The identity functor and monad.
This trivial type constructor serves two purposes:
- It can be used with functions parameterized by functor or monad classes.
- It can be used as a base monad to which a series of monad
transformers may be applied to construct a composite monad.
Most monad transformer modules include the special case of
applying the transformer to
Identity. For example,
State sis an abbreviation for
Identity functor and monad. (a non-strict monad)