invariant (empty) → 0.1.0

raw patch · 4 files changed

+169/−0 lines, 4 filesdep +basedep +contravariantsetup-changed

Dependencies added: base, contravariant

Files

• Data/Functor/Invariant.hs +122/−0
• LICENSE +23/−0
• Setup.hs +2/−0
• invariant.cabal +22/−0

@@ -0,0 +1,122 @@+module Data.Functor.Invariant (Invariant(..), Invariant2(..)) where++import Text.ParserCombinators.ReadP (ReadP)+import Text.ParserCombinators.ReadPrec (ReadPrec)++import qualified Control.Category as Cat+import Control.Arrow (Arrow(..))+import Control.Applicative (Const(Const), ZipList)+import Control.Applicative (WrappedMonad, WrappedArrow(WrapArrow))++import Control.Monad.ST (ST)++import Data.Functor.Contravariant+import Data.Functor.Contravariant.Compose++++++-- | Any @*->*@ type parametric in the argument permits an instance of+-- @Invariant@.+--+-- Instances should satisfy the following laws:+--+-- > invmap id id = id+-- > invmap f2 f2' . invmap f1 f1' = invmap (f2 . f1) (f1' . f2')+class Invariant f where+  invmap :: (a -> b) -> (b -> a) -> f a -> f b++++++-- | Any @*->*->*@ type parametric in both arguments permits an instance of+-- @Invariant2@.+--+-- Instances should satisfy the following laws:+--+-- > invmap2 id id id id = id+-- > invmap2 f2 f2' g2 g2' . invmap2 f1 f1' g1 g1' =+-- >   invmap2 (f2 . f1) (f1' . f2') (g2 . g1) (g1' . g2')+class Invariant2 f where+  invmap2 :: (a -> c) -> (c -> a) -> (b -> d) -> (d -> b) -> f a b -> f c d++++++instance Invariant Maybe where invmap = flip $ const fmap+instance Invariant [] where invmap = flip $ const fmap+instance Invariant IO where invmap = flip $ const fmap+instance Invariant (ST s) where invmap = flip $ const fmap+instance Invariant ReadP where invmap = flip $ const fmap+instance Invariant ReadPrec where invmap = flip $ const fmap+instance Invariant ((->) a) where invmap = flip $ const fmap+instance Invariant (Either a) where invmap = flip $ const fmap+instance Invariant ((,) a) where invmap = flip $ const fmap+instance Invariant ((,,) a b) where invmap f _ ~(a, b, x) = (a, b, f x)+instance Invariant ((,,,) a b c) where+  invmap f _ ~(a, b, c, x) = (a, b, c, f x)+instance Invariant ((,,,,) a b c d) where+  invmap f _ ~(a, b, c, d, x) = (a, b, c, d, f x)++instance Invariant2 (->) where invmap2 _ f' g _ = (g .) . (. f')+instance Invariant2 Either where+  invmap2 f _ _ _ (Left  x) = Left  $ f x+  invmap2 _ _ g _ (Right y) = Right $ g y+instance Invariant2 (,) where invmap2 f _ g _ ~(x, y) = (f x, g y)+instance Invariant2 ((,,) a) where invmap2 f _ g _ ~(a, x, y) = (a, f x, g y)+instance Invariant2 ((,,,) a b) where+  invmap2 f _ g _ ~(a, b, x, y) = (a, b, f x, g y)+instance Invariant2 ((,,,,) a b c) where+  invmap2 f _ g _ ~(a, b, c, x, y) = (a, b, c, f x, g y)++++++-- | @Control.Applicative@+instance Invariant (Const a) where invmap _ _ (Const x) = Const x+-- | @Control.Applicative@+instance Invariant ZipList where invmap = flip $ const fmap+-- | @Control.Applicative@+instance Monad m => Invariant (WrappedMonad m) where invmap = flip $ const fmap+-- | @Control.Applicative@+instance Arrow arr => Invariant (WrappedArrow arr a) where+  invmap f _ (WrapArrow x) = WrapArrow $ ((arr f) Cat.. x)+-- | @Control.Applicative@+instance Invariant2 Const where invmap2 f _ _ _ (Const x) = Const (f x)+-- | @Control.Applicative@+instance Arrow arr => Invariant2 (WrappedArrow arr) where+  invmap2 _ f' g _ (WrapArrow x) = WrapArrow $ arr g Cat.. x Cat.. arr f'++++++-- | from the @contravariant@ package+instance Invariant Predicate where invmap = const contramap+-- | from the @contravariant@ package+instance Invariant Comparison where invmap = const contramap+-- | from the @contravariant@ package+instance Invariant Equivalence where invmap = const contramap+-- | from the @contravariant@ package+instance Invariant (Op a) where invmap = const contramap+-- | from the @contravariant@ package+instance Invariant2 Op where+  invmap2 f f' g g' (Op x) = Op $ invmap2 g g' f f' x++++++-- | from the @contravariant@ package+instance (Invariant f, Invariant g) => Invariant (Compose f g) where+  invmap f g (Compose x) = Compose $ invmap (invmap f g) (invmap g f) x+-- | from the @contravariant@ package+instance (Invariant f, Invariant g) => Invariant (ComposeCF f g) where+  invmap f g (ComposeCF x) = ComposeCF $ invmap (invmap f g) (invmap g f) x+-- | from the @contravariant@ package+instance (Invariant f, Invariant g) => Invariant (ComposeFC f g) where+  invmap f g (ComposeFC x) = ComposeFC $ invmap (invmap f g) (invmap g f) x

@@ -0,0 +1,23 @@+Copyright (c) 2012, University of Kansas+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.++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 HOLDER 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 +1,2 @@+import Distribution.Simple+main = defaultMain

@@ -0,0 +1,22 @@+name: invariant+version: 0.1.0+synopsis: Haskell 98 invariant functors+description: Haskell 98 invariant functors++category: Control, Data++license: BSD3+license-file: LICENSE+author: Nicolas Frisby <nicolas.frisby@gmail.com>+maintainer: Nicolas Frisby <nicolas.frisby@gmail.com>++build-type: Simple+cabal-version: >= 1.6++++library+  build-depends: base >= 4 && < 5+  build-depends: contravariant >= 0.1.2 && < 0.3++  exposed-modules: Data.Functor.Invariant