monoid-transformer (empty) → 0.0.1

raw patch · 6 files changed

+123/−0 lines, 6 filesdep +basesetup-changed

Dependencies added: base

Files

• LICENSE +31/−0
• Setup.lhs +3/−0
• monoid-transformer.cabal +37/−0
• src/Data/Monoid/Reader.hs +15/−0
• src/Data/Monoid/State.hs +31/−0
• src/Data/Monoid/Transformer.hs +6/−0

@@ -0,0 +1,31 @@+Copyright (c) 2009, Henning Thielemann++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.++    * The names of contributors may not 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.

@@ -0,0 +1,3 @@+#! /usr/bin/env runhaskell+> import Distribution.Simple+> main = defaultMain

@@ -0,0 +1,37 @@+Name:             monoid-transformer+Version:          0.0.1+License:          BSD3+License-File:     LICENSE+Author:           Henning Thielemann <haskell@henning-thielemann.de>+Maintainer:       Henning Thielemann <haskell@henning-thielemann.de>+-- Homepage:         http://www.haskell.org/haskellwiki/Monoid transformer+Category:         Data+Synopsis:         Monoid counterparts to some ubiquitous monad transformers+-- Portability:      Haskell 98+Description:+  Monoid transformers: State, Reader+  There is no Writer transformer.+  It's vice versa: The Writer monad transforms a monoid to a monad.+Tested-With:       GHC==6.8.2+Cabal-Version:     >=1.6+Build-Type:        Simple++Source-Repository head+  type:     darcs+  location: http://code.haskell.org/~thielema/monoid/++Source-Repository this+  type:     darcs+  location: http://code.haskell.org/~thielema/monoid/+  tag:      0.0.1+++Library+  Build-Depends: base++  GHC-Options:      -Wall+  Hs-Source-Dirs:   src+  Exposed-Modules:+    Data.Monoid.Reader+    Data.Monoid.State+    Data.Monoid.Transformer

@@ -0,0 +1,15 @@+module Data.Monoid.Reader where++import qualified Data.Monoid.Transformer as MonoidTrans+import Data.Monoid (Monoid, mempty, mappend, )+++newtype T r a = Cons {run :: r -> a}++instance Monoid a => Monoid (T r a) where+   mempty = MonoidTrans.lift mempty+   mappend (Cons x) (Cons y) =+      Cons $ \r -> mappend (x r) (y r)++instance MonoidTrans.C (T r) where+   lift = Cons . const

@@ -0,0 +1,31 @@+module Data.Monoid.State where++import qualified Data.Monoid.Transformer as MonoidTrans+import Data.Monoid (Monoid, mempty, mappend, )++newtype T s a = Cons {run :: s -> (a,s)}++evaluate :: s -> T s a -> a+evaluate s m = fst $ run m s++execute :: s -> T s a -> s+execute s m = snd $ run m s+++put :: Monoid a => s -> T s a+put s = Cons $ const (mempty, s)++modify :: Monoid a => (s -> s) -> T s a+modify f = Cons $ \s -> (mempty, f s)+++instance Monoid a => Monoid (T s a) where+   mempty = MonoidTrans.lift mempty+   mappend (Cons x) (Cons y) =+      Cons $ \s0 ->+         let (xr,s1) = x s0+             (yr,s2) = y s1+         in  (mappend xr yr, s2)++instance MonoidTrans.C (T r) where+   lift x = Cons $ (,) x

@@ -0,0 +1,6 @@+module Data.Monoid.Transformer where++import Data.Monoid (Monoid, )++class C t where+   lift :: (Monoid m) => m -> t m