recursion-schemes 0.2 → 0.2.1

raw patch · 2 files changed

+17/−1 lines, 2 files

Files

• Data/Functor/Foldable.hs +12/−0
• recursion-schemes.cabal +5/−1

@@ -54,6 +54,9 @@   -- * Mendler-style   , mcata   , mhisto+  -- * Elgot (co)algebras+  , elgot+  , coelgot   ) where  import Control.Applicative@@ -62,6 +65,7 @@ import Control.Comonad.Trans.Env import Control.Monad (liftM, join) import Data.Functor.Identity+import Control.Arrow import Data.Function (on) import qualified Data.Stream.Branching as Stream import Data.Stream.Branching (Stream(..))@@ -354,3 +358,11 @@ -- | Mendler-style course-of-value iteration mhisto :: (forall y. (y -> c) -> (y -> f y) -> f y -> c) -> Fix f -> c mhisto psi = psi (mhisto psi) unfix . unfix++-- | Elgot algebras+elgot :: Functor f => (f a -> a) -> (b -> Either a (f b)) -> b -> a+elgot phi psi = h where h = (id ||| phi . fmap h) . psi++-- | Elgot coalgebras: <http://comonad.com/reader/2008/elgot-coalgebras/>+coelgot :: Functor f => ((a, f b) -> b) -> (a -> f a) -> a -> b+coelgot phi psi = h where h = phi . (id &&& fmap h . psi)

@@ -1,6 +1,6 @@ name:          recursion-schemes category:      Control, Recursion-version:       0.2+version:       0.2.1 license:       BSD3 cabal-version: >= 1.6 license-file:  LICENSE@@ -13,6 +13,10 @@ description:      Generalized bananas, lenses and barbed wire   . +  /Changes since 0.2/:+  .+  * Added Elgot (co)algebras+  .   /Changes since 0.1/:   .   * Removed dependency on Foldable from Mendler-style recursion schemes