Relude.Monad.Trans

Shorter and more readable alias for flip runReader.

>>> usingReader 42 $ asks (+5)47

Shorter and more readable alias for flip runReaderT.

>>> usingReaderT 42 $ asks (+5)47

This function helps with optimizing performance when working with the ReaderT transformer. If you have code like below, that is called in a loop

step :: Instruction -> ReaderT Config IO Result
step instruction = case instruction of
    Add -> do stuff ...
    Del -> do stuff ...

you can improve performance of your Haskell applications by using etaReaderT in the following way:

step :: Instruction -> ReaderT Config IO Result
step instruction = etaReaderT $ case instruction of
    Add -> do stuff ...
    Del -> do stuff ...

For a detailed explanation, refer to the following blog post:

• Faster Winter 5: Eta-Expanding ReaderT (by Joachim Breitner)

Alias for flip evalState. It's not shorter but sometimes more readable. Done by analogy with using* functions family.

Alias for flip evalStateT. It's not shorter but sometimes more readable. Done by analogy with using* functions family.

Alias for flip execState. It's not shorter but sometimes more readable. Done by analogy with using* functions family.

Alias for flip execStateT. It's not shorter but sometimes more readable. Done by analogy with using* functions family.

Shorter and more readable alias for flip runState.

Shorter and more readable alias for flip runStateT.

>>> usingStateT 0 $ put 42 >> pure False(False,42)

Lift a Maybe to the MaybeT monad

Lift a Either to the ExceptT monad