Python - Lambdas

Lambdas

Creating a function normally (using def) assigns it to a variable automatically. 
This is different from the creation of other objects - such as strings and integers - which can be created on the fly, without assigning them to a variable. 
The same is possible with functions, provided that they are created using lambda syntax. Functions created this way are known as anonymous.
This approach is most commonly used when passing a simple function as an argument to another function. The syntax is shown in the next example and consists of the lambda keyword followed by a list of arguments, a colon, and the expression to evaluate and return.def my_func(f, arg):
return f(arg)

my_func(lambda x: 2*x*x, 5)
Lambda functions get their name from lambda calculus, which is a model of computation invented by Alonzo Church.

Lambda functions aren't as powerful as named functions. 
They can only do things that require a single expression - usually equivalent to a single line of code.
Example:

#named function
def polynomial(x):
return x**2 + 5*x + 4
print(polynomial(-4))
#lambda
print((lambda x: x**2 + 5*x + 4) (-4))

Lambda functions can be assigned to variables, and used like normal functions.
Example:

double = lambda x: x * 2
print(double(7))

Result:>>>
14
>>>
However, there is rarely a good reason to do this - it is usually better to define a function with def instead.