Catana (empty) → 0.1

raw patch · 4 files changed

+232/−0 lines, 4 filesdep +basedep +mtlsetup-changed

Dependencies added: base, mtl

Files

Catana.cabal +58/−0
Control/Monad/Catana.hs +142/−0
LICENSE +30/−0
Setup.hs +2/−0

+ Catana.cabal view

@@ -0,0 +1,58 @@+-- Catana.cabal auto-generated by cabal init. For additional+-- options, see+-- http://www.haskell.org/cabal/release/cabal-latest/doc/users-guide/authors.html#pkg-descr.+-- The name of the package.+Name:                Catana++-- The package version. See the Haskell package versioning policy+-- (http://www.haskell.org/haskellwiki/Package_versioning_policy) for+-- standards guiding when and how versions should be incremented.+Version:             0.1++-- A short (one-line) description of the package.+Synopsis: A monad for complex manipulation of a stream.          ++-- A longer description of the package.+Description: A monad for complex manipulation of a stream.        ++-- The license under which the package is released.+License:             BSD3++-- The file containing the license text.+License-file:        LICENSE++-- The package author(s).+Author:              Dustin DeWeese++-- An email address to which users can send suggestions, bug reports,+-- and patches.+Maintainer:          dustin.deweese@gmail.com++-- A copyright notice.+-- Copyright:           ++Category:            Control++Build-type:          Simple++-- Extra files to be distributed with the package, such as examples or+-- a README.+-- Extra-source-files:  ++-- Constraint on the version of Cabal needed to build this package.+Cabal-version:       >=1.2+++Library+  -- Modules exported by the library.+  Exposed-modules:     Control.Monad.Catana+  +  -- Packages needed in order to build this package.+  Build-depends: base >= 4 && < 5, mtl     +  +  -- Modules not exported by this package.+  -- Other-modules:       +  +  -- Extra tools (e.g. alex, hsc2hs, ...) needed to build the source.+  -- Build-tools:         +

+ Control/Monad/Catana.hs view

@@ -0,0 +1,142 @@+{- |+Module      : Control.Monad.Catana+Copyright   : (c) Dustin DeWeese 2011+License     : BSD3+Maintainer  : dustin.deweese@gmail.com+Stability   : experimental+Portability : portable++[Computation type:] Computations that both consume and produce elements lazily with support for advanced control flow using continuations++[Binding Strategy:] Binding a function to a monadic value produces a continuation which passes the unconsumed input and the combined output function in turn to the next continuation.++[Useful for:] Lazily processing a list with complex control structures.++[Zero and plus:] None.++[Example type:] @'Catana' i o b a@++The Catana monad represents computations that are both catamorphisms and anamorphisms; they both consume and produce values.  In addition, the Catana monad represents the computation in continuation-passing style, allowing the continuations to be manipulated as is Control.Monad.Cont+-}++module Control.Monad.Catana (+    -- * The Catana monad+    Catana(..),+    consume,+    top,+--    consumeOnly, -- too dangerous+    push,+    produce,+    stop,+    more,+    evalCatana,+    evalCatana'+    -- * Example 1: Usage of the Catana monad+    -- $catanaExample1+  ) where++import Control.Applicative+import Control.Monad+import Control.Monad.Cont++{- $catanaExample1++An example of complex control structure using Catana:++>catanaExample1 =+>  forever $ do+>    z <- callCC $ \exit -> do+>      (x, y) <- (,) <$> consume <*> consume+>      produce (x + y)+>      produce (x * y)+>      if x > 1+>        then exit 0+>        else do+>          produce (x - y)+>          produce (x / y)+>          return 1+>    produce z++Catana monads can be converted into a function over lists using 'evalCatana'.++> evalCatana catanaExample1 [1..4]+> -- result: [3.0,2.0,-1.0,0.5,1.0,7.0,12.0,0.0] +-}++data Catana i o b a = Catana { runCatana :: [i] -> (CatanaIO i o a -> CatanaIO i o b) -> CatanaIO i o b }+type CatanaIO i o a = (a, [i], [o] -> [o])++instance Functor (Catana i o b) where+  fmap f (Catana l) = Catana $ \i k ->+                      l i $ \(x, i', o') ->+                      k (f x, i', o')++instance Applicative (Catana i o b) where+  Catana fl <*> x = Catana $ \i k ->+                    fl i $ \(f, i', o1) ->+                      let (x', i'', o2) = runCatana (fmap f x) i' k+                        in (x', i'', o1 . o2)+  pure x = Catana $ \i k -> k (x, i, id)++instance Monad (Catana i o b) where+  return = pure+  Catana l >>= f = Catana $ \i k ->+                   l i $ \(x, i', o1) ->+                     let (x', i'', o2) = runCatana (f x) i' k+                       in (x', i'', o1 . o2)++instance MonadCont (Catana i o b) where+  callCC f = Catana $ \i k ->+               let g x = Catana $ \i' _ -> k (x, i', id)+                 in runCatana (f g) i k++-- |Consumes an element from the input list, returning it+-- If there is no more input, the chain of continuations ends+-- immediately; no more computations will be processed+consume :: Catana i o a i+consume = Catana f+  where f (x : i) k = k (x, i, id)+        f i k = (undefined, i, id)++-- |Returns the next input without consuming it+top :: Catana i o a i+top = Catana f+  where f i@(x : _) k = k (x, i, id)+        f i k = (undefined, i, id)++-- |Consumes only the element satisfying p, leaving the other+-- elements in the input list.  This could cause space leaks if+-- the input is never fully consumed+consumeOnly :: (i -> Bool) -> Catana i o a i+consumeOnly p = Catana f+  where f i k | null b = (undefined, i, id)+              | otherwise = k (head b, a ++ tail b, id)+          where (a, b) = span (not . p) i++-- |Stops computation, ending the continuation chain+stop :: Catana i o () a+stop = Catana $ \i k -> ((), i, id)++-- |Tests for more input+more :: Catana i o a Bool+more = Catana f+  where f [] k = k (False, [], id)+        f i k = k (True, i, id)++-- |Pushes 'x' into the input+push :: i -> Catana i o a ()+push x = Catana $ \i k -> k ((), x:i, id)++-- |Produces 'x' in the output+produce :: o -> Catana i o a ()+produce x = Catana $ \i k -> k ((), i, (x:))++-- |Converts a Catana monad into a function over lists+evalCatana :: Catana i o a a -> [i] -> [o]+evalCatana c i = o []+  where (_, _, o) = runCatana c i id++-- |Evaluates a Catana monad over a list returning the result and output+evalCatana' :: Catana i o a a -> [i] -> (a, [o])+evalCatana' c i = (x, o [])+  where (x, _, o) = runCatana c i id

+ LICENSE view

@@ -0,0 +1,30 @@+Copyright (c)2011, Dustin DeWeese++All rights reserved.++Redistribution and use in source and binary forms, with or without+modification, are permitted provided that the following conditions are met:++    * Redistributions of source code must retain the above copyright+      notice, this list of conditions and the following disclaimer.++    * Redistributions in binary form must reproduce the above+      copyright notice, this list of conditions and the following+      disclaimer in the documentation and/or other materials provided+      with the distribution.++    * Neither the name of Dustin DeWeese nor the names of other+      contributors may be used to endorse or promote products derived+      from this software without specific prior written permission.++THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+ Setup.hs view

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain