Understanding the 'lambda' Keyword in Python

The 'lambda' keyword in Python is used to create something known as an 'anonymous function', or a function without a name. This stands in stark contrast to the normal Python function which is defined using the 'def' keyword. 'Lambda' functions are often useful when we want to perform some small operation without the need for an explicit function.

Explaining Anonymous Functions in Python

Anonymous functions refer to functions that are defined without a name. While normal functions are defined using the keyword 'def', in Python, anonymous functions are defined using the keyword 'lambda'.

Here's an example:

sum = lambda a, b: a + b
print(sum(3, 4))  # Output: 7

This piece of code describes a function which takes in two arguments (a and b), and returns their sum.

The primary difference between lambda functions and normal Python functions is that lambda functions are usually shorter and easier to read when used with functions like map(), filter(), and reduce() to operate on lists.

For instance, if you wanted to square all the elements in a list, you would use map() with a lambda function as follows:

list_ = [1, 2, 3, 4, 5]
square_list = map(lambda x: x**2, list_)
print(list(square_list))  # Output: [1, 4, 9, 16, 25]

Best Practices and Additional Insights

While the use of 'lambda' functions can make your code more readable and concise, it's essential to understand when and where it's appropriate to use them.

1. Function Simplicity: Lambda functions are best used when you're dealing with simple functions. If the operation becomes too complicated, using a def-defined function is preferable for the sake of clarity and readability.

2. Single Time Use: If a function is only used once, or a limited number of times, an inline lambda function can be used. If a function is going to be used repeatedly, it is best to define it normally for easier testing and debugging.

Consider 'lambda' as a tool in your toolkit, to be used when it can make your life - or that of anyone else who will be reading your code - a little bit simpler.