contravariant 0.1.0.1 → 0.1.1

raw patch · 2 files changed

+20/−3 lines, 2 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• Data/Functor/Contravariant.hs +19/−2
• contravariant.cabal +1/−1

@@ -27,6 +27,9 @@   -- * Equivalence Relations   , Equivalence(..)   , defaultEquivalence+  +  -- * Dual arrows+  , Op(..)   ) where  -- | Any instance should be subject to the following laws:@@ -35,18 +38,22 @@ -- > contramap f . contramap g = contramap (g . f) -- -- Note, that the second law follows from the free theorem of the type of --- 'contramap' and the first law, so you--- need only check that the former condition holds.+-- 'contramap' and the first law, so you need only check that the former +-- condition holds.  class Contravariant f where   contramap :: (a -> b) -> f b -> f a  ++ newtype Predicate a = Predicate { getPredicate :: a -> Bool }  -- | A 'Predicate' is a 'Contravariant' 'Functor', because 'contramap' can  -- apply its function argument to the input of the predicate. instance Contravariant Predicate where   contramap f g = Predicate $ getPredicate g . f ++ -- | Defines a total ordering on a type as per 'compare' newtype Comparison a = Comparison { getComparison :: a -> a -> Ordering }  @@ -60,6 +67,8 @@ defaultComparison :: Ord a => Comparison a defaultComparison = Comparison compare ++ -- | Define an equivalence relation  newtype Equivalence a = Equivalence { getEquivalence :: a -> a -> Bool }  -- | Equivalence relations are 'Contravariant', because you can @@ -71,3 +80,11 @@ -- | Check for equivalence with '==' defaultEquivalence :: Eq a => Equivalence a defaultEquivalence = Equivalence (==)++++-- | Dual function arrows.+newtype Op a b = Op { getOp :: b -> a } ++instance Contravariant (Op a) where+  contramap f g = Op (getOp g . f)

@@ -1,6 +1,6 @@ name:          contravariant category:      Control, Data-version:       0.1.0.1+version:       0.1.1 license:       BSD3 cabal-version: >= 1.6 license-file:  LICENSE