Control.Monad.Freer.Reader

Composable handler for Reader effects. Handy for encapsulating an environment with immutable state for interpreters.

Using http://okmij.org/ftp/Haskell/extensible/Eff1.hs as a starting point.

Documentation

data Reader e v where

Constructors

Reader :: Reader e e

ask :: Member (Reader e) r => Eff r e

Request a value for the environment

runReader :: Eff (Reader e : r) w -> e -> Eff r w

Handler for reader effects

local :: forall e a r. Member (Reader e) r => (e -> e) -> Eff r a -> Eff r a

Locally rebind the value in the dynamic environment This function is like a relay; it is both an admin for Reader requests, and a requestor of them