[Git][ghc/ghc][wip/T24880] Deleted 1 commit: Replace fold/build by stream fusion WIP
Jaro Reinders (@jaro)
gitlab at gitlab.haskell.org
Tue Jun 4 12:57:57 UTC 2024
Jaro Reinders pushed to branch wip/T24880 at Glasgow Haskell Compiler / GHC
WARNING: The push did not contain any new commits, but force pushed to delete the commits and changes below.
Deleted commits:
3e0b4233 by Jaro Reinders at 2024-06-04T14:55:12+02:00
Replace fold/build by stream fusion WIP
- - - - -
10 changed files:
- compiler/GHC/Builtin/Names.hs
- compiler/GHC/Core/Make.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/HsToCore/ListComp.hs
- libraries/ghc-internal/src/GHC/Internal/Base.hs
- libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs
- libraries/ghc-internal/src/GHC/Internal/Enum.hs
- libraries/ghc-internal/src/GHC/Internal/IO/Handle/FD.hs
- libraries/ghc-internal/src/GHC/Internal/List.hs
- libraries/ghc-internal/src/GHC/Internal/System/Posix/Internals.hs
Changes:
=====================================
compiler/GHC/Builtin/Names.hs
=====================================
@@ -356,6 +356,7 @@ basicKnownKeyNames
-- List operations
concatName, filterName, mapName,
zipName, foldrName, buildName, augmentName, appendName,
+ concatMapName,
-- FFI primitive types that are not wired-in.
stablePtrTyConName, ptrTyConName, funPtrTyConName, constPtrConName,
@@ -746,13 +747,14 @@ map_RDR, append_RDR :: RdrName
map_RDR = nameRdrName mapName
append_RDR = nameRdrName appendName
-foldr_RDR, build_RDR, returnM_RDR, bindM_RDR, failM_RDR
+foldr_RDR, build_RDR, returnM_RDR, bindM_RDR, failM_RDR, concatMap_RDR
:: RdrName
foldr_RDR = nameRdrName foldrName
build_RDR = nameRdrName buildName
returnM_RDR = nameRdrName returnMName
bindM_RDR = nameRdrName bindMName
failM_RDR = nameRdrName failMName
+concatMap_RDR = nameRdrName concatMapName
left_RDR, right_RDR :: RdrName
left_RDR = nameRdrName leftDataConName
@@ -1123,7 +1125,7 @@ considerAccessibleName = varQual gHC_INTERNAL_EXTS (fsLit "considerAccessible")
-- Random GHC.Internal.Base functions
fromStringName, otherwiseIdName, foldrName, buildName, augmentName,
- mapName, appendName, assertName,
+ mapName, concatMapName, appendName, assertName,
dollarName :: Name
dollarName = varQual gHC_INTERNAL_BASE (fsLit "$") dollarIdKey
otherwiseIdName = varQual gHC_INTERNAL_BASE (fsLit "otherwise") otherwiseIdKey
@@ -1131,6 +1133,7 @@ foldrName = varQual gHC_INTERNAL_BASE (fsLit "foldr") foldrIdKey
buildName = varQual gHC_INTERNAL_BASE (fsLit "build") buildIdKey
augmentName = varQual gHC_INTERNAL_BASE (fsLit "augment") augmentIdKey
mapName = varQual gHC_INTERNAL_BASE (fsLit "map") mapIdKey
+concatMapName = varQual gHC_INTERNAL_BASE (fsLit "concatMap") concatMapIdKey
appendName = varQual gHC_INTERNAL_BASE (fsLit "++") appendIdKey
assertName = varQual gHC_INTERNAL_BASE (fsLit "assert") assertIdKey
fromStringName = varQual gHC_INTERNAL_DATA_STRING (fsLit "fromString") fromStringClassOpKey
@@ -2376,6 +2379,9 @@ leftSectionKey, rightSectionKey :: Unique
leftSectionKey = mkPreludeMiscIdUnique 45
rightSectionKey = mkPreludeMiscIdUnique 46
+concatMapIdKey :: Unique
+concatMapIdKey = mkPreludeMiscIdUnique 47
+
rootMainKey, runMainKey :: Unique
rootMainKey = mkPreludeMiscIdUnique 101
runMainKey = mkPreludeMiscIdUnique 102
=====================================
compiler/GHC/Core/Make.hs
=====================================
@@ -37,7 +37,7 @@ module GHC.Core.Make (
-- * Constructing list expressions
mkNilExpr, mkConsExpr, mkListExpr,
- mkFoldrExpr, mkBuildExpr,
+ mkFoldrExpr, mkBuildExpr, mkConcatMapExpr,
-- * Constructing Maybe expressions
mkNothingExpr, mkJustExpr,
@@ -796,6 +796,11 @@ mkFoldrExpr elt_ty result_ty c n list = do
`App` n
`App` list)
+mkConcatMapExpr :: MonadThings m => Type -> Type -> CoreExpr -> CoreExpr -> m CoreExpr
+mkConcatMapExpr src_ty tgt_ty f xs = do
+ concatMap_id <- lookupId concatMapName
+ return (Var concatMap_id `App` Type src_ty `App` Type tgt_ty `App` f `App` xs)
+
-- | Make a 'build' expression applied to a locally-bound worker function
mkBuildExpr :: (MonadFail m, MonadThings m, MonadUnique m)
=> Type -- ^ Type of list elements to be built
=====================================
compiler/GHC/Core/Rules.hs
=====================================
@@ -56,7 +56,7 @@ import GHC.Core.Ppr ( pprRules )
import GHC.Core.Unify as Unify ( ruleMatchTyKiX )
import GHC.Core.Type as Type
( Type, extendTvSubst, extendCvSubst
- , substTy, getTyVar_maybe )
+ , substTy, getTyVar_maybe, tyCoVarsOfType )
import GHC.Core.TyCo.Ppr( pprParendType )
import GHC.Core.Coercion as Coercion
import GHC.Core.Tidy ( tidyRules )
@@ -696,12 +696,16 @@ matchRule opts rule_env _is_active fn args _rough_args
Nothing -> Nothing
Just expr -> Just expr
-matchRule _ rule_env is_active _ args rough_args
+matchRule _ rule_env is_active _fn args rough_args
(Rule { ru_name = rule_name, ru_act = act, ru_rough = tpl_tops
, ru_bndrs = tpl_vars, ru_args = tpl_args, ru_rhs = rhs })
| not (is_active act) = Nothing
| ruleCantMatch tpl_tops rough_args = Nothing
- | otherwise = matchN rule_env rule_name tpl_vars tpl_args args rhs
+ | otherwise =
+ case matchN rule_env rule_name tpl_vars tpl_args args rhs of
+ Just x -> -- pprTrace "match found:" (ppr rule_name <+> ppr _fn <+> ppr args) True
+ Just x
+ Nothing -> Nothing
---------------------------------------
@@ -1046,9 +1050,9 @@ tryFloatIn :: CoreExpr -> Maybe CoreExpr
tryFloatIn = go emptyVarSet False id where
go vs _ c (Let bind e) = go (extendVarSetList vs (bindersOf bind)) True (c . Let bind) e
go vs _ c (Case scrut case_bndr ty [Alt con alt_bndrs rhs]) = go (extendVarSetList vs alt_bndrs) True (c . (\x -> Case scrut case_bndr (exprType x) [Alt con alt_bndrs x])) rhs
- go vs True c (App e1 e2) = App <$> go vs True c e1 <*> pure (c e2)
- go vs True c e@(Var v) | not (v `elemVarSet` vs) = Just e
- go vs True _ e at Type{} = Just e
+ go vs True c (App e1 e2) = App <$> go vs True c e1 <*> Just (c e2)
+ go vs True _ e@(Var v) | not (v `elemVarSet` vs) = Just e
+ go vs True _ e@(Type ty) | isEmptyVarSet (tyCoVarsOfType ty `intersectVarSet` vs) = Just e
go vs True _ e at Lit{} = Just e
go _ _ _ _ = Nothing
=====================================
compiler/GHC/HsToCore/ListComp.hs
=====================================
@@ -61,7 +61,7 @@ dsListComp lquals res_ty = do
|| isParallelComp quals
-- Foldr-style desugaring can't handle parallel list comprehensions
then deListComp quals (mkNilExpr elt_ty)
- else mkBuildExpr elt_ty (\(c, _) (n, _) -> dfListComp c n quals)
+ else dfListComp elt_ty quals
-- Foldr/build should be enabled, so desugar
-- into foldrs and builds
@@ -305,78 +305,73 @@ deBindComp pat core_list1 quals core_list2 = do
@dfListComp@ are the rules used with foldr/build turned on:
\begin{verbatim}
-TE[ e | ] c n = c e n
-TE[ e | b , q ] c n = if b then TE[ e | q ] c n else n
-TE[ e | p <- l , q ] c n = let
- f = \ x b -> case x of
- p -> TE[ e | q ] c b
- _ -> b
- in
- foldr f n l
+TE[ e | ] = [e]
+TE[ e | b , q ] = if b then TE[ e | q ] else []
+TE[ e | p <- l , q ] = concatMap (\x -> case x of
+ p -> TE[ e | q ]
+ _ -> []) l
\end{verbatim}
-}
-dfListComp :: Id -> Id -- 'c' and 'n'
+dfListComp :: Type -- element type
-> [ExprStmt GhcTc] -- the rest of the qual's
-> DsM CoreExpr
-dfListComp _ _ [] = panic "dfListComp"
+dfListComp _ [] = panic "dfListComp"
-dfListComp c_id n_id (LastStmt _ body _ _ : quals)
+dfListComp elt_ty (LastStmt _ body _ _ : quals)
= assert (null quals) $
do { core_body <- dsLExpr body
- ; return (mkApps (Var c_id) [core_body, Var n_id]) }
+ ; return (mkListExpr elt_ty [core_body]) }
-- Non-last: must be a guard
-dfListComp c_id n_id (BodyStmt _ guard _ _ : quals) = do
+dfListComp elt_ty (BodyStmt _ guard _ _ : quals) = do
core_guard <- dsLExpr guard
- core_rest <- dfListComp c_id n_id quals
- return (mkIfThenElse core_guard core_rest (Var n_id))
+ core_rest <- dfListComp elt_ty quals
+ return (mkIfThenElse core_guard core_rest (mkListExpr elt_ty []))
-dfListComp c_id n_id (LetStmt _ binds : quals) = do
+dfListComp elt_ty (LetStmt _ binds : quals) = do
-- new in 1.3, local bindings
- core_rest <- dfListComp c_id n_id quals
+ core_rest <- dfListComp elt_ty quals
dsLocalBinds binds core_rest
-dfListComp c_id n_id (stmt@(TransStmt {}) : quals) = do
+dfListComp elt_ty (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
+ dfBindComp elt_ty (pat, inner_list_expr) quals
-dfListComp c_id n_id (BindStmt _ pat list1 : quals) = do
+dfListComp elt_ty (BindStmt _ pat list1 : quals) = do
-- evaluate the two lists
core_list1 <- dsLExpr list1
-- Do the rest of the work in the generic binding builder
- dfBindComp c_id n_id (pat, core_list1) quals
+ dfBindComp elt_ty (pat, core_list1) quals
-dfListComp _ _ (ParStmt {} : _) = panic "dfListComp ParStmt"
-dfListComp _ _ (RecStmt {} : _) = panic "dfListComp RecStmt"
-dfListComp _ _ (XStmtLR ApplicativeStmt {} : _) =
+dfListComp _ (ParStmt {} : _) = panic "dfListComp ParStmt"
+dfListComp _ (RecStmt {} : _) = panic "dfListComp RecStmt"
+dfListComp _ (XStmtLR ApplicativeStmt {} : _) =
panic "dfListComp ApplicativeStmt"
-dfBindComp :: Id -> Id -- 'c' and 'n'
+dfBindComp :: Type -- element type
-> (LPat GhcTc, CoreExpr)
-> [ExprStmt GhcTc] -- the rest of the qual's
-> DsM CoreExpr
-dfBindComp c_id n_id (pat, core_list1) quals = do
+dfBindComp elt_ty (pat, core_list1) quals = do
-- find the required type
let x_ty = hsLPatType pat
- let b_ty = idType n_id
-- create some new local id's
- b <- newSysLocalDs ManyTy b_ty
x <- newSysLocalDs ManyTy x_ty
-- build rest of the comprehension
- core_rest <- dfListComp c_id b quals
+ core_rest <- dfListComp elt_ty quals
-- build the pattern match
core_expr <- matchSimply (Var x) (StmtCtxt (HsDoStmt ListComp)) ManyTy
- pat core_rest (Var b)
+ pat core_rest (mkListExpr elt_ty [])
-- now build the outermost foldr, and return
- mkFoldrExpr x_ty b_ty (mkLams [x, b] core_expr) (Var n_id) core_list1
+ mkConcatMapExpr x_ty elt_ty (mkLams [x] core_expr) core_list1
{-
************************************************************************
=====================================
libraries/ghc-internal/src/GHC/Internal/Base.hs
=====================================
@@ -346,6 +346,229 @@ infixl 4 <*>, <*, *>, <**>
default () -- Double isn't available yet
+data Stream a = forall s. Stream (s -> Step s a) !s
+data Step s a = Yield a !s | Skip !s | Done
+
+unstream :: Stream a -> [a]
+unstream (Stream next s0) = go s0 where
+ go !s = case next s of
+ Yield x s' -> x : go s'
+ Skip s' -> go s'
+ Done -> []
+{-# INLINE [1] unstream #-}
+
+-- This changes an unstream into a cheapUnstream, which means GHC will be free
+-- to duplicate the list producing stream.
+cheap :: [a] -> [a]
+cheap x = x
+{-# INLINE [1] cheap #-}
+
+{-# RULES "cheap/unstream" forall x. cheap (unstream x) = cheapUnstream x #-}
+
+cheapUnstream :: Stream a -> [a]
+cheapUnstream (Stream next s0) = go s0 where
+ go !s = case next s of
+ Yield x s' -> x : go s'
+ Skip s' -> go s'
+ Done -> []
+{-# INLINE CONLIKE [1] cheapUnstream #-}
+
+data Lazy a = L a
+
+streamNext :: Lazy [a] -> Step (Lazy [a]) a
+streamNext (L []) = Done
+streamNext (L (x:xs)) = Yield x (L xs)
+
+stream :: [a] -> Stream a
+stream = Stream streamNext . L where
+{-# INLINE [1] stream #-}
+
+{-# RULES
+"unstream/stream" forall xs. unstream (stream xs) = xs
+"cheapUnstream/stream" forall xs. cheapUnstream (stream xs) = xs
+"stream/unstream" forall xs. stream (unstream xs) = xs
+"stream/cheapUnstream" forall xs. stream (cheapUnstream xs) = xs
+"stream/build" forall (f :: forall b. (a -> b -> b) -> b -> b).
+ stream (build f) = Stream streamNext (L (f (:) []))
+ #-}
+
+data AppendState s1 s2 = AS1 !s1 | AS2 !s2
+
+appendS :: Stream a -> Stream a -> Stream a
+appendS (Stream next1 s01) (Stream next2 s02) = Stream next' (AS1 s01) where
+ next' (AS1 s1) =
+ case next1 s1 of
+ Yield x s1' -> Yield x (AS1 s1')
+ Skip s1' -> Skip (AS1 s1')
+ Done -> Skip (AS2 s02)
+ next' (AS2 s2) =
+ case next2 s2 of
+ Yield x s2' -> Yield x (AS2 s2')
+ Skip s2' -> Skip (AS2 s2')
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE appendS #-}
+
+append1S :: Stream a -> [a] -> [a]
+append1S (Stream next s0) xs = go s0 where
+ go !s =
+ case next s of
+ Yield x s' -> x : go s'
+ Skip s' -> go s'
+ Done -> xs
+{-# INLINE [0] append1S #-}
+
+(++) :: [a] -> [a] -> [a]
+(++) [] ys = ys
+(++) (x:xs) ys = x : xs ++ ys
+{-# NOINLINE [1] (++) #-}
+
+-- NOTE: This is quite subtle as we do not want to copy the last list in
+--
+-- xs1 ++ xs2 ++ ... ++ xsn
+--
+-- Indeed, we don't really want to fuse the above at all unless at least
+-- one of the arguments has the form (unstream s) or the result of the
+-- concatenation is streamed. The rules below do precisely that. Note they
+-- really fuse instead of just rewriting things into a fusible form so there
+-- is no need to rewrite back.
+
+{-# RULES
+"++ -> fused on 1st arg" [~1] forall xs ys.
+ unstream xs ++ ys = append1S xs ys
+"++ -> fused on 2nd arg" [~1] forall xs ys.
+ append1S xs (unstream ys) = unstream (appendS xs ys)
+"++ -> fused (1)" [~1] forall xs ys.
+ stream (xs ++ ys) = appendS (stream xs) (stream ys)
+"++ -> fused (2)" [~1] forall xs ys.
+ stream (append1S xs ys) = appendS xs (stream ys)
+
+"++ -> 1st arg empty" forall xs.
+ [] ++ xs = xs
+"++ -> 2nd arg empty" forall xs.
+ xs ++ [] = xs
+"++ / :" forall x xs ys.
+ (x:xs) ++ ys = x : (xs ++ ys)
+ #-}
+
+foldrS :: (a -> b -> b) -> b -> Stream a -> b
+foldrS k z (Stream next s0) = go s0 where
+ go !s =
+ case next s of
+ Yield x s' -> k x (go s')
+ Skip s' -> go s'
+ Done -> z
+{-# INLINE foldrS #-}
+
+foldr :: (a -> b -> b) -> b -> [a] -> b
+foldr k z = foldrS k z . stream
+{-# INLINE foldr #-}
+
+mapS :: (a -> b) -> Stream a -> Stream b
+mapS f (Stream next s0) = Stream next' s0 where
+ next' !s =
+ case next s of
+ Yield x s' -> Yield (f x) s'
+ Skip s' -> Skip s'
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE mapS #-}
+
+map :: (a -> b) -> [a] -> [b]
+map f = unstream . mapS f . stream
+{-# INLINE map #-}
+
+data ConcatMapState s a = ConcatMapState1 !s | forall is. ConcatMapState2 !s (is -> Step is a) !is
+
+concatMapS :: (a -> Stream b) -> Stream a -> Stream b
+concatMapS f (Stream next s0) = Stream next' (ConcatMapState1 s0)
+ where
+ {-# INLINE next' #-}
+ next' (ConcatMapState1 s) = case next s of
+ Done -> Done
+ Skip s' -> Skip (ConcatMapState1 s')
+ Yield x s' ->
+ case f x of
+ Stream inext is0 -> Skip (ConcatMapState2 s' inext is0)
+
+ next' (ConcatMapState2 s inext is) = case inext is of
+ Done -> Skip (ConcatMapState1 s)
+ Skip is' -> Skip (ConcatMapState2 s inext is')
+ Yield x is' -> Yield x (ConcatMapState2 s inext is')
+{-# INLINE [0] concatMapS #-}
+
+-- {-# RULES
+-- "concatMapS/singleton" forall f. concatMapS (\x -> stream [f x]) = mapS f
+-- #-}
+
+data ConcatMap'State s1 a s2 = CM'S1 !s1 | CM'S2 !s1 a !s2
+
+concatMapS' :: (a -> s -> Step s b) -> (a -> s) -> Stream a -> Stream b
+concatMapS' next2 f (Stream next1 s0) = Stream next' (CM'S1 s0)
+ where
+ {-# INLINE next' #-}
+ next' (CM'S1 s) = case next1 s of
+ Done -> Done
+ Skip s' -> Skip (CM'S1 s')
+ Yield x s' -> Skip (CM'S2 s' x (f x))
+
+ next' (CM'S2 s a t) = case next2 a t of
+ Done -> Skip (CM'S1 s)
+ Skip t' -> Skip (CM'S2 s a t')
+ Yield x t' -> Yield x (CM'S2 s a t')
+{-# INLINE concatMapS' #-}
+
+-- data ConcatMap''State s1 a s2 = CM''S1 !s1 | CM''S2 !s1 !s2
+--
+-- concatMapS'' :: (s -> Step s b) -> (a -> s) -> Stream a -> Stream b
+-- concatMapS'' next2 f (Stream next1 s0) = Stream next (CM''S1 s0)
+-- where
+-- {-# INLINE next #-}
+-- next (CM''S1 s) = case next1 s of
+-- Done -> Done
+-- Skip s' -> Skip (CM''S1 s')
+-- Yield x s' -> Skip (CM''S2 s' (f x))
+--
+-- next (CM''S2 s t) = case next2 t of
+-- Done -> Skip (CM''S1 s)
+-- Skip t' -> Skip (CM''S2 s t')
+-- Yield x t' -> Yield x (CM''S2 s t')
+-- {-# INLINE concatMapS'' #-}
+
+-- {-# RULES
+-- "concatMap" forall step f. concatMapS (\x -> Stream (step x) (f x)) = concatMapS' step f
+-- #-}
+
+-- Shouldn't be necessary, because stream gets inlined anyway in phase 1
+-- "concatMap/stream" [1] forall f. concatMapS (\x -> stream (f x)) = concatMapS' (\_ -> streamStep) f
+
+-- | Map a function returning a list over a list and concatenate the results.
+-- 'concatMap' can be seen as the composition of 'concat' and 'map'.
+--
+-- > concatMap f xs == (concat . map f) xs
+--
+-- ==== __Examples__
+--
+-- >>> concatMap (\i -> [-i,i]) []
+-- []
+--
+-- >>> concatMap (\i -> [-i, i]) [1, 2, 3]
+-- [-1,1,-2,2,-3,3]
+--
+-- >>> concatMap ('replicate' 3) [0, 2, 4]
+-- [0,0,0,2,2,2,4,4,4]
+concatMap :: (a -> [b]) -> [a] -> [b]
+concatMap f = foldr ((++) . f) []
+
+{-# NOINLINE [1] concatMap #-}
+
+{-# RULES
+"concatMap" forall f . concatMap f = unstream . concatMapS (stream . f) . stream
+-- "concatMap" forall f xs . concatMap f xs =
+-- build (\c n -> foldr (\x b -> foldr c b (f x)) n xs)
+ #-}
+
+
{-
Note [Tracking dependencies on primitives]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -1780,17 +2003,17 @@ The rest of the prelude list functions are in GHC.List.
--
-- > foldr f z [x1, x2, ..., xn] == x1 `f` (x2 `f` ... (xn `f` z)...)
-foldr :: (a -> b -> b) -> b -> [a] -> b
--- foldr _ z [] = z
--- foldr f z (x:xs) = f x (foldr f z xs)
-{-# INLINE [0] foldr #-}
--- Inline only in the final stage, after the foldr/cons rule has had a chance
--- Also note that we inline it when it has *two* parameters, which are the
--- ones we are keen about specialising!
-foldr k z = go
- where
- go [] = z
- go (y:ys) = y `k` go ys
+-- foldr :: (a -> b -> b) -> b -> [a] -> b
+-- -- foldr _ z [] = z
+-- -- foldr f z (x:xs) = f x (foldr f z xs)
+-- {-# INLINE [0] foldr #-}
+-- -- Inline only in the final stage, after the foldr/cons rule has had a chance
+-- -- Also note that we inline it when it has *two* parameters, which are the
+-- -- ones we are keen about specialising!
+-- foldr k z = go
+-- where
+-- go [] = z
+-- go (y:ys) = y `k` go ys
-- | A list producer that can be fused with 'foldr'.
-- This function is merely
@@ -1825,38 +2048,38 @@ augment :: forall a. (forall b. (a->b->b) -> b -> b) -> [a] -> [a]
{-# INLINE [1] augment #-}
augment g xs = g (:) xs
-{-# RULES
-"fold/build" forall k z (g::forall b. (a->b->b) -> b -> b) .
- foldr k z (build g) = g k z
-
-"foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) .
- foldr k z (augment g xs) = g k (foldr k z xs)
-
-"foldr/id" foldr (:) [] = \x -> x
-"foldr/app" [1] forall ys. foldr (:) ys = \xs -> xs ++ ys
- -- Only activate this from phase 1, because that's
- -- when we disable the rule that expands (++) into foldr
-
--- The foldr/cons rule looks nice, but it can give disastrously
--- bloated code when compiling
--- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
--- i.e. when there are very very long literal lists
--- So I've disabled it for now. We could have special cases
--- for short lists, I suppose.
--- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
-
-"foldr/single" forall k z x. foldr k z [x] = k x z
-"foldr/nil" forall k z. foldr k z [] = z
-
-"foldr/cons/build" forall k z x (g::forall b. (a->b->b) -> b -> b) .
- foldr k z (x:build g) = k x (g k z)
-
-"augment/build" forall (g::forall b. (a->b->b) -> b -> b)
- (h::forall b. (a->b->b) -> b -> b) .
- augment g (build h) = build (\c n -> g c (h c n))
-"augment/nil" forall (g::forall b. (a->b->b) -> b -> b) .
- augment g [] = build g
- #-}
+-- {-# RULES
+-- "fold/build" forall k z (g::forall b. (a->b->b) -> b -> b) .
+-- foldr k z (build g) = g k z
+--
+-- "foldr/augment" forall k z xs (g::forall b. (a->b->b) -> b -> b) .
+-- foldr k z (augment g xs) = g k (foldr k z xs)
+--
+-- "foldr/id" foldr (:) [] = \x -> x
+-- "foldr/app" [1] forall ys. foldr (:) ys = \xs -> xs ++ ys
+-- -- Only activate this from phase 1, because that's
+-- -- when we disable the rule that expands (++) into foldr
+--
+-- -- The foldr/cons rule looks nice, but it can give disastrously
+-- -- bloated code when compiling
+-- -- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
+-- -- i.e. when there are very very long literal lists
+-- -- So I've disabled it for now. We could have special cases
+-- -- for short lists, I suppose.
+-- -- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
+--
+-- "foldr/single" forall k z x. foldr k z [x] = k x z
+-- "foldr/nil" forall k z. foldr k z [] = z
+--
+-- "foldr/cons/build" forall k z x (g::forall b. (a->b->b) -> b -> b) .
+-- foldr k z (x:build g) = k x (g k z)
+--
+-- "augment/build" forall (g::forall b. (a->b->b) -> b -> b)
+-- (h::forall b. (a->b->b) -> b -> b) .
+-- augment g (build h) = build (\c n -> g c (h c n))
+-- "augment/nil" forall (g::forall b. (a->b->b) -> b -> b) .
+-- augment g [] = build g
+-- #-}
-- This rule is true, but not (I think) useful:
-- augment g (augment h t) = augment (\cn -> g c (h c n)) t
@@ -1883,13 +2106,13 @@ augment g xs = g (:) xs
--
-- >>> map (\n -> 3 * n + 1) [1, 2, 3]
-- [4,7,10]
-map :: (a -> b) -> [a] -> [b]
-{-# NOINLINE [0] map #-}
- -- We want the RULEs "map" and "map/coerce" to fire first.
- -- map is recursive, so won't inline anyway,
- -- but saying so is more explicit, and silences warnings
-map _ [] = []
-map f (x:xs) = f x : map f xs
+-- map :: (a -> b) -> [a] -> [b]
+-- {-# NOINLINE [0] map #-}
+-- -- We want the RULEs "map" and "map/coerce" to fire first.
+-- -- map is recursive, so won't inline anyway,
+-- -- but saying so is more explicit, and silences warnings
+-- map _ [] = []
+-- map f (x:xs) = f x : map f xs
-- Note eta expanded
mapFB :: (elt -> lst -> lst) -> (a -> elt) -> a -> lst -> lst
@@ -1931,12 +2154,12 @@ The rules for map work like this.
* Any similarity to the Functor laws for [] is expected.
-}
-{-# RULES
-"map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs)
-"mapList" [1] forall f. foldr (mapFB (:) f) [] = map f
-"mapFB" forall c f g. mapFB (mapFB c f) g = mapFB c (f.g)
-"mapFB/id" forall c. mapFB c (\x -> x) = c
- #-}
+-- {-# RULES
+-- "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs)
+-- "mapList" [1] forall f. foldr (mapFB (:) f) [] = map f
+-- "mapFB" forall c f g. mapFB (mapFB c f) g = mapFB c (f.g)
+-- "mapFB/id" forall c. mapFB c (\x -> x) = c
+-- #-}
-- See Breitner, Eisenberg, Peyton Jones, and Weirich, "Safe Zero-cost
-- Coercions for Haskell", section 6.5:
@@ -1976,21 +2199,21 @@ The rules for map work like this.
--
-- >>> [3, 2, 1] ++ []
-- [3,2,1]
-(++) :: [a] -> [a] -> [a]
-{-# NOINLINE [2] (++) #-}
- -- Give time for the RULEs for (++) to fire in InitialPhase
- -- It's recursive, so won't inline anyway,
- -- but saying so is more explicit
-(++) [] ys = ys
-(++) (x:xs) ys = x : xs ++ ys
+-- (++) :: [a] -> [a] -> [a]
+-- {-# NOINLINE [2] (++) #-}
+-- -- Give time for the RULEs for (++) to fire in InitialPhase
+-- -- It's recursive, so won't inline anyway,
+-- -- but saying so is more explicit
+-- (++) [] ys = ys
+-- (++) (x:xs) ys = x : xs ++ ys
-{-# RULES
-"++/literal" forall x. (++) (unpackCString# x) = unpackAppendCString# x
-"++/literal_utf8" forall x. (++) (unpackCStringUtf8# x) = unpackAppendCStringUtf8# x #-}
-
-{-# RULES
-"++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
- #-}
+-- {-# RULES
+-- "++/literal" forall x. (++) (unpackCString# x) = unpackAppendCString# x
+-- "++/literal_utf8" forall x. (++) (unpackCStringUtf8# x) = unpackAppendCStringUtf8# x #-}
+--
+-- {-# RULES
+-- "++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys
+-- #-}
-- |'otherwise' is defined as the value 'True'. It helps to make
@@ -2512,20 +2735,20 @@ iShiftRL# :: Int# -> Int# -> Int#
a `iShiftRL#` b = (a `uncheckedIShiftRL#` b) `andI#` shift_mask WORD_SIZE_IN_BITS# b
-- Rules for C strings (the functions themselves are now in GHC.CString)
-{-# RULES
-"unpack" [~1] forall a . unpackCString# a = build (unpackFoldrCString# a)
-"unpack-list" [1] forall a . unpackFoldrCString# a (:) [] = unpackCString# a
-"unpack-append" forall a n . unpackFoldrCString# a (:) n = unpackAppendCString# a n
-"unpack-append-nil" forall a . unpackAppendCString# a [] = unpackCString# a
-
-"unpack-utf8" [~1] forall a . unpackCStringUtf8# a = build (unpackFoldrCStringUtf8# a)
-"unpack-list-utf8" [1] forall a . unpackFoldrCStringUtf8# a (:) [] = unpackCStringUtf8# a
-"unpack-append-utf8" forall a n . unpackFoldrCStringUtf8# a (:) n = unpackAppendCStringUtf8# a n
-"unpack-append-nil-utf8" forall a . unpackAppendCStringUtf8# a [] = unpackCStringUtf8# a
-
--- There's a built-in rule (in GHC.Core.Op.ConstantFold) for
--- unpackFoldr "foo" c (unpackFoldr "baz" c n) = unpackFoldr "foobaz" c n
-
--- See also the Note [String literals in GHC] in CString.hs
-
- #-}
+-- {-# RULES
+-- "unpack" [~1] forall a . unpackCString# a = build (unpackFoldrCString# a)
+-- "unpack-list" [1] forall a . unpackFoldrCString# a (:) [] = unpackCString# a
+-- "unpack-append" forall a n . unpackFoldrCString# a (:) n = unpackAppendCString# a n
+-- "unpack-append-nil" forall a . unpackAppendCString# a [] = unpackCString# a
+--
+-- "unpack-utf8" [~1] forall a . unpackCStringUtf8# a = build (unpackFoldrCStringUtf8# a)
+-- "unpack-list-utf8" [1] forall a . unpackFoldrCStringUtf8# a (:) [] = unpackCStringUtf8# a
+-- "unpack-append-utf8" forall a n . unpackFoldrCStringUtf8# a (:) n = unpackAppendCStringUtf8# a n
+-- "unpack-append-nil-utf8" forall a . unpackAppendCStringUtf8# a [] = unpackCStringUtf8# a
+--
+-- -- There's a built-in rule (in GHC.Core.Op.ConstantFold) for
+-- -- unpackFoldr "foo" c (unpackFoldr "baz" c n) = unpackFoldr "foobaz" c n
+--
+-- -- See also the Note [String literals in GHC] in CString.hs
+--
+-- #-}
=====================================
libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs
=====================================
@@ -64,7 +64,7 @@ import GHC.Internal.Arr ( Array(..), elems, numElements,
foldlElems, foldrElems,
foldlElems', foldrElems',
foldl1Elems, foldr1Elems)
-import GHC.Internal.Base hiding ( foldr )
+import GHC.Internal.Base hiding ( foldr , concatMap )
import GHC.Internal.Generics
import GHC.Tuple (Solo (..))
import GHC.Internal.Num ( Num(..) )
=====================================
libraries/ghc-internal/src/GHC/Internal/Enum.hs
=====================================
@@ -32,6 +32,7 @@ module GHC.Internal.Enum(
) where
import GHC.Internal.Base hiding ( many )
+import GHC.Internal.List (eftInt)
import GHC.Internal.Char
import GHC.Num.Integer
import GHC.Internal.Num
@@ -610,15 +611,15 @@ instance Enum Int where
* Phase 0: optionally inline eftInt
-}
-{-# NOINLINE [1] eftInt #-}
-eftInt :: Int# -> Int# -> [Int]
--- [x1..x2]
-eftInt x0 y | isTrue# (x0 ># y) = []
- | otherwise = go x0
- where
- go x = I# x : if isTrue# (x ==# y)
- then []
- else go (x +# 1#)
+-- {-# NOINLINE [1] eftInt #-}
+-- eftInt :: Int# -> Int# -> [Int]
+-- -- [x1..x2]
+-- eftInt x0 y | isTrue# (x0 ># y) = []
+-- | otherwise = go x0
+-- where
+-- go x = I# x : if isTrue# (x ==# y)
+-- then []
+-- else go (x +# 1#)
{-# INLINE [0] eftIntFB #-} -- See Note [Inline FB functions] in GHC.Internal.List
eftIntFB :: (Int -> r -> r) -> r -> Int# -> Int# -> r
=====================================
libraries/ghc-internal/src/GHC/Internal/IO/Handle/FD.hs
=====================================
@@ -25,7 +25,7 @@ module GHC.Internal.IO.Handle.FD (
mkHandleFromFD, fdToHandle, fdToHandle', handleToFd
) where
-import GHC.Internal.Base
+import GHC.Internal.Base hiding (Stream)
import GHC.Internal.Show
import GHC.Internal.Control.Exception (try)
import GHC.Internal.Data.Maybe
=====================================
libraries/ghc-internal/src/GHC/Internal/List.hs
=====================================
@@ -1,6 +1,6 @@
{-# LANGUAGE Trustworthy #-}
-{-# LANGUAGE CPP, NoImplicitPrelude, ScopedTypeVariables #-}
-{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE CPP, NoImplicitPrelude, ScopedTypeVariables, ExistentialQuantification #-}
+{-# LANGUAGE BangPatterns, MagicHash #-}
{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
-----------------------------------------------------------------------------
@@ -41,6 +41,9 @@ module GHC.Internal.List (
-- * GHC List fusion
augment, build,
+ -- * Enumeration
+ eftInt,
+
) where
import GHC.Internal.Data.Maybe
@@ -52,6 +55,927 @@ import GHC.Internal.Stack.Types (HasCallStack)
infixl 9 !?, !!
infix 4 `elem`, `notElem`
+data Tuple a b = !a :!: !b
+data Option a = None | Some !a
+
+eftIntS :: Int# -> Int# -> Stream Int
+eftIntS x y = Stream next (I# x) where
+ next !s
+ | s <= I# y = Yield s (s + 1)
+ | otherwise = Done
+ {-# INLINE next #-}
+{-# INLINE eftIntS #-}
+
+eftInt :: Int# -> Int# -> [Int]
+eftInt = \x y -> cheapUnstream (eftIntS x y)
+{-# INLINE eftInt #-}
+
+-- unfoldrS :: (a -> Maybe (a, b)) -> a -> Stream b
+-- unfoldrS f x0 = Stream next x0 where
+-- next s =
+-- case f s of
+-- Just (s', x) -> Yield x s'
+-- Nothing -> Done
+-- {-# INLINE next #-}
+-- {-# INLINE unfoldrS #-}
+
+data ZipState s1 a s2
+ = ZipState1 !s1 !s2
+ | ZipState2 !s1 a !s2
+
+zipS :: Stream a -> Stream b -> Stream (a, b)
+zipS (Stream next1 s01) (Stream next2 s02) = Stream next' (ZipState1 s01 s02) where
+ next' (ZipState1 s1 s2) =
+ case next1 s1 of
+ Yield x s1' ->
+ case next2 s2 of
+ Yield y s2' ->
+ Yield (x, y) (ZipState1 s1' s2')
+ Skip s2' -> Skip (ZipState2 s1' x s2')
+ Done -> Done
+ Skip s1' -> Skip (ZipState1 s1' s2)
+ Done -> Done
+ next' (ZipState2 s1' x s2) =
+ case next2 s2 of
+ Yield y s2' -> Yield (x, y) (ZipState1 s1' s2')
+ Skip s2' -> Skip (ZipState2 s1' x s2')
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE zipS #-}
+
+data Zip3State s1 a s2 b s3
+ = Zip3State1 !s1 !s2 !s3
+ | Zip3State2 !s1 a !s2 !s3
+ | Zip3State3 !s1 a !s2 b !s3
+
+zip3S :: Stream a -> Stream b -> Stream c -> Stream (a, b, c)
+zip3S (Stream next1 s01) (Stream next2 s02) (Stream next3 s03) = Stream next' (Zip3State1 s01 s02 s03) where
+ next' (Zip3State1 s1 s2 s3) =
+ case next1 s1 of
+ Yield x s1' ->
+ case next2 s2 of
+ Yield y s2' ->
+ case next3 s3 of
+ Yield z s3' -> Yield (x, y, z) (Zip3State1 s1' s2' s3')
+ Skip s3' -> Skip (Zip3State3 s1' x s2' y s3')
+ Done -> Done
+ Skip s2' -> Skip (Zip3State2 s1' x s2' s3)
+ Done -> Done
+ Skip s1' -> Skip (Zip3State1 s1' s2 s3)
+ Done -> Done
+ next' (Zip3State2 s1' x s2 s3) =
+ case next2 s2 of
+ Yield y s2' ->
+ case next3 s3 of
+ Yield z s3' -> Yield (x,y,z) (Zip3State1 s1' s2' s3')
+ Skip s3' -> Skip (Zip3State3 s1' x s2' y s3')
+ Done -> Done
+ Skip s2' -> Skip (Zip3State2 s1' x s2' s3)
+ Done -> Done
+ next' (Zip3State3 s1' x s2' y s3) =
+ case next3 s3 of
+ Yield z s3' -> Yield (x,y,z) (Zip3State1 s1' s2' s3')
+ Skip s3' -> Skip (Zip3State3 s1' x s2' y s3')
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE zip3S #-}
+
+zipWithS :: (a -> b -> c) -> Stream a -> Stream b -> Stream c
+zipWithS f (Stream next1 s01) (Stream next2 s02) = Stream next' (ZipState1 s01 s02) where
+ next' (ZipState1 s1 s2) =
+ case next1 s1 of
+ Yield x s1' ->
+ case next2 s2 of
+ Yield y s2' ->
+ Yield (f x y) (ZipState1 s1' s2')
+ Skip s2' -> Skip (ZipState2 s1' x s2')
+ Done -> Done
+ Skip s1' -> Skip (ZipState1 s1' s2)
+ Done -> Done
+ next' (ZipState2 s1' x s2) =
+ case next2 s2 of
+ Yield y s2' -> Yield (f x y) (ZipState1 s1' s2')
+ Skip s2' -> Skip (ZipState2 s1' x s2')
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE zipWithS #-}
+
+zipWith3S :: (a -> b -> c -> d) -> Stream a -> Stream b -> Stream c -> Stream d
+zipWith3S f (Stream next1 s01) (Stream next2 s02) (Stream next3 s03) = Stream next' (Zip3State1 s01 s02 s03) where
+ next' (Zip3State1 s1 s2 s3) =
+ case next1 s1 of
+ Yield x s1' ->
+ case next2 s2 of
+ Yield y s2' ->
+ case next3 s3 of
+ Yield z s3' -> Yield (f x y z) (Zip3State1 s1' s2' s3')
+ Skip s3' -> Skip (Zip3State3 s1' x s2' y s3')
+ Done -> Done
+ Skip s2' -> Skip (Zip3State2 s1' x s2' s3)
+ Done -> Done
+ Skip s1' -> Skip (Zip3State1 s1' s2 s3)
+ Done -> Done
+ next' (Zip3State2 s1' x s2 s3) =
+ case next2 s2 of
+ Yield y s2' ->
+ case next3 s3 of
+ Yield z s3' -> Yield (f x y z) (Zip3State1 s1' s2' s3')
+ Skip s3' -> Skip (Zip3State3 s1' x s2' y s3')
+ Done -> Done
+ Skip s2' -> Skip (Zip3State2 s1' x s2' s3)
+ Done -> Done
+ next' (Zip3State3 s1' x s2' y s3) =
+ case next3 s3 of
+ Yield z s3' -> Yield (f x y z) (Zip3State1 s1' s2' s3')
+ Skip s3' -> Skip (Zip3State3 s1' x s2' y s3')
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE zipWith3S #-}
+
+-- unzipS :: Stream (a, b) -> (Stream a, Stream b)
+-- unzipS s = (mapS fst s, mapS snd s)
+-- {-# INLINE unzipS #-}
+
+unzipS :: Stream (a, b) -> ([a], [b])
+unzipS (Stream next s0) = go s0 where
+ go s =
+ case next s of
+ Yield (x, y) s' -> let (xs, ys) = go s' in (x:xs, y:ys)
+ Skip s' -> go s'
+ Done -> ([], [])
+{-# INLINE unzipS #-}
+
+-- unzip3S :: Stream (a, b, c) -> (Stream a, Stream b, Stream c)
+-- unzip3S s = (mapS (\(x,_,_) -> x) s, mapS (\(_,x,_) -> x) s, mapS (\(_,_,x) -> x) s)
+-- {-# INLINE unzip3S #-}
+
+unzip3S :: Stream (a, b, c) -> ([a], [b], [c])
+unzip3S (Stream next s0) = go s0 where
+ go !s =
+ case next s of
+ Yield (x, y, z) s' -> let (xs, ys, zs) = go s' in (x:xs, y:ys, z:zs)
+ Skip s' -> go s'
+ Done -> ([], [], [])
+{-# INLINE unzip3S #-}
+
+foldrS' :: (a -> b -> b) -> b -> Stream a -> b
+foldrS' k z (Stream next s0) = go s0 where
+ go !s =
+ case next s of
+ Yield x s' -> k x $! go s'
+ Skip s' -> go s'
+ Done -> z
+{-# INLINE foldrS' #-}
+
+foldr1S :: (a -> a -> a) -> Stream a -> a
+foldr1S f (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s' -> go2 x s'
+ Skip s' -> go1 s'
+ Done -> errorEmptyList "foldr1"
+ go2 x !s =
+ case next s of
+ Yield y s' -> f x (go2 y s')
+ Skip s' -> go2 x s'
+ Done -> x
+{-# INLINE foldr1S #-}
+
+nullS :: Stream a -> Bool
+nullS (Stream next s0) = go s0 where
+ go !s =
+ case next s of
+ Yield{} -> False
+ Skip s' -> go s'
+ Done -> True
+{-# INLINE nullS #-}
+
+lengthS :: Stream a -> Int
+lengthS (Stream next s0) = go 0 s0 where
+ go !n !s =
+ case next s of
+ Yield _ s' -> go (n + 1) s'
+ Skip s' -> go n s'
+ Done -> n
+{-# INLINE lengthS #-}
+
+elemS :: Eq a => a -> Stream a -> Bool
+elemS x0 (Stream next s0) = go s0 where
+ go s =
+ case next s of
+ Yield x s' -> x == x0 || go s'
+ Skip s' -> go s'
+ Done -> False
+{-# INLINE elemS #-}
+
+notElemS :: Eq a => a -> Stream a -> Bool
+notElemS x0 (Stream next s0) = go s0 where
+ go s =
+ case next s of
+ Yield x s' -> x /= x0 && go s'
+ Skip s' -> go s'
+ Done -> True
+{-# INLINE notElemS #-}
+
+maximumS :: Ord a => Stream a -> a
+maximumS (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s' -> go2 x s'
+ Skip s' -> go1 s'
+ Done -> errorEmptyList "maximum"
+ go2 x !s =
+ case next s of
+ Yield y s'
+ | y > x -> go2 y s'
+ | otherwise -> go2 x s'
+ Skip s' -> go2 x s'
+ Done -> x
+{-# INLINE maximumS #-}
+
+minimumS :: Ord a => Stream a -> a
+minimumS (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s' -> go2 x s'
+ Skip s' -> go1 s'
+ Done -> errorEmptyList "minimum"
+ go2 x !s =
+ case next s of
+ Yield y s'
+ | y < x -> go2 y s'
+ | otherwise -> go2 x s'
+ Skip s' -> go2 x s'
+ Done -> x
+{-# INLINE minimumS #-}
+
+takeS :: Int -> Stream a -> Stream a
+takeS n (Stream next s0) = Stream next' (s0 :!: n) where
+ next' (_ :!: 0) = Done
+ next' (s :!: i) =
+ case next s of
+ Yield x s' -> Yield x (s' :!: (i - 1))
+ Skip s' -> Skip (s' :!: i)
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE takeS #-}
+
+-- dropS :: Int -> Stream a -> Stream a
+-- dropS n (Stream next s0) = Stream next (f n s0) where
+-- f i s
+-- | i <= 0 = s
+-- | otherwise =
+-- case next s of
+-- Yield _ s' -> f (i - 1) s'
+-- Skip s' -> f i s'
+-- Done -> s
+-- {-# INLINE dropS #-}
+
+dropS :: Int -> Stream a -> Stream a
+dropS n (Stream next s0) = Stream next' (n :!: s0) where
+ next' (i :!: s)
+ | i > 0 =
+ case next s of
+ Yield _ s' -> Skip ((i - 1) :!: s')
+ Skip s' -> Skip (i :!: s')
+ Done -> Done
+ | otherwise =
+ case next s of
+ Yield x s' -> Yield x (i :!: s')
+ Skip s' -> Skip (i :!: s')
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE dropS #-}
+
+cheapSplitAtS :: Int -> Stream a -> ([a], [a])
+cheapSplitAtS n s = (cheapUnstream (takeS n s), cheapUnstream (dropS n s))
+{-# INLINE cheapSplitAtS #-}
+
+splitAtS :: Int -> Stream a -> ([a], [a])
+splitAtS n (Stream next s0) = go1 n s0 where
+ go1 !i !s
+ | i > 0 =
+ case next s of
+ Yield x s' -> let (xs,ys) = go1 (i - 1) s' in (x : xs, ys)
+ Skip s' -> go1 i s'
+ Done -> ([], [])
+ | otherwise = ([], go2 s)
+ go2 !s =
+ case next s of
+ Yield x s' -> x : go2 s'
+ Skip s' -> go2 s'
+ Done -> []
+{-# INLINE splitAtS #-}
+
+takeWhileS :: (a -> Bool) -> Stream a -> Stream a
+takeWhileS p (Stream next s0) = Stream next' s0 where
+ next' !s =
+ case next s of
+ Yield x s'
+ | p x -> Yield x s'
+ | otherwise -> Done
+ Skip s' -> Skip s'
+ Done -> Done
+{-# INLINE takeWhileS #-}
+
+dropWhileS :: (a -> Bool) -> Stream a -> Stream a
+dropWhileS p (Stream next s0) = Stream next' (True :!: s0) where
+ next' (True :!: s) =
+ case next s of
+ Yield x s'
+ | p x -> Skip (True :!: s')
+ | otherwise -> Yield x (False :!: s')
+ Skip s' -> Skip (True :!: s')
+ Done -> Done
+ next' (False :!: s) =
+ case next s of
+ Yield x s' -> Yield x (False :!: s')
+ Skip s' -> Skip (False :!: s')
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE dropWhileS #-}
+
+-- nubS :: Eq a => Stream a -> Stream a
+-- nubS (Stream next s0) = Stream next' ([] :!: s0) where
+-- next' (xs :!: s) =
+-- case next s of
+-- Yield x s'
+-- | x `elem` xs -> Skip (xs :!: s')
+-- | otherwise -> Yield x ((x : xs) :!: s')
+-- Skip s' -> Skip (xs :!: s')
+-- Done -> Done
+-- {-# INLINE next' #-}
+-- {-# INLINE nubS #-}
+
+-- spanS :: (a -> Bool) -> Stream a -> (Stream a, Stream a)
+-- spanS f s = (takeWhileS f s, dropWhileS f s)
+-- {-# INLINE spanS #-}
+
+spanS :: (a -> Bool) -> Stream a -> ([a], [a])
+spanS p (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s'
+ | p x -> let (xs, ys) = go1 s' in (x : xs, ys)
+ | otherwise -> ([], x : go2 s')
+ Skip s' -> go1 s'
+ Done -> ([],[])
+ go2 !s =
+ case next s of
+ Yield x s' -> x : go2 s'
+ Skip s' -> go2 s'
+ Done -> []
+{-# INLINE spanS #-}
+
+breakS :: (a -> Bool) -> Stream a -> ([a], [a])
+breakS f = spanS (not . f)
+{-# INLINE breakS #-}
+
+reverseS :: Stream a -> [a]
+reverseS = foldlS' (flip (:)) []
+{-# INLINE reverseS #-}
+
+foldlS :: (b -> a -> b) -> b -> Stream a -> b
+foldlS k z (Stream next s0) = go z s0 where
+ go acc !s =
+ case next s of
+ Yield x s' -> go (k acc x) s'
+ Skip s' -> go acc s'
+ Done -> acc
+{-# INLINE foldlS #-}
+
+foldlS' :: (b -> a -> b) -> b -> Stream a -> b
+foldlS' k z (Stream next s0) = go z s0 where
+ go !acc !s =
+ case next s of
+ Yield x s' -> go (k acc x) s'
+ Skip s' -> go acc s'
+ Done -> acc
+{-# INLINE foldlS' #-}
+
+foldl1S :: (a -> a -> a) -> Stream a -> a
+foldl1S f (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s' -> go2 x s'
+ Skip s' -> go1 s'
+ Done -> errorEmptyList "foldl1"
+ go2 acc !s =
+ case next s of
+ Yield x s' -> go2 (f acc x) s'
+ Skip s' -> go2 acc s'
+ Done -> acc
+{-# INLINE foldl1S #-}
+
+-- consumer
+sumS :: Num a => Stream a -> a
+sumS (Stream next s0) = go 0 s0 where
+ go !acc !s = case next s of
+ Done -> acc
+ Skip s' -> go acc s'
+ Yield x s' -> go (acc + x) s'
+{-# INLINE sumS #-}
+
+productS :: Num a => Stream a -> a
+productS (Stream next s0) = go 1 s0 where
+ go !acc !s = case next s of
+ Done -> acc
+ Skip s' -> go acc s'
+ Yield x s' -> go (acc * x) s'
+{-# INLINE productS #-}
+
+andS :: Stream Bool -> Bool
+andS (Stream next s0) = go True s0 where
+ go !acc !s = case next s of
+ Done -> acc
+ Skip s' -> go acc s'
+ Yield x s' -> go (acc && x) s'
+{-# INLINE andS #-}
+
+orS :: Stream Bool -> Bool
+orS (Stream next s0) = go False s0 where
+ go !acc !s = case next s of
+ Done -> acc
+ Skip s' -> go acc s'
+ Yield x s' -> go (acc || x) s'
+{-# INLINE orS #-}
+
+anyS :: (a -> Bool) -> Stream a -> Bool
+anyS p (Stream next s0) = go False s0 where
+ go !acc !s = case next s of
+ Done -> acc
+ Skip s' -> go acc s'
+ Yield x s' -> go (acc || p x) s'
+{-# INLINE anyS #-}
+
+allS :: (a -> Bool) -> Stream a -> Bool
+allS f (Stream next s0) = go True s0 where
+ go !acc !s = case next s of
+ Done -> acc
+ Skip s' -> go acc s'
+ Yield x s' -> go (acc && f x) s'
+{-# INLINE allS #-}
+
+foldl1S' :: (a -> a -> a) -> Stream a -> a
+foldl1S' f (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s' -> go2 x s'
+ Skip s' -> go1 s'
+ Done -> errorEmptyList "foldl1"
+ go2 !acc !s =
+ case next s of
+ Yield x s' -> go2 (f acc x) s'
+ Skip s' -> go2 acc s'
+ Done -> acc
+{-# INLINE foldl1S' #-}
+
+filterS :: (a -> Bool) -> Stream a -> Stream a
+filterS p (Stream next s0) = Stream next' s0 where
+ next' !s =
+ case next s of
+ Yield x s'
+ | p x -> Yield x s'
+ | otherwise -> Skip s'
+ Skip s' -> Skip s'
+ Done -> Done
+ {-# INLINE next' #-}
+{-# INLINE filterS #-}
+
+lookupS :: Eq a => a -> Stream (a, b) -> Maybe b
+lookupS x0 (Stream next s0) = go s0 where
+ go !s =
+ case next s of
+ Yield (x,y) s'
+ | x0 == x -> Just y
+ | otherwise -> go s'
+ Skip s' -> go s'
+ Done -> Nothing
+{-# INLINE lookupS #-}
+
+-- findS :: (a -> Bool) -> Stream a -> Maybe a
+-- findS p (Stream next s0) = go s0 where
+-- go !s =
+-- case next s of
+-- Yield x s'
+-- | p x -> Just x
+-- | otherwise -> go s'
+-- Skip s' -> go s'
+-- Done -> Nothing
+-- {-# INLINE findS #-}
+--
+-- findIndexS :: (a -> Bool) -> Stream a -> Maybe Int
+-- findIndexS p (Stream next s0) = go 0 s0 where
+-- go !i !s =
+-- case next s of
+-- Yield x s'
+-- | p x -> Just i
+-- | otherwise -> go (i + 1) s'
+-- Skip s' -> go i s'
+-- Done -> Nothing
+-- {-# INLINE findIndexS #-}
+
+headS :: Stream a -> a
+headS (Stream next s0) = go s0 where
+ go !s =
+ case next s of
+ Yield x _ -> x
+ Skip s' -> go s'
+ Done -> errorEmptyList "head"
+{-# INLINE headS #-}
+
+lastS :: Stream a -> a
+lastS (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s' -> go2 x s'
+ Skip s' -> go1 s'
+ Done -> errorEmptyList "last"
+ go2 x !s =
+ case next s of
+ Yield x' s' -> go2 x' s'
+ Skip s' -> go2 x s'
+ Done -> x
+{-# INLINE lastS #-}
+
+-- tailS :: Stream a -> Stream a
+-- tailS (Stream next s0) = Stream next (tailF s0) where
+-- tailF !s =
+-- case next s of
+-- Yield _ s' -> s'
+-- Skip s' -> tailF s'
+-- Done -> errorEmptyList "tail"
+--
+-- initS1 :: Stream a -> Stream a
+-- initS1 (Stream next s0) = Stream next' (f s0) where
+-- f !s =
+-- case next s of
+-- Yield x s' -> x :!: s'
+-- Skip s' -> f s'
+-- Done -> errorEmptyList "init"
+-- next' (x :!: s) =
+-- case next s of
+-- Yield y s' -> Yield x (y :!: s')
+-- Skip s' -> Skip (x :!: s')
+-- Done -> Done
+-- {-# INLINE initS1 #-}
+
+initS :: Stream a -> Stream a
+initS (Stream next s0) = Stream next' (Nothing :!: s0) where
+ next' (Nothing :!: s) =
+ case next s of
+ Yield x s' -> Skip (Just x :!: s')
+ Skip s' -> Skip (Nothing :!: s')
+ Done -> errorEmptyList "init"
+ next' (Just x :!: s) =
+ case next s of
+ Yield y s' -> Yield x (Just y :!: s')
+ Skip s' -> Skip (Just x :!: s')
+ Done -> Done
+{-# INLINE initS #-}
+
+unconsS :: Stream a -> Maybe (a, [a])
+unconsS (Stream next s0) = go1 s0 where
+ go1 !s =
+ case next s of
+ Yield x s' -> Just (x, go2 s')
+ Skip s' -> go1 s'
+ Done -> Nothing
+ go2 !s =
+ case next s of
+ Yield x s' -> x : go2 s'
+ Skip s' -> go2 s'
+ Done -> []
+{-# INLINE unconsS #-}
+
+unsnocS :: Stream a -> Maybe ([a], a)
+-- duplicates work:
+-- unsnocS s = if nullS s then Nothing else Just (unstream (initS s), lastS s)
+unsnocS = foldrS (\x xs -> case xs of Nothing -> Just ([], x); Just (ys,y) -> Just (x:ys,y)) Nothing
+{-# INLINE unsnocS #-}
+
+indexHelperS :: Stream a -> Int -> Maybe a
+indexHelperS (Stream next s0) i0 = go i0 s0
+ where
+ go 0 !s =
+ case next s of
+ Yield x _ -> Just x
+ Skip s' -> go 0 s'
+ Done -> Nothing
+ go !i !s =
+ case next s of
+ Yield _ s' -> go (i - 1) s'
+ Skip s' -> go i s'
+ Done -> Nothing
+{-# INLINE indexHelperS #-}
+
+unsafeIndexHelperS :: Stream a -> Int -> a
+unsafeIndexHelperS (Stream next s0) i0 = go i0 s0
+ where
+ go !i !s =
+ case next s of
+ Yield x s' -> if i == 0 then x else go (i - 1) s'
+ Skip s' -> go i s'
+ Done -> tooLarge i
+{-# INLINE unsafeIndexHelperS #-}
+
+scanlS :: (b -> a -> b) -> b -> Stream a -> Stream b
+scanlS k z (Stream next s0) = Stream next' (Just z :!: s0) where
+ next' (Just x :!: s) =
+ case next s of
+ Yield y s' -> Yield x (Just (k x y) :!: s')
+ Skip s' -> Skip (Just x :!: s')
+ Done -> Yield x (Nothing :!: s)
+ next' (Nothing :!: _) = Done
+ {-# INLINE next' #-}
+{-# INLINE scanlS #-}
+
+data Scanl1State a s = Scanl1State1 !s | Scanl1State2 a !s | Scanl1State3
+
+scanl1S :: (a -> a -> a) -> Stream a -> Stream a
+scanl1S k (Stream next s0) = Stream next' (Scanl1State1 s0) where
+ next' (Scanl1State1 s) =
+ case next s of
+ Yield x s' -> Skip (Scanl1State2 x s')
+ Skip s' -> Skip (Scanl1State1 s')
+ Done -> errorEmptyList "scanl1"
+ next' (Scanl1State2 x s) =
+ case next s of
+ Yield y s' -> Yield x (Scanl1State2 (k x y) s')
+ Skip s' -> Skip (Scanl1State2 x s')
+ Done -> Yield x Scanl1State3
+ next' Scanl1State3 = Done
+ {-# INLINE next' #-}
+{-# INLINE scanl1S #-}
+
+scanlS' :: (b -> a -> b) -> b -> Stream a -> Stream b
+scanlS' k z (Stream next s0) = Stream next' (Some (z :!: s0)) where
+ next' (Some (x :!: s)) =
+ case next s of
+ Yield y s' -> Yield x (Some (k x y :!: s'))
+ Skip s' -> Skip (Some (x :!: s'))
+ Done -> Yield x None
+ next' None = Done
+ {-# INLINE next' #-}
+{-# INLINE scanlS' #-}
+
+iterateS :: (a -> a) -> a -> Stream a
+iterateS f = Stream next . L where
+ next (L s) = Yield s (L (f s))
+ {-# INLINE next #-}
+{-# INLINE iterateS #-}
+
+iterateS' :: (a -> a) -> a -> Stream a
+iterateS' f = Stream next where
+ next s = Yield s (f s)
+ {-# INLINE next #-}
+{-# INLINE iterateS' #-}
+
+-- repeatS :: a -> Stream a
+-- repeatS = Stream next . L where
+-- next (L s) = Yield s (L s)
+-- {-# INLINE next #-}
+-- {-# INLINE repeatS #-}
+
+replicateS :: Int -> a -> Stream a
+replicateS n x = Stream next n where
+ next s | s <= 0 = Done
+ | otherwise = Yield x (s - 1)
+ {-# INLINE next #-}
+{-# INLINE replicateS #-}
+
+-- cycleS :: Stream a -> Stream a
+-- cycleS (Stream next s0) = Stream next' s0 where
+-- next' !s =
+-- case next s of
+-- Yield x s' -> Yield x s'
+-- Skip s' -> Skip s'
+-- Done -> Skip s0
+-- {-# INLINE cycleS #-}
+
+concatS :: Stream [a] -> Stream a
+concatS (Stream next s0) = Stream next' (s0 :!: L []) where
+ next' (s :!: L []) =
+ case next s of
+ Yield [] s' -> Skip (s' :!: L [])
+ Yield (x:xs) s' -> Yield x (s' :!: L xs)
+ Skip s' -> Skip (s' :!: L [])
+ Done -> Done
+ next' (s :!: L (x:xs)) = Yield x (s :!: L xs)
+{-# INLINE concatS #-}
+
+scanrS :: (a -> b -> b) -> b -> Stream a -> [b]
+scanrS f q0 = foldrS (\x qs@(q:_) -> f x q : qs) [q0]
+{-# INLINE scanrS #-}
+scanr1S :: (a -> a -> a) -> Stream a -> [a]
+scanr1S f = foldrS (\x qs -> case qs of [] -> [x]; (q:_) -> f x q : qs) []
+{-# INLINE scanr1S #-}
+
+
+-- foldr' :: (a -> b -> b) -> b -> [a] -> b
+-- foldr' k z = foldrS' k z . stream
+-- {-# INLINE foldr' #-}
+-- foldr1 :: (a -> a -> a) -> [a] -> a
+-- foldr1 k = foldr1S k . stream
+-- {-# INLINE foldr1 #-}
+--
+-- foldl :: (b -> a -> b) -> b -> [a] -> b
+-- foldl k z = foldlS k z . stream
+-- {-# INLINE foldl #-}
+-- foldl' :: (b -> a -> b) -> b -> [a] -> b
+-- foldl' k z = foldlS' k z . stream
+-- {-# INLINE foldl' #-}
+-- foldl1 :: (a -> a -> a) -> [a] -> a
+-- foldl1 k = foldl1S k . stream
+-- {-# INLINE foldl1 #-}
+--
+-- null :: [a] -> Bool
+-- null = nullS . stream
+-- {-# INLINE null #-}
+-- length :: [a] -> Int
+-- length = lengthS . stream
+-- {-# INLINE length #-}
+-- elem :: Eq a => a -> [a] -> Bool
+-- elem x = elemS x . stream
+-- {-# INLINE elem #-}
+-- notElem :: Eq a => a -> [a] -> Bool
+-- notElem x = notElemS x . stream
+-- {-# INLINE notElem #-}
+--
+-- maximum :: Ord a => [a] -> a
+-- maximum = maximumS . stream
+-- {-# INLINE maximum #-}
+-- minimum :: Ord a => [a] -> a
+-- minimum = minimumS . stream
+-- {-# INLINE minimum #-}
+-- sum :: Num a => [a] -> a
+-- sum = sumS . stream
+-- {-# INLINE sum #-}
+-- product :: Num a => [a] -> a
+-- product = productS . stream
+-- {-# INLINE product #-}
+-- and :: [Bool] -> Bool
+-- and = andS . stream
+-- {-# INLINE and #-}
+-- or :: [Bool] -> Bool
+-- or = orS . stream
+-- {-# INLINE or #-}
+-- any :: (a -> Bool) -> [a] -> Bool
+-- any p = anyS p . stream
+-- {-# INLINE any #-}
+-- all :: (a -> Bool) -> [a] -> Bool
+-- all p = allS p . stream
+-- {-# INLINE all #-}
+--
+-- foldl1' :: (a -> a -> a) -> [a] -> a
+-- foldl1' f = foldl1S' f . stream
+-- {-# INLINE foldl1' #-}
+-- concat :: [[a]] -> [a]
+-- concat = unstream . concatS . stream
+-- {-# INLINE concat #-}
+-- concatMap :: (a -> [b]) -> [a] -> [b]
+-- concatMap f = unstream . concatMapS (stream . f) . stream
+-- {-# INLINE concatMap #-}
+--
+-- filter :: (a -> Bool) -> [a] -> [a]
+-- filter p = unstream . filterS p . stream
+-- {-# INLINE filter #-}
+-- lookup :: Eq a => a -> [(a, b)] -> Maybe b
+-- lookup x = lookupS x . stream
+-- {-# INLINE lookup #-}
+--
+-- head :: [a] -> a
+-- head = headS . stream
+-- {-# INLINE head #-}
+-- last :: [a] -> a
+-- last = lastS . stream
+-- {-# INLINE last #-}
+-- tail :: [a] -> [a]
+-- -- destoys sharing:
+-- -- tail = unstream . tailS . stream
+-- tail [] = errorEmptyList "tail"
+-- tail (_:xs) = xs
+-- {-# INLINE tail #-}
+-- init :: [a] -> [a]
+-- init = unstream . initS . stream
+-- {-# INLINE init #-}
+-- uncons :: [a] -> Maybe (a, [a])
+-- uncons [] = Nothing
+-- uncons (x:xs) = Just (x, xs)
+-- {-# NOINLINE [1] uncons #-}
+-- -- {-# RULES "uncons/stream" forall s. uncons (unstream s) = unconsS s #-}
+-- -- {-# RULES "uncons/stream" forall s. uncons (cheapUnstream s) = unconsS s #-}
+-- unsnoc :: [a] -> Maybe ([a], a)
+-- unsnoc = unsnocS . stream
+-- {-# INLINE unsnoc #-}
+-- (!?) :: [a] -> Int -> Maybe a
+-- xs !? i = indexS (stream xs) i
+-- {-# INLINE (!?) #-}
+-- (!!) :: [a] -> Int -> a
+-- xs !! i = unsafeIndexS (stream xs) i
+-- {-# INLINE (!!) #-}
+--
+-- scanl :: (b -> a -> b) -> b -> [a] -> [b]
+-- scanl k z = unstream . scanlS k z . stream
+-- {-# INLINE scanl #-}
+-- scanl1 :: (a -> a -> a) -> [a] -> [a]
+-- scanl1 k = unstream . scanl1S k . stream
+-- {-# INLINE scanl1 #-}
+-- scanl' :: (b -> a -> b) -> b -> [a] -> [b]
+-- scanl' k z = unstream . scanlS' k z . stream
+-- {-# INLINE scanl' #-}
+-- scanr :: (a -> b -> b) -> b -> [a] -> [b]
+-- scanr f q0 = foldrS (\x qs@(q:_) -> f x q : qs) [q0] . stream
+-- {-# INLINE scanr #-}
+-- scanr1 :: (a -> a -> a) -> [a] -> [a]
+-- scanr1 f = foldrS (\x qs -> case qs of [] -> [x]; (q:_) -> f x q : qs) [] . stream
+-- {-# INLINE scanr1 #-}
+--
+-- iterate :: (a -> a) -> a -> [a]
+-- iterate f x = cheapUnstream (iterateS f x)
+-- {-# INLINE iterate #-}
+-- iterate' :: (a -> a) -> a -> [a]
+-- iterate' f x = unstream (iterateS' f x)
+-- {-# INLINE iterate' #-}
+-- repeat :: a -> [a]
+-- repeat x = let xs = x : xs in xs
+-- -- repeat = cheapUnstream . repeatS
+-- {-# INLINE repeat #-}
+-- replicate :: Int -> a -> [a]
+-- replicate n x = cheapUnstream (replicateS n x)
+-- {-# INLINE replicate #-}
+-- cycle :: [a] -> [a]
+-- cycle xs = ys where ys = foldrS (:) ys (stream xs)
+-- -- cycle = unstream . cycleS . stream
+-- {-# INLINE cycle #-}
+--
+-- take :: Int -> [a] -> [a]
+-- take n = unstream . takeS n . stream
+-- {-# INLINE take #-}
+-- drop :: Int -> [a] -> [a]
+-- drop 0 xs = xs
+-- drop _ [] = []
+-- drop n (_:xs) = drop (n - 1) xs
+-- {-# NOINLINE [1] drop #-}
+-- -- {-# RULES "drop/stream" forall n s. drop n (unstream s) = unstream (dropS n s) #-}
+-- -- {-# RULES "drop/stream" forall n s. drop n (cheapUnstream s) = cheapUnstream (dropS n s) #-}
+--
+-- splitAt :: Int -> [a] -> ([a], [a])
+-- splitAt 0 xs = ([], xs)
+-- splitAt _ [] = ([],[])
+-- splitAt n (x:xs) = let (xs',ys') = splitAt (n - 1) xs in (x : xs', ys')
+-- {-# NOINLINE [1] splitAt #-}
+-- -- {-# RULES "splitAt/stream" forall n s. splitAt n (unstream s) = splitAtS n s #-}
+-- -- {-# RULES "splitAt/stream" forall n s. splitAt n (cheapUnstream s) = cheapSplitAtS n s #-}
+-- takeWhile :: (a -> Bool) -> [a] -> [a]
+-- takeWhile p = unstream . takeWhileS p . stream
+-- {-# INLINE takeWhile #-}
+-- dropWhile :: (a -> Bool) -> [a] -> [a]
+-- dropWhile _ [] = []
+-- dropWhile p xs@(x:xs')
+-- | p x = dropWhile p xs'
+-- | otherwise = xs
+-- {-# NOINLINE [1] dropWhile #-}
+-- -- {-# RULES "dropWhile/stream" forall p s. dropWhile p (unstream s) = unstream (dropWhileS p s) #-}
+-- -- {-# RULES "dropWhile/stream" forall p s. dropWhile p (cheapUnstream s) = unstream (dropWhileS p s) #-}
+-- span :: (a -> Bool) -> [a] -> ([a], [a])
+-- -- destroys sharing and duplicates work:
+-- -- span p xs = (unstream (takeWhileS p (stream xs)), unstream (dropWhileS p (stream xs)))
+-- span _ [] = ([], [])
+-- span p xs@(x:xs')
+-- | p x = let (ys,zs) = span p xs' in (x:ys,zs)
+-- | otherwise = ([], xs)
+-- {-# NOINLINE [1] span #-}
+-- -- {-# RULES "span/stream" forall p s. span p (unstream s) = spanS p s #-}
+-- -- {-# RULES "span/stream" forall p s. span p (cheapUnstream s) = spanS p s #-}
+-- break :: (a -> Bool) -> [a] -> ([a], [a])
+-- break p = span (not . p)
+-- {-# INLINE break #-}
+-- reverse :: [a] -> [a]
+-- reverse = reverseS . stream
+-- {-# INLINE reverse #-}
+--
+-- zip :: [a] -> [b] -> [(a,b)]
+-- zip xs ys = unstream (zipS (stream xs) (stream ys))
+-- {-# INLINE zip #-}
+-- zip3 :: [a] -> [b] -> [c] -> [(a,b,c)]
+-- zip3 xs ys zs = unstream (zip3S (stream xs) (stream ys) (stream zs))
+-- {-# INLINE zip3 #-}
+-- zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]
+-- zipWith f xs ys = unstream (zipWithS f (stream xs) (stream ys))
+-- {-# INLINE zipWith #-}
+-- zipWith3 :: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
+-- zipWith3 f xs ys zs = unstream (zipWith3S f (stream xs) (stream ys) (stream zs))
+-- {-# INLINE zipWith3 #-}
+--
+-- unzip :: [(a,b)] -> ([a], [b])
+-- unzip = unzipS . stream
+-- {-# INLINE unzip #-}
+-- unzip3 :: [(a,b,c)] -> ([a], [b], [c])
+-- unzip3 = unzip3S . stream
+-- {-# INLINE unzip3 #-}
+
+
-- $setup
-- >>> import GHC.Internal.Base
-- >>> import Prelude (Num (..), Ord (..), Int, Double, odd, not, undefined)
@@ -98,10 +1022,12 @@ badHead = errorEmptyList "head"
-- This rule is useful in cases like
-- head [y | (x,y) <- ps, x==t]
{-# RULES
-"head/build" forall (g::forall b.(a->b->b)->b->b) .
- head (build g) = g (\x _ -> x) badHead
-"head/augment" forall xs (g::forall b. (a->b->b) -> b -> b) .
- head (augment g xs) = g (\x _ -> x) (head xs)
+"head/unstream" forall s. head (unstream s) = headS s
+"head/cheapUnstream" forall s. head (cheapUnstream s) = headS s
+-- "head/build" forall (g::forall b.(a->b->b)->b->b) .
+-- head (build g) = g (\x _ -> x) badHead
+-- "head/augment" forall xs (g::forall b. (a->b->b) -> b -> b) .
+-- head (augment g xs) = g (\x _ -> x) (head xs)
#-}
-- | \(\mathcal{O}(1)\). Decompose a list into its 'head' and 'tail'.
@@ -283,8 +1209,9 @@ lenAcc [] n = n
lenAcc (_:ys) n = lenAcc ys (n+1)
{-# RULES
-"length" [~1] forall xs . length xs = foldr lengthFB idLength xs 0
-"lengthList" [1] foldr lengthFB idLength = lenAcc
+"length" length = lengthS . stream
+-- "length" [~1] forall xs . length xs = foldr lengthFB idLength xs 0
+-- "lengthList" [1] foldr lengthFB idLength = lenAcc
#-}
-- The lambda form turns out to be necessary to make this inline
@@ -325,9 +1252,10 @@ filterFB c p x r | p x = x `c` r
| otherwise = r
{-# RULES
-"filter" [~1] forall p xs. filter p xs = build (\c n -> foldr (filterFB c p) n xs)
-"filterList" [1] forall p. foldr (filterFB (:) p) [] = filter p
-"filterFB" forall c p q. filterFB (filterFB c p) q = filterFB c (\x -> q x && p x)
+"filter" forall p. filter p = unstream . filterS p . stream
+-- "filter" [~1] forall p xs. filter p xs = build (\c n -> foldr (filterFB c p) n xs)
+-- "filterList" [1] forall p. foldr (filterFB (:) p) [] = filter p
+-- "filterFB" forall c p q. filterFB (filterFB c p) q = filterFB c (\x -> q x && p x)
#-}
-- Note the filterFB rule, which has p and q the "wrong way round" in the RHS.
@@ -359,10 +1287,13 @@ filterFB c p x r | p x = x `c` r
-- >>> foldl (+) 0 [1..]
-- * Hangs forever *
foldl :: forall a b. (b -> a -> b) -> b -> [a] -> b
-{-# INLINE foldl #-}
-foldl k z0 xs =
- foldr (\(v::a) (fn::b->b) -> oneShot (\(z::b) -> fn (k z v))) (id :: b -> b) xs z0
- -- See Note [Left folds via right fold]
+foldl k z0 [] = z0
+foldl k z0 (x:xs) = foldl k (k z0 x) xs
+{-# NOINLINE [0] foldl #-}
+
+{-# RULES
+"foldl" forall k z . foldl k z = foldlS k z . stream
+ #-}
{-
Note [Left folds via right fold]
@@ -405,9 +1336,14 @@ allocation-free. Also see #13001.
-- | A strict version of 'foldl'.
foldl' :: forall a b . (b -> a -> b) -> b -> [a] -> b
-{-# INLINE foldl' #-}
-foldl' k z0 = \xs ->
- foldr (\(v::a) (fn::b->b) -> oneShot (\(z::b) -> z `seq` fn (k z v))) (id :: b -> b) xs z0
+foldl' k !z0 [] = z0
+foldl' k !z0 (x:xs) = foldl' k (k z0 x) xs
+
+{-# NOINLINE [0] foldl' #-}
+{-# RULES
+"foldl'" forall k z. foldl' k z = foldlS' k z . stream
+ #-}
+
{-
Note [Definition of foldl']
~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -551,10 +1487,11 @@ scanl = scanlGo
-- See Note [scanl rewrite rules]
{-# RULES
-"scanl" [~1] forall f a bs . scanl f a bs =
- build (\c n -> a `c` foldr (scanlFB f c) (constScanl n) bs a)
-"scanlList" [1] forall f (a::a) bs .
- foldr (scanlFB f (:)) (constScanl []) bs a = tail (scanl f a bs)
+"scanl" forall f a. scanl f a = unstream . scanlS f a . stream
+-- "scanl" [~1] forall f a bs . scanl f a bs =
+-- build (\c n -> a `c` foldr (scanlFB f c) (constScanl n) bs a)
+-- "scanlList" [1] forall f (a::a) bs .
+-- foldr (scanlFB f (:)) (constScanl []) bs a = tail (scanl f a bs)
#-}
{-# INLINE [0] scanlFB #-} -- See Note [Inline FB functions]
@@ -612,10 +1549,11 @@ scanl' = scanlGo'
-- See Note [scanl rewrite rules]
{-# RULES
-"scanl'" [~1] forall f a bs . scanl' f a bs =
- build (\c n -> a `c` foldr (scanlFB' f c) (flipSeq n) bs a)
-"scanlList'" [1] forall f a bs .
- foldr (scanlFB' f (:)) (flipSeq []) bs a = tail (scanl' f a bs)
+"scanl'" forall f a. scanl' f a = unstream . scanlS' f a . stream
+-- "scanl'" [~1] forall f a bs . scanl' f a bs =
+-- build (\c n -> a `c` foldr (scanlFB' f c) (flipSeq n) bs a)
+-- "scanlList'" [1] forall f a bs .
+-- foldr (scanlFB' f (:)) (flipSeq []) bs a = tail (scanl' f a bs)
#-}
{-# INLINE [0] scanlFB' #-} -- See Note [Inline FB functions]
@@ -680,6 +1618,7 @@ match on everything past the :, which is just the tail of scanl.
-- >>> foldr' (||) [False, False, True, True] -- Use foldr instead!
-- True
foldr' :: (a -> b -> b) -> b -> [a] -> b
+{-# INLINE foldr' #-}
foldr' f z0 xs = foldl f' id xs z0
where f' k x z = k $! f x z
@@ -704,6 +1643,9 @@ foldr1 f = go
go (x:xs) = f x (go xs)
go [] = errorEmptyList "foldr1"
{-# INLINE [0] foldr1 #-}
+{-# RULES
+"foldr1" forall f . foldr1 f = foldr1S f . stream
+ #-}
-- | \(\mathcal{O}(n)\). 'scanr' is the right-to-left dual of 'scanl'. Note that the order of parameters on the accumulating function are reversed compared to 'scanl'.
-- Also note that
@@ -746,11 +1688,12 @@ scanrFB f c = \x ~(r, est) -> (f x r, r `c` est)
-- See Note [scanrFB and evaluation] below
{-# RULES
-"scanr" [~1] forall f q0 ls . scanr f q0 ls =
- build (\c n -> strictUncurryScanr c (foldr (scanrFB f c) (q0,n) ls))
-"scanrList" [1] forall f q0 ls .
- strictUncurryScanr (:) (foldr (scanrFB f (:)) (q0,[]) ls) =
- scanr f q0 ls
+"scanr" forall f q0. scanr f q0 = scanrS f q0 . stream
+-- "scanr" [~1] forall f q0 ls . scanr f q0 ls =
+-- build (\c n -> strictUncurryScanr c (foldr (scanrFB f c) (q0,n) ls))
+-- "scanrList" [1] forall f q0 ls .
+-- strictUncurryScanr (:) (foldr (scanrFB f (:)) (q0,[]) ls) =
+-- scanr f q0 ls
#-}
{-
@@ -805,6 +1748,10 @@ scanr1 _ [] = []
scanr1 _ [x] = [x]
scanr1 f (x:xs) = f x q : qs
where qs@(q:_) = scanr1 f xs
+{-# NOINLINE [0] scanr1 #-}
+{-# RULES
+"scanr1" forall f. scanr1 f = scanr1S f . stream
+ #-}
-- | 'maximum' returns the maximum value from a list,
-- which must be non-empty, finite, and of an ordered type.
@@ -888,8 +1835,9 @@ iterateFB c f x0 = go x0
where go x = x `c` go (f x)
{-# RULES
-"iterate" [~1] forall f x. iterate f x = build (\c _n -> iterateFB c f x)
-"iterateFB" [1] iterateFB (:) = iterate
+"iterate" forall f x. iterate f x = unstream (iterateS f x)
+-- "iterate" [~1] forall f x. iterate f x = build (\c _n -> iterateFB c f x)
+-- "iterateFB" [1] iterateFB (:) = iterate
#-}
@@ -915,8 +1863,9 @@ iterate'FB c f x0 = go x0
in x' `seq` (x `c` go x')
{-# RULES
-"iterate'" [~1] forall f x. iterate' f x = build (\c _n -> iterate'FB c f x)
-"iterate'FB" [1] iterate'FB (:) = iterate'
+"iterate'" forall f x. iterate' f x = unstream (iterateS' f x)
+-- "iterate'" [~1] forall f x. iterate' f x = build (\c _n -> iterate'FB c f x)
+-- "iterate'FB" [1] iterate'FB (:) = iterate'
#-}
@@ -939,10 +1888,10 @@ repeatFB :: (a -> b -> b) -> a -> b
repeatFB c x = xs where xs = x `c` xs
-{-# RULES
-"repeat" [~1] forall x. repeat x = build (\c _n -> repeatFB c x)
-"repeatFB" [1] repeatFB (:) = repeat
- #-}
+-- {-# RULES
+-- "repeat" [~1] forall x. repeat x = build (\c _n -> repeatFB c x)
+-- "repeatFB" [1] repeatFB (:) = repeat
+-- #-}
-- | 'replicate' @n x@ is a list of length @n@ with @x@ the value of
-- every element.
@@ -959,9 +1908,12 @@ repeatFB c x = xs where xs = x `c` xs
--
-- >>> replicate 4 True
-- [True,True,True,True]
-{-# INLINE replicate #-}
+{-# NOINLINE [0] replicate #-}
replicate :: Int -> a -> [a]
replicate n x = take n (repeat x)
+{-# RULES
+"replicate" forall n x . replicate n x = cheapUnstream (replicateS n x)
+#-}
-- | 'cycle' ties a finite list into a circular one, or equivalently,
-- the infinite repetition of the original list. It is the identity
@@ -1027,11 +1979,12 @@ takeWhileFB p c n = \x r -> if p x then x `c` r else n
-- \x r -> if q x && p x then x `c` r else n =
-- takeWhileFB (\x -> q x && p x) c n
{-# RULES
-"takeWhile" [~1] forall p xs. takeWhile p xs =
- build (\c n -> foldr (takeWhileFB p c n) n xs)
-"takeWhileList" [1] forall p. foldr (takeWhileFB p (:) []) [] = takeWhile p
-"takeWhileFB" forall c n p q. takeWhileFB q (takeWhileFB p c n) n =
- takeWhileFB (\x -> q x && p x) c n
+"takeWhile" forall p. takeWhile p = unstream . takeWhileS p . stream
+-- "takeWhile" [~1] forall p xs. takeWhile p xs =
+-- build (\c n -> foldr (takeWhileFB p c n) n xs)
+-- "takeWhileList" [1] forall p. foldr (takeWhileFB p (:) []) [] = takeWhile p
+-- "takeWhileFB" forall c n p q. takeWhileFB q (takeWhileFB p c n) n =
+-- takeWhileFB (\x -> q x && p x) c n
#-}
-- | 'dropWhile' @p xs@ returns the suffix remaining after 'takeWhile' @p xs at .
@@ -1051,6 +2004,12 @@ dropWhile _ [] = []
dropWhile p xs@(x:xs')
| p x = dropWhile p xs'
| otherwise = xs
+{-# NOINLINE [0] dropWhile #-}
+
+{-# RULES
+"dropWhile/unstream" forall p s. dropWhile p (unstream s) = unstream (dropWhileS p s)
+"dropWhile/cheapUnstream" forall p s. dropWhile p (cheapUnstream s) = cheapUnstream (dropWhileS p s)
+ #-}
-- | 'take' @n@, applied to a list @xs@, returns the prefix of @xs@
-- of length @n@, or @xs@ itself if @n >= 'length' xs at .
@@ -1109,12 +2068,13 @@ unsafeTake 1 (x: _) = [x]
unsafeTake m (x:xs) = x : unsafeTake (m - 1) xs
{-# RULES
-"take" [~1] forall n xs . take n xs =
- build (\c nil -> if 0 < n
- then foldr (takeFB c nil) (flipSeq nil) xs n
- else nil)
-"unsafeTakeList" [1] forall n xs . foldr (takeFB (:) []) (flipSeq []) xs n
- = unsafeTake n xs
+"take" forall n. take n = unstream . takeS n . stream
+-- "take" [~1] forall n xs . take n xs =
+-- build (\c nil -> if 0 < n
+-- then foldr (takeFB c nil) (flipSeq nil) xs n
+-- else nil)
+-- "unsafeTakeList" [1] forall n xs . foldr (takeFB (:) []) (flipSeq []) xs n
+-- = unsafeTake n xs
#-}
{-# INLINE [0] flipSeq #-}
@@ -1168,7 +2128,7 @@ drop n xs | n <= 0 = xs
drop _ [] = []
drop n (_:xs) = drop (n-1) xs
#else /* hack away */
-{-# INLINE drop #-}
+{-# INLINE [1] drop #-}
drop n ls
| n <= 0 = ls
| otherwise = unsafeDrop n ls
@@ -1179,6 +2139,10 @@ drop n ls
unsafeDrop !_ [] = []
unsafeDrop 1 (_:xs) = xs
unsafeDrop m (_:xs) = unsafeDrop (m - 1) xs
+{-# RULES
+"drop/unstream" forall n s . drop n (unstream s) = unstream (dropS n s)
+"drop/cheapUnstream" forall n s. drop n (cheapUnstream s) = cheapUnstream (dropS n s)
+ #-}
#endif
-- | 'splitAt' @n xs@ returns a tuple where first element is @xs@ prefix of
@@ -1238,6 +2202,11 @@ splitAt n ls
splitAt' m (x:xs) = (x:xs', xs'')
where
(xs', xs'') = splitAt' (m - 1) xs
+{-# NOINLINE [0] splitAt #-}
+{-# RULES
+"splitAt/unstream" forall n s. splitAt n (unstream s) = splitAtS n s
+"splitAt/cheapUnstream" forall n s. splitAt n (cheapUnstream s) = cheapSplitAtS n s
+ #-}
#endif /* USE_REPORT_PRELUDE */
-- | 'span', applied to a predicate @p@ and a list @xs@, returns a tuple where
@@ -1394,8 +2363,9 @@ and (x:xs) = x && and xs
{-# NOINLINE [1] and #-}
{-# RULES
-"and/build" forall (g::forall b.(Bool->b->b)->b->b) .
- and (build g) = g (&&) True
+"and" and = andS . stream
+-- "and/build" forall (g::forall b.(Bool->b->b)->b->b) .
+-- and (build g) = g (&&) True
#-}
#endif
@@ -1431,8 +2401,9 @@ or (x:xs) = x || or xs
{-# NOINLINE [1] or #-}
{-# RULES
-"or/build" forall (g::forall b.(Bool->b->b)->b->b) .
- or (build g) = g (||) False
+"or" or = orS . stream
+-- "or/build" forall (g::forall b.(Bool->b->b)->b->b) .
+-- or (build g) = g (||) False
#-}
#endif
@@ -1468,8 +2439,9 @@ any p (x:xs) = p x || any p xs
{-# NOINLINE [1] any #-}
{-# RULES
-"any/build" forall p (g::forall b.(a->b->b)->b->b) .
- any p (build g) = g ((||) . p) False
+"any" forall p . any p = anyS p . stream
+-- "any/build" forall p (g::forall b.(a->b->b)->b->b) .
+-- any p (build g) = g ((||) . p) False
#-}
#endif
@@ -1505,8 +2477,9 @@ all p (x:xs) = p x && all p xs
{-# NOINLINE [1] all #-}
{-# RULES
-"all/build" forall p (g::forall b.(a->b->b)->b->b) .
- all p (build g) = g ((&&) . p) True
+"all" forall p . all p = allS p . stream
+-- "all/build" forall p (g::forall b.(a->b->b)->b->b) .
+-- all p (build g) = g ((&&) . p) True
#-}
#endif
@@ -1539,8 +2512,9 @@ elem _ [] = False
elem x (y:ys) = x==y || elem x ys
{-# NOINLINE [1] elem #-}
{-# RULES
-"elem/build" forall x (g :: forall b . (a -> b -> b) -> b -> b)
- . elem x (build g) = g (\ y r -> (x == y) || r) False
+"elem" forall x. elem x = elemS x . stream
+-- "elem/build" forall x (g :: forall b . (a -> b -> b) -> b -> b)
+-- . elem x (build g) = g (\ y r -> (x == y) || r) False
#-}
#endif
@@ -1570,8 +2544,9 @@ notElem _ [] = True
notElem x (y:ys)= x /= y && notElem x ys
{-# NOINLINE [1] notElem #-}
{-# RULES
-"notElem/build" forall x (g :: forall b . (a -> b -> b) -> b -> b)
- . notElem x (build g) = g (\ y r -> (x /= y) && r) True
+"notElem" forall x. notElem x = notElemS x . stream
+-- "notElem/build" forall x (g :: forall b . (a -> b -> b) -> b -> b)
+-- . notElem x (build g) = g (\ y r -> (x /= y) && r) True
#-}
#endif
@@ -1596,35 +2571,11 @@ lookup key ((x,y):xys)
| otherwise = lookup key xys
{-# NOINLINE [1] lookup #-} -- see Note [Fusion for lookup]
{-# RULES
-"lookup/build" forall x (g :: forall b. ((k, a) -> b -> b) -> b -> b).
- lookup x (build g) = g (\(k, v) r -> if x == k then Just v else r) Nothing
+"lookup" forall x. lookup x = lookupS x . stream
+-- "lookup/build" forall x (g :: forall b. ((k, a) -> b -> b) -> b -> b).
+-- lookup x (build g) = g (\(k, v) r -> if x == k then Just v else r) Nothing
#-}
--- | Map a function returning a list over a list and concatenate the results.
--- 'concatMap' can be seen as the composition of 'concat' and 'map'.
---
--- > concatMap f xs == (concat . map f) xs
---
--- ==== __Examples__
---
--- >>> concatMap (\i -> [-i,i]) []
--- []
---
--- >>> concatMap (\i -> [-i, i]) [1, 2, 3]
--- [-1,1,-2,2,-3,3]
---
--- >>> concatMap ('replicate' 3) [0, 2, 4]
--- [0,0,0,2,2,2,4,4,4]
-concatMap :: (a -> [b]) -> [a] -> [b]
-concatMap f = foldr ((++) . f) []
-
-{-# NOINLINE [1] concatMap #-}
-
-{-# RULES
-"concatMap" forall f xs . concatMap f xs =
- build (\c n -> foldr (\x b -> foldr c b (f x)) n xs)
- #-}
-
-- | Concatenate a list of lists.
--
@@ -1644,8 +2595,9 @@ concat = foldr (++) []
{-# NOINLINE [1] concat #-}
{-# RULES
- "concat" forall xs. concat xs =
- build (\c n -> foldr (\x y -> foldr c y x) n xs)
+"concat" concat = unstream . concatS . stream
+-- "concat" forall xs. concat xs =
+-- build (\c n -> foldr (\x y -> foldr c y x) n xs)
-- We don't bother to turn non-fusible applications of concat back into concat
#-}
@@ -1694,9 +2646,17 @@ negIndex = error $ prel_list_str ++ "!!: negative index"
{-# INLINABLE (!!) #-}
xs !! n
| n < 0 = negIndex
- | otherwise = foldr (\x r k -> case k of
- 0 -> x
- _ -> r (k-1)) tooLarge xs n
+ | otherwise = unsafeIndexHelper xs n
+
+unsafeIndexHelper :: [a] -> Int -> a
+unsafeIndexHelper [] i = tooLarge i
+unsafeIndexHelper (x:xs) 0 = x
+unsafeIndexHelper (x:xs) n = unsafeIndexHelper xs (n - 1)
+{-# NOINLINE [1] unsafeIndexHelper #-}
+
+{-# RULES
+"unsafeIndexHelper" forall xs. unsafeIndexHelper xs = unsafeIndexHelperS (stream xs)
+ #-}
#endif
-- | List index (subscript) operator, starting from 0. Returns 'Nothing'
@@ -1724,9 +2684,16 @@ xs !! n
{-# INLINABLE (!?) #-}
xs !? n
| n < 0 = Nothing
- | otherwise = foldr (\x r k -> case k of
- 0 -> Just x
- _ -> r (k-1)) (const Nothing) xs n
+ | otherwise = indexHelper xs n
+
+indexHelper :: [a] -> Int -> Maybe a
+indexHelper [] _ = Nothing
+indexHelper (x:_) 0 = Just x
+indexHelper (_:xs) n = indexHelper xs (n - 1)
+{-# NOINLINE [1] indexHelper #-}
+{-# RULES
+"indexHelper" forall xs n . indexHelper xs n = indexHelperS (stream xs) n
+ #-}
--------------------------------------------------------------
-- The zip family
@@ -1879,8 +2846,9 @@ zipFB :: ((a, b) -> c -> d) -> a -> b -> c -> d
zipFB c = \x y r -> (x,y) `c` r
{-# RULES -- See Note [Fusion for zipN/zipWithN]
-"zip" [~1] forall xs ys. zip xs ys = build (\c n -> foldr2 (zipFB c) n xs ys)
-"zipList" [1] foldr2 (zipFB (:)) [] = zip
+"zip" forall xs ys. zip xs ys = unstream (zipS (stream xs) (stream ys))
+-- "zip" [~1] forall xs ys. zip xs ys = build (\c n -> foldr2 (zipFB c) n xs ys)
+-- "zipList" [1] foldr2 (zipFB (:)) [] = zip
#-}
----------------------------------------------
@@ -1900,8 +2868,9 @@ zip3FB :: ((a,b,c) -> xs -> xs') -> a -> b -> c -> xs -> xs'
zip3FB cons = \a b c r -> (a,b,c) `cons` r
{-# RULES -- See Note [Fusion for zipN/zipWithN]
-"zip3" [~1] forall as bs cs. zip3 as bs cs = build (\c n -> foldr3 (zip3FB c) n as bs cs)
-"zip3List" [1] foldr3 (zip3FB (:)) [] = zip3
+"zip3" forall xs ys zs . zip3 xs ys zs = unstream (zip3S (stream xs) (stream ys) (stream zs))
+-- "zip3" [~1] forall as bs cs. zip3 as bs cs = build (\c n -> foldr3 (zip3FB c) n as bs cs)
+-- "zip3List" [1] foldr3 (zip3FB (:)) [] = zip3
#-}
-- The zipWith family generalises the zip family by zipping with the
@@ -1949,8 +2918,9 @@ zipWithFB :: (a -> b -> c) -> (d -> e -> a) -> d -> e -> b -> c
zipWithFB c f = \x y r -> (x `f` y) `c` r
{-# RULES -- See Note [Fusion for zipN/zipWithN]
-"zipWith" [~1] forall f xs ys. zipWith f xs ys = build (\c n -> foldr2 (zipWithFB c f) n xs ys)
-"zipWithList" [1] forall f. foldr2 (zipWithFB (:) f) [] = zipWith f
+"zipWith" forall f xs ys. zipWith f xs ys = unstream (zipWithS f (stream xs) (stream ys))
+-- "zipWith" [~1] forall f xs ys. zipWith f xs ys = build (\c n -> foldr2 (zipWithFB c f) n xs ys)
+-- "zipWithList" [1] forall f. foldr2 (zipWithFB (:) f) [] = zipWith f
#-}
-- | \(\mathcal{O}(\min(l,m,n))\). The 'zipWith3' function takes a function which combines three
@@ -1981,8 +2951,9 @@ zipWith3FB :: (d -> xs -> xs') -> (a -> b -> c -> d) -> a -> b -> c -> xs -> xs'
zipWith3FB cons func = \a b c r -> (func a b c) `cons` r
{-# RULES
-"zipWith3" [~1] forall f as bs cs. zipWith3 f as bs cs = build (\c n -> foldr3 (zipWith3FB c f) n as bs cs)
-"zipWith3List" [1] forall f. foldr3 (zipWith3FB (:) f) [] = zipWith3 f
+"zipWith3" forall f xs ys zs . zipWith3 f xs ys zs = unstream (zipWith3S f (stream xs) (stream ys) (stream zs))
+-- "zipWith3" [~1] forall f as bs cs. zipWith3 f as bs cs = build (\c n -> foldr3 (zipWith3FB c f) n as bs cs)
+-- "zipWith3List" [1] forall f. foldr3 (zipWith3FB (:) f) [] = zipWith3 f
#-}
-- | 'unzip' transforms a list of pairs into a list of first components
=====================================
libraries/ghc-internal/src/GHC/Internal/System/Posix/Internals.hs
=====================================
@@ -48,7 +48,7 @@ import GHC.Internal.Data.Maybe
import GHC.Internal.System.IO.Error
#endif
-import GHC.Internal.Base
+import GHC.Internal.Base hiding (Stream)
import GHC.Internal.Bits
import GHC.Internal.Num
import GHC.Internal.Real
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3e0b4233f722dedd7ebcfb0be0ca0adef8de0574
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3e0b4233f722dedd7ebcfb0be0ca0adef8de0574
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