lambda

[Quinn Dunkan]

On 28 Mar 2000 22:37:53 -0800, Falknor <falknor at worldspy.net> wrote:
>Hmm, what exactly is the use of lambda?  It just isn't clickin for some
>reason....  Are they just syntactical candy (such as the ternary operator ?:
>in C++ is syntactical candy..) or what. *ponders*  Anyone who could explain
>it, and gimme a little example would have my thanx. :)

f = lambda x: x * 2

is the same as

def f(x):
    return x * 2

In other words, lambda is just another way of writing `def' except that it
doesn't have to be named and you can only put an expression in it (return is
implicit).

It's intended to be a shorthand to write small functions easier, but that's
all it is: a shorthand.  This is unlike, say, scheme, where it is the *only*
way to define functions.  Remember, in python, a function is just another
type, like integers and strings and classes.  Classes use Classname() as a
type constructor, strings use ""s, and functions use def and lambda.

It's useful for HOFs (higher-order functions) which want a function as an arg,
like map, filter, and reduce.