmts rets
+ = ASSERT( length vars == length rets )
+ BindStmt tup_pat mfix_app noSrcLoc
+ where
+ (var1:rest) = vars -- Always at least one
+ (ret1:_) = 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 | one_var = idType var1
+ | otherwise = mkTupleTy Boxed (length vars) (map idType vars)
+ tup_pat | one_var = VarPat var1
+ | otherwise = LazyPat (TuplePat (map VarPat vars) Boxed)
+
+ body = HsDo DoExpr (stmts ++ [return_stmt])
+ ids -- Don't need the mfix, but it does no harm
+ (mkAppTy m_ty tup_ty)
+ noSrcLoc
+
+ return_stmt = ResultStmt return_app noSrcLoc
+ return_app = HsApp (TyApp (HsVar return_id) [tup_ty]) tup_expr
\end{code}
projects / ghc-hetmet.git / blobdiff