Anonymous function

In computer science and mathematics, an anonymous function is a function that has no name. Usually, a function is written like: $f(x)=x^{2}-x+42$. It can be written anonymously as $x\rightarrow x^{2}-x+42$ These are used in functional programming languages and other programming languages with support for anonymous functions (those which support 1st class functions).

Example in Python

(lambda x: (lambda y: x * y))

The above code can be executed as a function:

>>>(lambda x: (lambda y: x * y))(3)(4)
12