Control.Monad.Trans

mtl-2.0.1.0: Monad classes, using functional dependencies

Portability | portable
Stability | experimental
Maintainer | libraries@haskell.org

Control.Monad.Trans

Description

Classes for monad transformers.

A monad transformer makes new monad out of an existing monad, such that computations of the old monad may be embedded in the new one. To construct a monad with a desired set of features, one typically starts with a base monad, such as `Identity`, `[]` or `IO`, and applies a sequence of monad transformers.

Most monad transformer modules include the special case of applying the transformer to `Identity`. For example, `State s` is an abbreviation for `StateT s Identity`.

Each monad transformer also comes with an operation `run`XXX to unwrap the transformer, exposing a computation of the inner monad.

# Documentation

module Control.Monad.Trans.Class

module Control.Monad.IO.Class