+++ /dev/null
-import "JavaBuiltin" as Java\r
-\r
-data Either a b = Left a | Right b\r
-\r
-data Stream a = Stream (s -> Step a s) s\r
-data Step a s = Done | Yield a s | Skip s\r
-\r
-// stream :: [a] -> Stream a\r
-// unstream :: Stream a -> [a] \r
-// streamRev :: [a] -> Stream a\r
-// unstreamRev :: Stream a -> [a]\r
-\r
-//toStream :: [a] -> Stream a\r
-//toStream l = Stream (\i -> if i >= length l then Done else Yield (get l i) (i+1)) 0\r
-\r
-filterS :: (a -> Boolean) -> Stream a -> Stream a\r
-filterS p (Stream next0 s0) = Stream next s0\r
- where\r
- next s = match next s with\r
- Done -> Done\r
- Skip s -> Skip s \r
- Yield a s -> if p a then Yield a s else Skip s\r
-\r
-mapS :: (a -> b) -> Stream a -> Stream b\r
-mapS f (Stream next0 s0) = Stream next s0\r
- where\r
- next s = match next0 s with\r
- Done -> Done\r
- Skip s -> Skip s \r
- Yield a s -> Yield (f a) s\r
- \r
-appendS :: Stream a -> Stream a -> Stream a\r
-appendS (Stream next1 s1) (Stream next2 s2) = Stream next (Left s1)\r
- where\r
- next (Left s) = match next1 s with\r
- Done -> Skip (Right s2)\r
- Skip s -> Skip (Left s) \r
- Yield a s -> Yield a (Left s)\r
- next (Right s) = match next2 s with\r
- Done -> Done\r
- Skip s -> Skip (Right s) \r
- Yield a s -> Yield a (Right s) \r
-\r
-decomposeS :: Stream a -> Maybe (a, Stream a)\r
-decomposeS (Stream next s0) = loop s0\r
- where\r
- loop s = match next s with\r
- Done -> Nothing\r
- Skip s -> loop s\r
- Yield a s -> Just (a, Stream next s) \r
-\r
-returnS :: a -> Stream a\r
-returnS x = Stream next True\r
- where \r
- next True = Yield x False\r
- next False = Done\r
- \r
-isEmptyS :: Stream a -> Boolean \r
-isEmptyS (Stream next s0) = loop s0\r
- where\r
- loop s = match next s with\r
- Done -> True\r
- Skip s -> loop s \r
- Yield _ _ -> False\r
- \r
-foldlS :: (a -> b -> a) -> a -> Stream b -> a\r
-foldlS f init (Stream next s0) = go init s0\r
- where\r
- go cur s = match next s with\r
- Done -> cur\r
- Skip s -> go cur s\r
- Yield x s -> go (f cur x) s\r
- \r
-scanlS :: (a -> b -> a) -> a -> Stream b -> Stream a\r
-scanlS f init (Stream next0 s0) = Stream next (s0, init)\r
- where\r
- next (s,v) = match next0 s with\r
- Done -> Done\r
- Skip s -> Skip (s, v)\r
- Yield x s -> Yield v (s, f v x) \r
- \r
-concatMapS :: (a -> Stream b) -> Stream a -> Stream b\r
-concatMapS f (Stream next0 s0) = Stream next (s0, Nothing)\r
- where\r
- next (s, Nothing) = match next0 s with\r
- Done -> Done\r
- Skip s -> Skip (s, Nothing)\r
- Yield x s -> Skip (s, Just (f x))\r
- next (s0, Just (Stream next1 s1)) = match next1 s1 with\r
- Done -> Skip (s0, Nothing)\r
- Skip s -> Skip (s0, Just (Stream next1 s))\r
- Yield x s -> Yield x (s0, Just (Stream next1 s))\r
-\r
-zipWithS :: (a -> b -> c) -> Stream a -> Stream b -> Stream c\r
-zipWithS f (Stream next0 s0) (Stream next1 s1) = Stream next (s0, s1, Nothing)\r
- where\r
- next (s0, s1, Nothing) = match next0 s0 with\r
- Done -> Done\r
- Skip s -> Skip (s, s1, Nothing)\r
- Yield x s -> Skip (s, s1, Just x)\r
- next (s0, s1, Just x) = match next1 s1 with\r
- Done -> Done\r
- Skip s -> Skip (s0, s, Just x)\r
- Yield y s -> Yield (f x y) (s0, s, Nothing)\r
-\r
-guardS :: Boolean -> Stream a -> Stream a\r
-guardS b (Stream next0 s0) = Stream next (b, s0)\r
- where\r
- next (False, _) = Done\r
- next (True, s) = match next0 s with\r
- Done -> Done\r
- Skip s -> Skip (True, s)\r
- Yield x s -> Yield x (True, s)\r
-/*\r
-takeS :: Integer -> Stream a -> Stream a\r
-takeS count (Stream next0 s0) = Stream next (count, s0)\r
- where\r
- next (count, s) = if count <= 0 then Done\r
- else match next0 s with\r
- Done -> Done\r
- | Skip s -> Skip (count, s)\r
- | Yield x s -> Yield x (count, s)\r
-*/\r
-repeatS :: a -> Stream a\r
-repeatS v = Stream next ()\r
- where\r
- next () = Yield v ()\r
-\r
-iterateS :: (a -> a) -> a -> Stream a\r
-iterateS f v = Stream next v\r
- where\r
- next v = Yield v (f v)\r
- \r
-main :: Integer\r
-main = foldlS Java.iadd (0 :: Integer) \r
- (appendS (appendS (returnS (1 :: Integer)) \r
- (returnS (2 :: Integer))) (returnS (3 :: Integer)))\r
---\r
-6
\ No newline at end of file