adjunctions (empty) → 0.1

raw patch · 5 files changed

+152/−0 lines, 5 filesdep +basedep +transformerssetup-changed

Dependencies added: base, transformers

Files

• Control/Monad/Trans/Adjoint.hs +53/−0
• Data/Functor/Adjunction.hs +33/−0
• LICENSE +30/−0
• Setup.lhs +7/−0
• adjunctions.cabal +29/−0

@@ -0,0 +1,53 @@+{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-}+-----------------------------------------------------------------------------+-- |+-- Module      :  Control.Monad.Trans.Adjoint+-- Copyright   :  (C) 2011 Edward Kmett+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  Edward Kmett <ekmett@gmail.com>+-- Stability   :  provisional+-- Portability :  MPTCs, fundeps+--+----------------------------------------------------------------------------++module Control.Monad.Trans.Adjoint+  ( Adjoint+  , runAdjoint+  , adjoint+  , AdjointT(..)+  ) where++import Prelude hiding (sequence)+import Control.Applicative+import Control.Monad (ap, liftM)+import Control.Monad.Trans.Class+import Data.Traversable+import Data.Functor.Adjunction+import Data.Functor.Identity++type Adjoint f g = AdjointT f g Identity++newtype AdjointT f g m a = AdjointT { runAdjointT :: g (m (f a)) }++adjoint :: Functor g => g (f a) -> Adjoint f g a+adjoint = AdjointT . fmap Identity++runAdjoint :: Functor g => Adjoint f g a -> g (f a)+runAdjoint = fmap runIdentity . runAdjointT++instance (Adjunction f g, Monad m) => Functor (AdjointT f g m) where+  fmap f (AdjointT g) = AdjointT $ fmap (liftM (fmap f)) g+  b <$ (AdjointT g) = AdjointT $ fmap (liftM (b <$)) g+  +instance (Adjunction f g, Monad m) => Applicative (AdjointT f g m) where+  pure = AdjointT . leftAdjunct return+  (<*>) = ap++instance (Adjunction f g, Monad m) => Monad (AdjointT f g m) where+  return = AdjointT . leftAdjunct return+  AdjointT m >>= f = AdjointT $ fmap (>>= rightAdjunct (runAdjointT . f)) m+    +-- | Exploiting this instance requires that we have the missing Traversables for Identity, (,)e and IdentityT+instance (Adjunction f g, Traversable f) => MonadTrans (AdjointT f g) where+  lift = AdjointT . fmap sequence . unit

@@ -0,0 +1,33 @@+{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, UndecidableInstances #-}+module Data.Functor.Adjunction +  ( Adjunction(..)+  ) where++import Control.Monad.Instances ()+import Control.Monad.Trans.Identity+import Data.Functor.Identity++-- > rightAdjunct unit = id+-- > leftAdjunct counit = id +class (Functor f, Functor g) => Adjunction f g | f -> g, g -> f where+  unit :: a -> g (f a)+  counit :: f (g a) -> a+  leftAdjunct :: (f a -> b) -> a -> g b+  rightAdjunct :: (a -> g b) -> f a -> b+  +  unit = leftAdjunct id+  counit = rightAdjunct id+  leftAdjunct f = fmap f . unit+  rightAdjunct f = counit . fmap f++instance Adjunction ((,)e) ((->)e) where+  leftAdjunct f a e = f (e, a)+  rightAdjunct f ~(e, a) = f a e++instance Adjunction Identity Identity where+  leftAdjunct f = Identity . f . Identity+  rightAdjunct f = runIdentity . f . runIdentity++instance Adjunction f g => Adjunction (IdentityT f) (IdentityT g) where+  unit = IdentityT . fmap IdentityT . unit+  counit = counit . fmap runIdentityT . runIdentityT

@@ -0,0 +1,30 @@+Copyright 2011 Edward Kmett++All rights reserved.++Redistribution and use in source and binary forms, with or without+modification, are permitted provided that the following conditions+are met:++1. Redistributions of source code must retain the above copyright+   notice, this list of conditions and the following disclaimer.++2. 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.++3. Neither the name of the author nor the names of his contributors+   may be used to endorse or promote products derived from this software+   without specific prior written permission.++THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.

@@ -0,0 +1,7 @@+#!/usr/bin/runhaskell+> module Main (main) where++> import Distribution.Simple++> main :: IO ()+> main = defaultMain

@@ -0,0 +1,29 @@+name:          adjunctions+category:      Data Structures, Adjunctions+version:       0.1+license:       BSD3+cabal-version: >= 1.6+license-file:  LICENSE+author:        Edward A. Kmett+maintainer:    Edward A. Kmett <ekmett@gmail.com>+stability:     provisional+homepage:      http://github.com/ekmett/adjunctions/+copyright:     Copyright (C) 2011 Edward A. Kmett+synopsis:      Adjunctions+description:   Adjunctions+build-type:    Simple++source-repository head+  type: git+  location: git://github.com/ekmett/adjunctions.git++library+  build-depends: +    base >= 4 && < 4.4,+    transformers >= 0.2.0 && < 0.3++  exposed-modules:+    Control.Monad.Trans.Adjoint+    Data.Functor.Adjunction++  ghc-options: -Wall