Mention "anonymous functions" and you just might bewilder a mathematician but a programmer will simply nod with understanding.
It turns out the concept itself is not unfamiliar to mathematicians, it's just they never bothered to christen the concept: anonymous functions are functions that are not bound to a name. (Can you say "Duh"?)
The function $f(x) = 2x$ is not anonymous, its name is $f(x)$; its anonymous version is $y = 2x$.
In Python a function is defined like so:
[python]
def f(x):
return 2*x
[/python]
Anonymous functions are defined using the construct $lambda$:
[python]
g = lambda x : 2*x
[/python]
And, oh, the irony, I assigned the name $g$ to the anonymous function!

Anonymous Functions