Portability	non-portable (fundeps, MPTCs)
Stability	experimental
Maintainer	Edward Kmett <ekmett@gmail.com>
Safe Haskell	Trustworthy

Control.Comonad.Env

Contents

Description

The Env comonad (aka the Coreader, Environment, or Product comonad)

A co-Kleisli arrow in the Env comonad is isomorphic to a Kleisli arrow in the reader monad.

(a -> e -> m) ~ (a, e) -> m ~ Env e a -> m

Synopsis

ComonadEnv class

class Comonad w => ComonadEnv e w | w -> e whereSource

Methods

ask :: w a -> eSource

Instances

ComonadEnv e w => ComonadEnv e (IdentityT w)
ComonadEnv e ((,) e)
(ComonadEnv e w, Monoid m) => ComonadEnv e (TracedT m w)
ComonadEnv e w => ComonadEnv e (StoreT t w)
Comonad w => ComonadEnv e (EnvT e w)

asks :: ComonadEnv e w => (e -> e') -> w a -> e'Source

local :: (e -> e') -> EnvT e w a -> EnvT e' w aSource

Modifies the environment using the specified function.

The Env comonad

type Env e = EnvT e IdentitySource

env :: e -> a -> Env e aSource

Create an Env using an environment and a value

runEnv :: Env e a -> (e, a)Source

data EnvT e w a Source

Constructors

EnvT e (w a)

Instances

Comonad w => ComonadEnv e (EnvT e w)
ComonadStore s w => ComonadStore s (EnvT e w)
ComonadTraced m w => ComonadTraced m (EnvT e w)
ComonadTrans (EnvT e)
ComonadHoist (EnvT e)
Functor w => Functor (EnvT e w)
(Typeable s, Typeable1 w) => Typeable1 (EnvT s w)
Foldable w => Foldable (EnvT e w)
Traversable w => Traversable (EnvT e w)
(Semigroup e, ComonadApply w) => ComonadApply (EnvT e w)
Comonad w => Comonad (EnvT e w)
(Data e, Typeable1 w, Data (w a), Data a) => Data (EnvT e w a)
(Typeable s, Typeable1 w, Typeable a) => Typeable (EnvT s w a)

runEnvT :: EnvT e w a -> (e, w a)Source