reader package:dunai

Constructor for computations in the reader monad (equivalent to asks).

Constructor for computations in the reader monad (equivalent to asks).

MSFs with a Reader monadic layer. This module contains functions to work with MSFs that include a Reader monadic layer. This includes functions to create new MSFs that include an additional layer, and functions to flatten that layer out of the MSF's transformer stack.

The parameterizable reader monad. Computations are functions of a shared environment. The return function ignores the environment, while >>= passes the inherited environment to both subcomputations.

Build an MSF in the Reader monad from one that takes the reader environment as an extra input. This is the opposite of runReaderS.

The reader monad transformer, which adds a read-only environment to the given monad. The return function ignores the environment, while >>= passes the inherited environment to both subcomputations.

Transform the value returned by a Reader.

• runReader (mapReader f m) = f .
  runReader m

Transform the computation inside a ReaderT.

• runReaderT (mapReaderT f m) = f .
  runReaderT m

Runs a Reader and extracts the final value from it. (The inverse of reader.)

Build an MSF that takes an environment as an extra input from one on the Reader monad. This is the opposite of readerS.

Build an MSF function that takes a fixed environment as additional input, from an MSF in the Reader monad.

Execute a computation in a modified environment (a specialization of withReaderT).

• runReader (withReader f m) = runReader m
  . f

Execute a computation in a modified environment (a more general version of local).

• runReaderT (withReaderT f m) =
  runReaderT m . f