X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FdeSugar%2FDsListComp.lhs;h=aabd6b0d0d0776ed06632f65f321f55182f9e9b1;hp=1ecab67e10fbc580e8e79d854152c004db1b2b8d;hb=18691d440f90a3dff4ef538091c886af505e5cf5;hpb=4ac2bb39dffb4b825ece73b349ff0d56d79092d7 diff --git a/compiler/deSugar/DsListComp.lhs b/compiler/deSugar/DsListComp.lhs index 1ecab67..aabd6b0 100644 --- a/compiler/deSugar/DsListComp.lhs +++ b/compiler/deSugar/DsListComp.lhs @@ -54,7 +54,9 @@ dsListComp :: [LStmt Id] dsListComp lquals res_ty = do dflags <- getDOptsDs let quals = map unLoc lquals - [elt_ty] = tcTyConAppArgs res_ty + elt_ty = case tcTyConAppArgs res_ty of + [elt_ty] -> elt_ty + _ -> pprPanic "dsListComp" (ppr res_ty $$ ppr lquals) if not (dopt Opt_EnableRewriteRules dflags) || dopt Opt_IgnoreInterfacePragmas dflags -- Either rules are switched off, or we are ignoring what there are; @@ -82,83 +84,61 @@ dsListComp lquals res_ty = do -- of that comprehension that we need in the outer comprehension into such an expression -- and the type of the elements that it outputs (tuples of binders) dsInnerListComp :: ([LStmt Id], [Id]) -> DsM (CoreExpr, Type) -dsInnerListComp (stmts, bndrs) = do +dsInnerListComp (stmts, bndrs) = do { expr <- dsListComp (stmts ++ [noLoc $ mkLastStmt (mkBigLHsVarTup bndrs)]) - bndrs_tuple_type + (mkListTy bndrs_tuple_type) ; return (expr, bndrs_tuple_type) } where bndrs_tuple_type = mkBigCoreVarTupTy bndrs --- This function factors out commonality between the desugaring strategies for TransformStmt. --- Given such a statement it gives you back an expression representing how to compute the transformed --- list and the tuple that you need to bind from that list in order to proceed with your desugaring -dsTransformStmt :: Stmt Id -> DsM (CoreExpr, LPat Id) -dsTransformStmt (TransformStmt stmts binders usingExpr maybeByExpr _ _) - = do { (expr, binders_tuple_type) <- dsInnerListComp (stmts, binders) - ; usingExpr' <- dsLExpr usingExpr - - ; using_args <- - case maybeByExpr of - Nothing -> return [expr] - Just byExpr -> do - byExpr' <- dsLExpr byExpr - - us <- newUniqueSupply - [tuple_binder] <- newSysLocalsDs [binders_tuple_type] - let byExprWrapper = mkTupleCase us binders byExpr' tuple_binder (Var tuple_binder) - - return [Lam tuple_binder byExprWrapper, expr] - - ; let inner_list_expr = mkApps usingExpr' ((Type binders_tuple_type) : using_args) - pat = mkBigLHsVarPatTup binders - ; return (inner_list_expr, pat) } - -- This function factors out commonality between the desugaring strategies for GroupStmt. -- Given such a statement it gives you back an expression representing how to compute the transformed -- list and the tuple that you need to bind from that list in order to proceed with your desugaring -dsGroupStmt :: Stmt Id -> DsM (CoreExpr, LPat Id) -dsGroupStmt (GroupStmt stmts binderMap by using _ _ _) = do - let (fromBinders, toBinders) = unzip binderMap - - fromBindersTypes = map idType fromBinders - toBindersTypes = map idType toBinders - - toBindersTupleType = mkBigCoreTupTy toBindersTypes +dsTransStmt :: Stmt Id -> DsM (CoreExpr, LPat Id) +dsTransStmt (TransStmt { trS_form = form, trS_stmts = stmts, trS_bndrs = binderMap + , trS_by = by, trS_using = using }) = do + let (from_bndrs, to_bndrs) = unzip binderMap + from_bndrs_tys = map idType from_bndrs + to_bndrs_tys = map idType to_bndrs + to_bndrs_tup_ty = mkBigCoreTupTy to_bndrs_tys -- Desugar an inner comprehension which outputs a list of tuples of the "from" binders - (expr, from_tup_ty) <- dsInnerListComp (stmts, fromBinders) + (expr, from_tup_ty) <- dsInnerListComp (stmts, from_bndrs) -- Work out what arguments should be supplied to that expression: i.e. is an extraction -- function required? If so, create that desugared function and add to arguments - usingExpr' <- dsLExpr (either id noLoc using) + usingExpr' <- dsLExpr using usingArgs <- case by of Nothing -> return [expr] Just by_e -> do { by_e' <- dsLExpr by_e - ; us <- newUniqueSupply - ; [from_tup_id] <- newSysLocalsDs [from_tup_ty] - ; let by_wrap = mkTupleCase us fromBinders by_e' - from_tup_id (Var from_tup_id) - ; return [Lam from_tup_id by_wrap, expr] } + ; lam <- matchTuple from_bndrs by_e' + ; return [lam, expr] } -- Create an unzip function for the appropriate arity and element types and find "map" - (unzip_fn, unzip_rhs) <- mkUnzipBind fromBindersTypes + unzip_stuff <- mkUnzipBind form from_bndrs_tys map_id <- dsLookupGlobalId mapName -- Generate the expressions to build the grouped list let -- First we apply the grouping function to the inner list - inner_list_expr = mkApps usingExpr' ((Type from_tup_ty) : usingArgs) + inner_list_expr = mkApps usingExpr' usingArgs -- Then we map our "unzip" across it to turn the lists of tuples into tuples of lists -- We make sure we instantiate the type variable "a" to be a list of "from" tuples and -- the "b" to be a tuple of "to" lists! - unzipped_inner_list_expr = mkApps (Var map_id) - [Type (mkListTy from_tup_ty), Type toBindersTupleType, Var unzip_fn, inner_list_expr] -- Then finally we bind the unzip function around that expression - bound_unzipped_inner_list_expr = Let (Rec [(unzip_fn, unzip_rhs)]) unzipped_inner_list_expr - - -- Build a pattern that ensures the consumer binds into the NEW binders, which hold lists rather than single values - let pat = mkBigLHsVarPatTup toBinders + bound_unzipped_inner_list_expr + = case unzip_stuff of + Nothing -> inner_list_expr + Just (unzip_fn, unzip_rhs) -> Let (Rec [(unzip_fn, unzip_rhs)]) $ + mkApps (Var map_id) $ + [ Type (mkListTy from_tup_ty) + , Type to_bndrs_tup_ty + , Var unzip_fn + , inner_list_expr] + + -- Build a pattern that ensures the consumer binds into the NEW binders, + -- which hold lists rather than single values + let pat = mkBigLHsVarPatTup to_bndrs return (bound_unzipped_inner_list_expr, pat) - \end{code} %************************************************************************ @@ -248,12 +228,8 @@ deListComp (LetStmt binds : quals) list = do core_rest <- deListComp quals list dsLocalBinds binds core_rest -deListComp (stmt@(TransformStmt {}) : quals) list = do - (inner_list_expr, pat) <- dsTransformStmt stmt - deBindComp pat inner_list_expr quals list - -deListComp (stmt@(GroupStmt {}) : quals) list = do - (inner_list_expr, pat) <- dsGroupStmt stmt +deListComp (stmt@(TransStmt {}) : quals) list = do + (inner_list_expr, pat) <- dsTransStmt stmt deBindComp pat inner_list_expr quals list deListComp (BindStmt pat list1 _ _ : quals) core_list2 = do -- rule A' above @@ -261,16 +237,14 @@ deListComp (BindStmt pat list1 _ _ : quals) core_list2 = do -- rule A' above deBindComp pat core_list1 quals core_list2 deListComp (ParStmt stmtss_w_bndrs _ _ _ : quals) list - = do - exps_and_qual_tys <- mapM dsInnerListComp stmtss_w_bndrs - let (exps, qual_tys) = unzip exps_and_qual_tys + = do { exps_and_qual_tys <- mapM dsInnerListComp stmtss_w_bndrs + ; let (exps, qual_tys) = unzip exps_and_qual_tys - (zip_fn, zip_rhs) <- mkZipBind qual_tys + ; (zip_fn, zip_rhs) <- mkZipBind qual_tys -- Deal with [e | pat <- zip l1 .. ln] in example above - deBindComp pat (Let (Rec [(zip_fn, zip_rhs)]) (mkApps (Var zip_fn) exps)) - quals list - + ; deBindComp pat (Let (Rec [(zip_fn, zip_rhs)]) (mkApps (Var zip_fn) exps)) + quals list } where bndrs_s = map snd stmtss_w_bndrs @@ -358,13 +332,8 @@ dfListComp c_id n_id (LetStmt binds : quals) = do core_rest <- dfListComp c_id n_id quals dsLocalBinds binds core_rest -dfListComp c_id n_id (stmt@(TransformStmt {}) : quals) = do - (inner_list_expr, pat) <- dsTransformStmt stmt - -- Anyway, we bind the newly transformed list via the generic binding function - dfBindComp c_id n_id (pat, inner_list_expr) quals - -dfListComp c_id n_id (stmt@(GroupStmt {}) : quals) = do - (inner_list_expr, pat) <- dsGroupStmt stmt +dfListComp c_id n_id (stmt@(TransStmt {}) : quals) = do + (inner_list_expr, pat) <- dsTransStmt stmt -- Anyway, we bind the newly grouped list via the generic binding function dfBindComp c_id n_id (pat, inner_list_expr) quals @@ -442,7 +411,7 @@ mkZipBind elt_tys = do -- Increasing order of tag -mkUnzipBind :: [Type] -> DsM (Id, CoreExpr) +mkUnzipBind :: TransForm -> [Type] -> DsM (Maybe (Id, CoreExpr)) -- mkUnzipBind [t1, t2] -- = (unzip, \ys :: [(t1, t2)] -> foldr (\ax :: (t1, t2) axs :: ([t1], [t2]) -- -> case ax of @@ -452,28 +421,29 @@ mkUnzipBind :: [Type] -> DsM (Id, CoreExpr) -- ys) -- -- We use foldr here in all cases, even if rules are turned off, because we may as well! -mkUnzipBind elt_tys = do - ax <- newSysLocalDs elt_tuple_ty - axs <- newSysLocalDs elt_list_tuple_ty - ys <- newSysLocalDs elt_tuple_list_ty - xs <- mapM newSysLocalDs elt_tys - xss <- mapM newSysLocalDs elt_list_tys +mkUnzipBind ThenForm _ + = return Nothing -- No unzipping for ThenForm +mkUnzipBind _ elt_tys + = do { ax <- newSysLocalDs elt_tuple_ty + ; axs <- newSysLocalDs elt_list_tuple_ty + ; ys <- newSysLocalDs elt_tuple_list_ty + ; xs <- mapM newSysLocalDs elt_tys + ; xss <- mapM newSysLocalDs elt_list_tys - unzip_fn <- newSysLocalDs unzip_fn_ty - - [us1, us2] <- sequence [newUniqueSupply, newUniqueSupply] - - let nil_tuple = mkBigCoreTup (map mkNilExpr elt_tys) - - concat_expressions = map mkConcatExpression (zip3 elt_tys (map Var xs) (map Var xss)) - tupled_concat_expression = mkBigCoreTup concat_expressions - - folder_body_inner_case = mkTupleCase us1 xss tupled_concat_expression axs (Var axs) - folder_body_outer_case = mkTupleCase us2 xs folder_body_inner_case ax (Var ax) - folder_body = mkLams [ax, axs] folder_body_outer_case - - unzip_body <- mkFoldrExpr elt_tuple_ty elt_list_tuple_ty folder_body nil_tuple (Var ys) - return (unzip_fn, mkLams [ys] unzip_body) + ; unzip_fn <- newSysLocalDs unzip_fn_ty + + ; [us1, us2] <- sequence [newUniqueSupply, newUniqueSupply] + + ; let nil_tuple = mkBigCoreTup (map mkNilExpr elt_tys) + concat_expressions = map mkConcatExpression (zip3 elt_tys (map Var xs) (map Var xss)) + tupled_concat_expression = mkBigCoreTup concat_expressions + + folder_body_inner_case = mkTupleCase us1 xss tupled_concat_expression axs (Var axs) + folder_body_outer_case = mkTupleCase us2 xs folder_body_inner_case ax (Var ax) + folder_body = mkLams [ax, axs] folder_body_outer_case + + ; unzip_body <- mkFoldrExpr elt_tuple_ty elt_list_tuple_ty folder_body nil_tuple (Var ys) + ; return (Just (unzip_fn, mkLams [ys] unzip_body)) } where elt_tuple_ty = mkBigCoreTupTy elt_tys elt_tuple_list_ty = mkListTy elt_tuple_ty @@ -688,45 +658,15 @@ parrElemType e = Translation for monad comprehensions \begin{code} - --- | Keep the "context" of a monad comprehension in a small data type to avoid --- some boilerplate... -data DsMonadComp = DsMonadComp - { mc_return :: Either (SyntaxExpr Id) (Expr CoreBndr) - , mc_body :: LHsExpr Id - , mc_m_ty :: Type - } - --- -- Entry point for monad comprehension desugaring --- -dsMonadComp :: [LStmt Id] -- the statements - -> Type -- the final type - -> DsM CoreExpr -dsMonadComp stmts res_ty - = dsMcStmts stmts (DsMonadComp (Left return_op) body m_ty) - where - (m_ty, _) = tcSplitAppTy res_ty - - -dsMcStmts :: [LStmt Id] - -> DsMonadComp - -> DsM CoreExpr - --- No statements left for desugaring. Desugar the body after calling "return" --- on it. -dsMcStmts [] DsMonadComp { mc_return, mc_body } - = case mc_return of - Left ret -> dsLExpr $ noLoc ret `nlHsApp` mc_body - Right ret' -> do - { body' <- dsLExpr mc_body - ; return $ mkApps ret' [body'] } - --- Otherwise desugar each statement step by step -dsMcStmts ((L loc stmt) : lstmts) mc - = putSrcSpanDs loc (dsMcStmt stmt lstmts mc) +dsMonadComp :: [LStmt Id] -> DsM CoreExpr +dsMonadComp stmts = dsMcStmts stmts +dsMcStmts :: [LStmt Id] -> DsM CoreExpr +dsMcStmts [] = panic "dsMcStmts" +dsMcStmts (L loc stmt : lstmts) = putSrcSpanDs loc (dsMcStmt stmt lstmts) +--------------- dsMcStmt :: Stmt Id -> [LStmt Id] -> DsM CoreExpr dsMcStmt (LastStmt body ret_op) stmts @@ -757,35 +697,11 @@ dsMcStmt (ExprStmt exp then_exp guard_exp _) stmts ; return $ mkApps then_exp' [ mkApps guard_exp' [exp'] , rest ] } --- Transform statements desugar like this: --- --- [ .. | qs, then f by e ] -> f (\q_v -> e) [| qs |] --- --- where [| qs |] is the desugared inner monad comprehenion generated by the --- statements `qs`. -dsMcStmt (TransformStmt stmts binders usingExpr maybeByExpr return_op bind_op) stmts_rest - = do { expr <- dsInnerMonadComp stmts binders return_op - ; let binders_tup_type = mkBigCoreTupTy $ map idType binders - ; usingExpr' <- dsLExpr usingExpr - ; using_args <- case maybeByExpr of - Nothing -> return [expr] - Just byExpr -> do - byExpr' <- dsLExpr byExpr - us <- newUniqueSupply - tup_binder <- newSysLocalDs binders_tup_type - let byExprWrapper = mkTupleCase us binders byExpr' tup_binder (Var tup_binder) - return [Lam tup_binder byExprWrapper, expr] - - ; let pat = mkBigLHsVarPatTup binders - rhs = mkApps usingExpr' ((Type binders_tup_type) : using_args) - - ; dsMcBindStmt pat rhs bind_op noSyntaxExpr stmts_rest } - -- Group statements desugar like this: -- -- [| (q, then group by e using f); rest |] -- ---> f {qt} (\qv -> e) [| q; return qv |] >>= \ n_tup -> --- case unzip n_tup of qv -> [| rest |] +-- case unzip n_tup of qv' -> [| rest |] -- -- where variables (v1:t1, ..., vk:tk) are bound by q -- qv = (v1, ..., vk) @@ -794,61 +710,41 @@ dsMcStmt (TransformStmt stmts binders usingExpr maybeByExpr return_op bind_op) s -- f :: forall a. (a -> t) -> m1 a -> m2 (n a) -- n_tup :: n qt -- unzip :: n qt -> (n t1, ..., n tk) (needs Functor n) --- --- [| q, then group by e using f |] -> (f (\q_v -> e) [| q |]) >>= (return . (unzip q_v)) --- --- which is equal to --- --- [| q, then group by e using f |] -> liftM (unzip q_v) (f (\q_v -> e) [| q |]) --- --- where unzip is of the form --- --- unzip :: n (a,b,c,..) -> (n a,n b,n c,..) --- unzip m_tuple = ( fmap selN1 m_tuple --- , fmap selN2 m_tuple --- , .. ) --- where selN1 (a,b,c,..) = a --- selN2 (a,b,c,..) = b --- .. --- -dsMcStmt (GroupStmt stmts binderMap by using return_op bind_op fmap_op) stmts_rest - = do { let (fromBinders, toBinders) = unzip binderMap - fromBindersTypes = map idType fromBinders -- Types ty - fromBindersTupleTy = mkBigCoreTupTy fromBindersTypes - toBindersTypes = map idType toBinders -- Types (n ty) - toBindersTupleTy = mkBigCoreTupTy toBindersTypes + +dsMcStmt (TransStmt { trS_stmts = stmts, trS_bndrs = bndrs + , trS_by = by, trS_using = using + , trS_ret = return_op, trS_bind = bind_op + , trS_fmap = fmap_op, trS_form = form }) stmts_rest + = do { let (from_bndrs, to_bndrs) = unzip bndrs + from_bndr_tys = map idType from_bndrs -- Types ty -- Desugar an inner comprehension which outputs a list of tuples of the "from" binders - ; expr <- dsInnerMonadComp stmts fromBinders return_op + ; expr <- dsInnerMonadComp stmts from_bndrs return_op -- Work out what arguments should be supplied to that expression: i.e. is an extraction -- function required? If so, create that desugared function and add to arguments - ; usingExpr' <- dsLExpr (either id noLoc using) + ; usingExpr' <- dsLExpr using ; usingArgs <- case by of Nothing -> return [expr] Just by_e -> do { by_e' <- dsLExpr by_e - ; lam <- matchTuple fromBinders by_e' + ; lam <- matchTuple from_bndrs by_e' ; return [lam, expr] } - -- Create an unzip function for the appropriate arity and element types - ; fmap_op' <- dsExpr fmap_op - ; (unzip_fn, unzip_rhs) <- mkMcUnzipM fmap_op' m_ty fromBindersTypes - -- Generate the expressions to build the grouped list -- Build a pattern that ensures the consumer binds into the NEW binders, -- which hold monads rather than single values ; bind_op' <- dsExpr bind_op - ; let bind_ty = exprType bind_op' -- m2 (n (a,b,c)) -> (n (a,b,c) -> r1) -> r2 - n_tup_ty = funArgTy $ funArgTy $ funResultTy bind_ty - - ; body <- dsMcStmts stmts_rest - ; n_tup_var <- newSysLocalDs n_tup_ty - ; tup_n_var <- newSysLocalDs (mkBigCoreVarTupTy toBinders) - ; us <- newUniqueSupply - ; let unzip_n_tup = Let (Rec [(unzip_fn, unzip_rhs)]) $ - App (Var unzip_fn) (Var n_tup_var) - -- unzip_n_tup :: (n a, n b, n c) - body' = mkTupleCase us toBinders body unzip_n_tup (Var tup_n_var) + ; let bind_ty = exprType bind_op' -- m2 (n (a,b,c)) -> (n (a,b,c) -> r1) -> r2 + n_tup_ty = funArgTy $ funArgTy $ funResultTy bind_ty -- n (a,b,c) + tup_n_ty = mkBigCoreVarTupTy to_bndrs + + ; body <- dsMcStmts stmts_rest + ; n_tup_var <- newSysLocalDs n_tup_ty + ; tup_n_var <- newSysLocalDs tup_n_ty + ; tup_n_expr <- mkMcUnzipM form fmap_op n_tup_var from_bndr_tys + ; us <- newUniqueSupply + ; let rhs' = mkApps usingExpr' usingArgs + body' = mkTupleCase us to_bndrs body tup_n_var tup_n_expr ; return (mkApps bind_op' [rhs', Lam n_tup_var body']) } @@ -864,23 +760,26 @@ dsMcStmt (GroupStmt stmts binderMap by using return_op bind_op fmap_op) stmts_re -- NB: we need a polymorphic mzip because we call it several times dsMcStmt (ParStmt pairs mzip_op bind_op return_op) stmts_rest - = do { exps <- mapM ds_inner pairs - ; let qual_tys = map (mkBigCoreVarTupTy . snd) pairs - ; mzip_op' <- dsExpr mzip_op - ; (zip_fn, zip_rhs) <- mkMcZipM mzip_op' (mc_m_ty mc) qual_tys + = do { exps_w_tys <- mapM ds_inner pairs -- Pairs (exp :: m ty, ty) + ; mzip_op' <- dsExpr mzip_op ; let -- The pattern variables - vars = map (mkBigLHsVarPatTup . snd) pairs + pats = map (mkBigLHsVarPatTup . snd) pairs -- Pattern with tuples of variables -- [v1,v2,v3] => (v1, (v2, v3)) - pat = foldr (\tn tm -> mkBigLHsPatTup [tn, tm]) (last vars) (init vars) - rhs = Let (Rec [(zip_fn, zip_rhs)]) (mkApps (Var zip_fn) exps) + pat = foldr1 (\p1 p2 -> mkLHsPatTup [p1, p2]) pats + (rhs, _) = foldr1 (\(e1,t1) (e2,t2) -> + (mkApps mzip_op' [Type t1, Type t2, e1, e2], + mkBoxedTupleTy [t1,t2])) + exps_w_tys ; dsMcBindStmt pat rhs bind_op noSyntaxExpr stmts_rest } where - ds_inner (stmts, bndrs) = dsInnerMonadComp stmts bndrs mono_ret_op + ds_inner (stmts, bndrs) = do { exp <- dsInnerMonadComp stmts bndrs mono_ret_op + ; return (exp, tup_ty) } where - mono_ret_op = HsWrap (WpTyApp (mkBigCoreVarTupTy bndrs)) return_op + mono_ret_op = HsWrap (WpTyApp tup_ty) return_op + tup_ty = mkBigCoreVarTupTy bndrs dsMcStmt stmt _ = pprPanic "dsMcStmt: unexpected stmt" (ppr stmt) @@ -891,10 +790,9 @@ matchTuple :: [Id] -> CoreExpr -> DsM CoreExpr -- \x. case x of (a,b,c) -> body matchTuple ids body = do { us <- newUniqueSupply - ; tup_id <- newSysLocalDs (mkBigLHsVarPatTup ids) + ; tup_id <- newSysLocalDs (mkBigCoreVarTupTy ids) ; return (Lam tup_id $ mkTupleCase us ids body tup_id (Var tup_id)) } - -- general `rhs' >>= \pat -> stmts` desugaring where `rhs'` is already a -- desugared `CoreExpr` dsMcBindStmt :: LPat Id @@ -936,10 +834,10 @@ dsMcBindStmt pat rhs' bind_op fail_op stmts dsInnerMonadComp :: [LStmt Id] -> [Id] -- Return a tuple of these variables - -> LHsExpr Id -- The monomorphic "return" operator + -> HsExpr Id -- The monomorphic "return" operator -> DsM CoreExpr dsInnerMonadComp stmts bndrs ret_op - = dsMcStmts (stmts ++ [noLoc (ReturnStmt (mkBigLHsVarTup bndrs) ret_op)]) + = dsMcStmts (stmts ++ [noLoc (LastStmt (mkBigLHsVarTup bndrs) ret_op)]) -- The `unzip` function for `GroupStmt` in a monad comprehensions -- @@ -948,85 +846,30 @@ dsInnerMonadComp stmts bndrs ret_op -- , liftM selN2 m_tuple -- , .. ) -- --- mkMcUnzipM m [t1, t2] --- = (unzip_fn, \ys :: m (t1, t2) -> --- ( liftM (selN1 :: (t1, t2) -> t1) ys --- , liftM (selN2 :: (t1, t2) -> t2) ys --- )) --- -mkMcUnzipM :: CoreExpr - -> Type -- m - -> [Type] -- [a,b,c,..] - -> DsM (Id, CoreExpr) -mkMcUnzipM liftM_op m_ty elt_tys - = do { ys <- newSysLocalDs monad_tuple_ty - ; xs <- mapM newSysLocalDs elt_tys - ; scrut <- newSysLocalDs tuple_tys - - ; unzip_fn <- newSysLocalDs unzip_fn_ty - - ; let -- Select one Id from our tuple - selectExpr n = mkLams [scrut] $ mkTupleSelector xs (xs !! n) scrut (Var scrut) - -- Apply 'selectVar' and 'ys' to 'liftM' - tupleElem n = mkApps liftM_op - -- Types (m is figured out by the type checker): - -- liftM :: forall a b. (a -> b) -> m a -> m b - [ Type tuple_tys, Type (elt_tys !! n) - -- Arguments: - , selectExpr n, Var ys ] - -- The final expression with the big tuple - unzip_body = mkBigCoreTup [ tupleElem n | n <- [0..length elt_tys - 1] ] - - ; return (unzip_fn, mkLams [ys] unzip_body) } - where monad_tys = map (m_ty `mkAppTy`) elt_tys -- [m a,m b,m c,..] - tuple_monad_tys = mkBigCoreTupTy monad_tys -- (m a,m b,m c,..) - tuple_tys = mkBigCoreTupTy elt_tys -- (a,b,c,..) - monad_tuple_ty = m_ty `mkAppTy` tuple_tys -- m (a,b,c,..) - unzip_fn_ty = monad_tuple_ty `mkFunTy` tuple_monad_tys -- m (a,b,c,..) -> (m a,m b,m c,..) - --- Generate the `mzip` function for `ParStmt` in monad comprehensions, for --- example: --- --- mzip :: m t1 --- -> (m t2 -> m t3 -> m (t2, t3)) --- -> m (t1, (t2, t3)) --- --- mkMcZipM m [t1, t2, t3] --- = (zip_fn, \(q1::t1) (q2::t2) (q3::t3) -> --- mzip q1 (mzip q2 q3)) --- -mkMcZipM :: CoreExpr - -> Type - -> [Type] - -> DsM (Id, CoreExpr) - -mkMcZipM mzip_op m_ty tys@(_:_:_) -- min. 2 types - = do { (ids, t1, tuple_ty, zip_body) <- loop tys - ; zip_fn <- newSysLocalDs $ - (m_ty `mkAppTy` t1) - `mkFunTy` - (m_ty `mkAppTy` tuple_ty) - `mkFunTy` - (m_ty `mkAppTy` mkBigCoreTupTy [t1, tuple_ty]) - ; return (zip_fn, mkLams ids zip_body) } - - where - -- loop :: [Type] -> DsM ([Id], Type, [Type], CoreExpr) - loop [t1, t2] = do -- last run of the `loop` - { ids@[a,b] <- newSysLocalsDs (map (m_ty `mkAppTy`) [t1,t2]) - ; let zip_body = mkApps mzip_op [ Type t1, Type t2 , Var a, Var b ] - ; return (ids, t1, t2, zip_body) } - - loop (t1:tr) = do - { -- Get ty, ids etc from the "inner" zip - (ids', t1', t2', zip_body') <- loop tr - - ; a <- newSysLocalDs $ m_ty `mkAppTy` t1 - ; let tuple_ty' = mkBigCoreTupTy [t1', t2'] - zip_body = mkApps mzip_op [ Type t1, Type tuple_ty', Var a, zip_body' ] - ; return ((a:ids'), t1, tuple_ty', zip_body) } - --- This case should never happen: -mkMcZipM _ _ tys = pprPanic "mkMcZipM: unexpected argument" (ppr tys) - +-- mkMcUnzipM fmap ys [t1, t2] +-- = ( fmap (selN1 :: (t1, t2) -> t1) ys +-- , fmap (selN2 :: (t1, t2) -> t2) ys ) + +mkMcUnzipM :: TransForm + -> SyntaxExpr TcId -- fmap + -> Id -- Of type n (a,b,c) + -> [Type] -- [a,b,c] + -> DsM CoreExpr -- Of type (n a, n b, n c) +mkMcUnzipM ThenForm _ ys _ + = return (Var ys) -- No unzipping to do + +mkMcUnzipM _ fmap_op ys elt_tys + = do { fmap_op' <- dsExpr fmap_op + ; xs <- mapM newSysLocalDs elt_tys + ; let tup_ty = mkBigCoreTupTy elt_tys + ; tup_xs <- newSysLocalDs tup_ty + + ; let mk_elt i = mkApps fmap_op' -- fmap :: forall a b. (a -> b) -> n a -> n b + [ Type tup_ty, Type (elt_tys !! i) + , mk_sel i, Var ys] + + mk_sel n = Lam tup_xs $ + mkTupleSelector xs (xs !! n) tup_xs (Var tup_xs) + + ; return (mkBigCoreTup (map mk_elt [0..length elt_tys - 1])) } \end{code}