Cleff.Reader

Effect

data Reader r :: Effect where

An effect capable of providing an immutable environment r that can be read. This roughly corresponds to the MonadReader typeclass and ReaderT monad transformer in the mtl library.

Constructors

Ask :: Reader r m r

Local :: (r -> r) -> m a -> Reader r m a

Operations

ask :: Reader r :> es => Eff es r

Obtain the environment value.

local

Arguments

:: Reader r :> es

=> (r -> r)

The function that modifies the environment

-> Eff es a

The computation to run with the modified environment

-> Eff es a

Modify the environment value temporarily for a computation.

asks :: Reader r :> es => (r -> s) -> Eff es s

Apply a function to the result of ask.

Interpretations

runReader :: r -> Eff (Reader r ': es) ~> Eff es

Run a Reader effect with a given environment value.

magnify :: Reader t :> es => Lens' t r -> Eff (Reader r ': es) ~> Eff es

Run a Reader effect in terms of a larger Reader via a Lens'.