Editing Monad (functional programming) (section)

=== Identity monad ===
The simplest monad is the '''Identity monad''', which just annotates plain values and functions to satisfy the monad laws:
 '''newtype''' Id T  =  T
 
 unit(x)    =  x
 (x >>= f)  =  f(x)

<code>Identity</code> does actually have valid uses though, such as providing a [[base case (recursion)|base case]] for recursive [[monad transformer]]s.
It can also be used to perform basic variable assignment within an imperative-style block.{{efn|In category theory, the <code>Identity</code> monad can also be viewed as emerging from [[adjunction (category theory)|adjunction]] of any functor with its inverse.}}{{citation needed|date=October 2018}}