diff --git a/Data/Stream.hs b/Data/Stream.hs --- a/Data/Stream.hs +++ b/Data/Stream.hs @@ -81,7 +81,7 @@ infixr 5 `Cons` instance Functor Stream where - fmap f (Cons x xs) = Cons (f x) (fmap f xs) + fmap f ~(Cons x xs) = Cons (f x) (fmap f xs) instance Applicative Stream where pure = repeat @@ -92,7 +92,7 @@ xs >>= f = join (fmap f xs) where join :: Stream (Stream a) -> Stream a - join (Cons xs xss) = Cons (head xs) (join (map tail xss)) + join ~(Cons xs xss) = Cons (head xs) (join (map tail xss)) instance Arbitrary a => Arbitrary (Stream a) where arbitrary = liftM2 Cons arbitrary arbitrary @@ -129,7 +129,7 @@ -- | Extract the sequence following the head of the stream. tail :: Stream a -> Stream a -tail (Cons _ xs) = xs +tail ~(Cons _ xs) = xs -- | The 'inits' function takes a stream @xs@ and returns all the -- finite prefixes of @xs@. @@ -152,25 +152,25 @@ -- | Apply a function uniformly over all elements of a sequence. map :: (a -> b) -> Stream a -> Stream b -map f (Cons x xs) = Cons (f x) (map f xs) +map f ~(Cons x xs) = Cons (f x) (map f xs) -- | 'intersperse' @y@ @xs@ creates an alternating stream of -- elements from @xs@ and @y@. intersperse :: a -> Stream a -> Stream a -intersperse y (Cons x xs) = Cons x (Cons y (intersperse y xs)) +intersperse y ~(Cons x xs) = Cons x (Cons y (intersperse y xs)) -- | Interleave two Streams @xs@ and @ys@, alternating elements -- from each list. -- -- > [x1,x2,...] `interleave` [y1,y2,...] == [x1,y1,x2,y2,...] interleave :: Stream a -> Stream a -> Stream a -interleave (Cons x xs) ys = Cons x (interleave ys xs) +interleave ~(Cons x xs) ys = Cons x (interleave ys xs) -- | 'scan' yields a stream of successive reduced values from: -- -- > scan f z [x1, x2, ...] == [z, z `f` x1, (z `f` x1) `f` x2, ...] scan :: (a -> b -> a) -> a -> Stream b -> Stream a -scan f z (Cons x xs) = z <:> scan f (f z x) xs +scan f z ~(Cons x xs) = z <:> scan f (f z x) xs -- | @scan'@ is a strict scan. scan' :: (a -> b -> a) -> a -> Stream b -> Stream a @@ -180,15 +180,15 @@ -- -- > scan1 f [x1, x2, ...] == [x1, x1 `f` x2, ...] scan1 :: (a -> a -> a) -> Stream a -> Stream a -scan1 f (Cons x xs) = scan f x xs +scan1 f ~(Cons x xs) = scan f x xs -- | @scan1'@ is a strict scan that has no starting value. scan1' :: (a -> a -> a) -> Stream a -> Stream a -scan1' f (Cons x xs) = scan' f x xs +scan1' f ~(Cons x xs) = scan' f x xs -- | 'transpose' computes the transposition of a stream of streams. transpose :: Stream (Stream a) -> Stream (Stream a) -transpose (Cons (Cons x xs) yss) = +transpose ~(Cons (Cons x xs) yss) = (x <:> map head yss) <:> transpose (xs <:> map tail yss) -- | 'iterate' @f@ @x@ function produces the infinite sequence @@ -263,7 +263,7 @@ -- /Beware/: this function may diverge if every element of @xs@ -- satisfies @p@, e.g. @dropWhile even (repeat 0)@ will loop. dropWhile :: (a -> Bool) -> Stream a -> Stream a -dropWhile p (Cons x xs) +dropWhile p ~(Cons x xs) | p x = dropWhile p xs | otherwise = Cons x xs @@ -284,7 +284,7 @@ -- /Beware/: this function may diverge if there is no element of -- @xs@ that satisfies @p@, e.g. @filter odd (repeat 0)@ will loop. filter :: (a -> Bool) -> Stream a -> Stream a -filter p (Cons x xs) +filter p ~(Cons x xs) | p x = Cons x (filter p xs) | otherwise = filter p xs @@ -297,7 +297,7 @@ -- example, @fst (partition even (repeat 0)) == repeat 0@; on the -- other hand @snd (partition even (repeat 0))@ is undefined. partition :: (a -> Bool) -> Stream a -> (Stream a, Stream a) -partition p (Cons x xs) = +partition p ~(Cons x xs) = let (trues,falses) = partition p xs in if p x then (Cons x trues, falses) else (trues, Cons x falses) @@ -309,7 +309,7 @@ -- -- > group $ cycle "Mississippi" = "M" ::: "i" ::: "ss" ::: "i" ::: "ss" ::: "i" ::: "pp" ::: "i" ::: "M" ::: "i" ::: ... group :: Eq a => Stream a -> Stream [a] -group (Cons x ys) = let (xs, zs) = span (\y -> x == y) ys +group ~(Cons x ys) = let (xs, zs) = span (\y -> x == y) ys in (x : xs) <:> group zs -- | The 'isPrefix' function returns @True@ if the first argument is @@ -376,17 +376,17 @@ -- | The 'zip' function takes two streams and returns a list of -- corresponding pairs. zip :: Stream a -> Stream b -> Stream (a,b) -zip (Cons x xs) (Cons y ys) = Cons (x,y) (zip xs ys) +zip ~(Cons x xs) ~(Cons y ys) = Cons (x,y) (zip xs ys) -- | The 'zipWith' function generalizes 'zip'. Rather than tupling -- the functions, the elements are combined using the function -- passed as the first argument to 'zipWith'. zipWith :: (a -> b -> c) -> Stream a -> Stream b -> Stream c -zipWith f (Cons x xs) (Cons y ys) = Cons (f x y) (zipWith f xs ys) +zipWith f ~(Cons x xs) ~(Cons y ys) = Cons (f x y) (zipWith f xs ys) -- | The 'unzip' function is the inverse of the 'zip' function. unzip :: Stream (a,b) -> (Stream a, Stream b) -unzip (Cons (x,y) xys) = (Cons x (fst (unzip xys)), +unzip ~(Cons (x,y) xys) = (Cons x (fst (unzip xys)), Cons y (snd (unzip xys))) -- | The 'words' function breaks a stream of characters into a @@ -401,7 +401,7 @@ -- | The 'unwords' function is an inverse operation to 'words'. It -- joins words with separating spaces. unwords :: Stream String -> Stream Char -unwords (Cons x xs) = foldr Cons (Cons ' ' (unwords xs)) x +unwords ~(Cons x xs) = foldr Cons (Cons ' ' (unwords xs)) x -- | The 'lines' function breaks a stream of characters into a list -- of strings at newline characters. The resulting strings do not @@ -416,7 +416,7 @@ -- | The 'unlines' function is an inverse operation to 'lines'. It -- joins lines, after appending a terminating newline to each. unlines :: Stream String -> Stream Char -unlines (Cons x xs) = foldr Cons (Cons '\n' (unlines xs)) x +unlines ~(Cons x xs) = foldr Cons (Cons '\n' (unlines xs)) x -- | The 'toList' converts a stream into an infinite list. toList :: Stream a -> [a] diff --git a/Stream.cabal b/Stream.cabal --- a/Stream.cabal +++ b/Stream.cabal @@ -1,5 +1,5 @@ Name: Stream -Version: 0.3.2 +Version: 0.4 License: BSD3 License-file: LICENSE Author: Wouter Swierstra ,