stream-monad 0.1.1.0 → 0.2

raw patch · 2 files changed

+36/−15 lines, 2 files

Files

• Control/Monad/Stream.hs +34/−13
• stream-monad.cabal +2/−2

@@ -34,6 +34,13 @@ --  data Stream a = Nil | Single a | Cons a (Stream a) | Susp (Stream a) +instance Functor Stream+ where+  fmap _ Nil         = Nil+  fmap f (Single x)  = Single (f x)+  fmap f (Cons x xs) = Cons (f x) (fmap f xs)+  fmap f (Susp xs)   = Susp (fmap f xs)+ -- | -- Suspensions can be used to ensure fairness. -- @@ -65,18 +72,32 @@  where   mzero = Nil -  Nil       `mplus` ys = suspended ys             -- suspending-  Single x  `mplus` ys = Cons x ys-  Cons x xs `mplus` ys = Cons x (ys `mplus` xs)   -- interleaving-  Susp xs   `mplus` ys = ys `splus` xs            -- using `splus`+  Nil       `mplus` ys        = suspended ys                -- suspending+  Single x  `mplus` ys        = Cons x ys+  Cons x xs `mplus` ys        = Cons x (ys `mplus` xs)      -- interleaving+  xs        `mplus` Nil       = xs+  Susp xs   `mplus` Single y  = Cons y xs+  Susp xs   `mplus` Cons y ys = Cons y (xs `mplus` ys)+  Susp xs   `mplus` Susp ys   = suspended (xs `mplus` ys) --- The function `splus` is similar to `mplus` but suspends its result--- if the first argument is a suspension. It uses `mplus` in recursive--- calls.----splus :: Stream a -> Stream a -> Stream a-Nil       `splus` ys = suspended ys-Single x  `splus` ys = Cons x ys-Cons x xs `splus` ys = Cons x (ys `mplus` xs)-Susp xs   `splus` ys = suspended (ys `mplus` xs)  -- suspending+-- |+-- The class @MonadTimes@ defines an operation to compute the+-- cartesian product of the results of two monadic operations.  A+-- sequential default implementation is given in terms of @>>=@ but+-- specific instances can ovverride this definition to evaluate both+-- arguments in parallel or interleaved.+-- +class Monad m => MonadTimes m+ where+  mtimes :: m a -> m b -> m (a,b)+  mtimes = liftM2 (,) +instance MonadTimes Stream+ where+  Nil       `mtimes` _         = Nil+  Single x  `mtimes` ys        = fmap (\y -> (x,y)) ys      -- or use liftM ?+  Cons x xs `mtimes` ys        = fmap (\y -> (x,y)) ys `mplus` (xs `mtimes` ys)+  _         `mtimes` Nil       = Nil+  Susp xs   `mtimes` Single y  = fmap (\x -> (x,y)) xs+  Susp xs   `mtimes` Cons y ys = fmap (\x -> (x,y)) xs `mplus` (xs `mtimes` ys)+  Susp xs   `mtimes` Susp ys   = suspended (xs `mtimes` ys)

@@ -1,5 +1,5 @@ Name:          stream-monad-Version:       0.1.1.0+Version:       0.2 Cabal-Version: >= 1.6 Synopsis:      Simple, Fair and Terminating Backtracking Monad Description:   This Haskell library provides an implementation of the@@ -11,7 +11,7 @@ Category:      Control, Monads License:       PublicDomain License-File:  LICENSE-Author:        Oleg Kiselyov+Author:        Oleg Kiselyov, Sebastian Fischer Maintainer:    Sebastian Fischer (sebf@informatik.uni-kiel.de) Bug-Reports:   mailto:sebf@informatik.uni-kiel.de Homepage:      http://github.com/sebfisch/stream-monad