Ticket #1773: Compositor.dpatch

New patches:

[new Control.Compositor module
Ashley Yakeley <ashley@semantic.org>**20071013074851
 
 The Compositor class is a superclass of Arrow.
] {
addfile ./Control/Compositor.hs
hunk ./Control/Applicative.hs 42
+import Control.Compositor
hunk ./Control/Applicative.hs 44
-       (Arrow(arr, (>>>), (&&&)), ArrowZero(zeroArrow), ArrowPlus((<+>)))
+       (Arrow(arr, (&&&)), ArrowZero(zeroArrow), ArrowPlus((<+>)))
hunk ./Control/Arrow.hs 28
-               (<<<), (<<^), (^<<),
+               (<<^), (^<<),
hunk ./Control/Arrow.hs 43
+import Control.Compositor
hunk ./Control/Arrow.hs 50
-infixr 1 >>>, ^>>, >>^
-infixr 1 <<<, ^<<, <<^
+infixr 1 ^>>, >>^
+infixr 1 ^<<, <<^
hunk ./Control/Arrow.hs 55
---   as well as '>>>' and 'first'.  The other combinators have sensible
+--   as well as 'first'.  The other combinators have sensible
hunk ./Control/Arrow.hs 58
-class Arrow a where
+class Compositor a => Arrow a where
hunk ./Control/Arrow.hs 69
-       -- | Left-to-right composition of arrows.
-       (>>>) :: a b c -> a c d -> a b d
-
hunk ./Control/Arrow.hs 98
+"identity"
+               arr id = identity
hunk ./Control/Arrow.hs 120
-       f >>> g = g . f
hunk ./Control/Arrow.hs 130
+instance Monad m => Compositor (Kleisli m) where
+       identity = Kleisli return
+       Kleisli f >>> Kleisli g = Kleisli (\b -> f b >>= g)
+
hunk ./Control/Arrow.hs 136
-       Kleisli f >>> Kleisli g = Kleisli (\b -> f b >>= g)
hunk ./Control/Arrow.hs 152
--- | Right-to-left composition, for a better fit with arrow notation.
-(<<<) :: Arrow a => a c d -> a b c -> a b d
-f <<< g = g >>> f
-
hunk ./Control/Compositor.hs 1
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Compositor
+-- Copyright   :  (c) Ashley Yakeley 2007
+-- License     :  BSD-style (see the LICENSE file in the distribution)
+--
+-- Maintainer  :  ashley@semantic.org
+-- Stability   :  experimental
+-- Portability :  portable
+
+module Control.Compositor where
+
+infixr 1 >>>, <<<
+
+class Compositor comp where
+       identity :: comp a a
+
+       -- | Left-to-right composition
+       (>>>) :: comp a b -> comp b c -> comp a c
+
+{-# RULES
+"identity/left"        forall p .
+               identity >>> p = p
+"identity/right"       forall p .
+               p >>> identity = p
+"association"  forall p q r .
+               (p >>> q) >>> r = p >>> (q >>> r)
+ #-}
+
+instance Compositor (->) where
+       identity = id
+       p >>> q = q . p
+
+-- | Right-to-left composition
+(<<<) :: Compositor comp => comp b c -> comp a b -> comp a c
+f <<< g = g >>> f
+
hunk ./base.cabal 69
+        Control.Compositor,
}

Context:

[expose the value of +RTS -N as GHC.Conc.numCapabilities (see #1733)
Simon Marlow <simonmar@microsoft.com>**20071009132042] 
[typo
Simon Marlow <simonmar@microsoft.com>**20070917130703] 
[put extra-tmp-files field in the right place
Simon Marlow <simonmar@microsoft.com>**20070914140812] 
[Add more entries to boring file
Ian Lynagh <igloo@earth.li>**20070913210500] 
[Add a boring file
Ian Lynagh <igloo@earth.li>**20070913204641] 
[TAG 2007-09-13
Ian Lynagh <igloo@earth.li>**20070913215720] 
Patch bundle hash:
c232026bca8fe5a70b2a70d5963ad2ae55522f4e