| Copyright | (C) 2008-2013 Edward Kmett |
|---|---|
| License | BSD-style (see the file LICENSE) |
| Maintainer | Edward Kmett <ekmett@gmail.com> |
| Stability | provisional |
| Portability | MPTCs, fundeps |
| Safe Haskell | Safe-Inferred |
| Language | Haskell2010 |
Control.Comonad.Trans.Coiter
Contents
Description
The coiterative comonad generated by a comonad
- newtype CoiterT w a = CoiterT {
- runCoiterT :: w (a, CoiterT w a)
- type Coiter = CoiterT Identity
- coiter :: a -> Coiter a -> Coiter a
- runCoiter :: Coiter a -> (a, Coiter a)
- unfold :: Comonad w => (w a -> a) -> w a -> CoiterT w a
- class (Functor f, Comonad w) => ComonadCofree f w | w -> f where
- unwrap :: w a -> f (w a)
Documentation
Coiterative comonads represent non-terminating, productive computations.
They are the dual notion of iterative monads. While iterative computations produce no values or eventually terminate with one, coiterative computations constantly produce values and they never terminate.
It's simpler form, Coiter, is an infinite stream of data. CoiterT
extends this so that each step of the computation can be performed in
a comonadic context.
The coiterative comonad transformer
This is the coiterative comonad generated by a comonad
Constructors
| CoiterT | |
Fields
| |
Instances
| ComonadHoist CoiterT | |
| ComonadTrans CoiterT | |
| ComonadTraced m w => ComonadTraced m (CoiterT w) | |
| ComonadStore s w => ComonadStore s (CoiterT w) | |
| ComonadEnv e w => ComonadEnv e (CoiterT w) | |
| Comonad w => ComonadCofree Identity (CoiterT w) | |
| Functor w => Functor (CoiterT w) | |
| Foldable w => Foldable (CoiterT w) | |
| Traversable w => Traversable (CoiterT w) | |
| Comonad w => Comonad (CoiterT w) | |
| (Functor w, Eq1 w) => Eq1 (CoiterT w) | |
| (Functor w, Ord1 w) => Ord1 (CoiterT w) | |
| (Functor w, Show1 w) => Show1 (CoiterT w) | |
| (Functor w, Read1 w) => Read1 (CoiterT w) | |
| Eq (w (a, CoiterT w a)) => Eq (CoiterT w a) | |
| (Typeable (* -> *) w, Typeable * a, Data (w (a, CoiterT w a)), Data a) => Data (CoiterT w a) | |
| Ord (w (a, CoiterT w a)) => Ord (CoiterT w a) | |
| Read (w (a, CoiterT w a)) => Read (CoiterT w a) | |
| Show (w (a, CoiterT w a)) => Show (CoiterT w a) | |
| Typeable ((* -> *) -> * -> *) CoiterT |
The coiterative comonad
coiter :: a -> Coiter a -> Coiter a Source
Prepends a result to a coiterative computation.
runCoiter . uncurry coiter == id
runCoiter :: Coiter a -> (a, Coiter a) Source
Extracts the first result from a coiterative computation.
uncurry coiter . runCoiter == id
Generating coiterative comonads
unfold :: Comonad w => (w a -> a) -> w a -> CoiterT w a Source
Unfold a CoiterT comonad transformer from a cokleisli arrow and an initial comonadic seed.
Cofree comonads
class (Functor f, Comonad w) => ComonadCofree f w | w -> f where Source
Allows you to peel a layer off a cofree comonad.
Instances
| ComonadCofree Maybe NonEmpty | |
| ComonadCofree f w => ComonadCofree f (IdentityT w) | |
| Functor f => ComonadCofree f (Cofree f) | |
| Comonad w => ComonadCofree Identity (CoiterT w) | |
| (ComonadCofree f w, Semigroup m, Monoid m) => ComonadCofree f (TracedT m w) | |
| ComonadCofree f w => ComonadCofree f (StoreT s w) | |
| ComonadCofree f w => ComonadCofree f (EnvT e w) | |
| (Functor f, Comonad w) => ComonadCofree f (CofreeT f w) | |
| ComonadCofree (Const b) ((,) b) |