Defining point of functional programming

Question

I can enumerate many features of functional programming, but when my friend asked me Could you define functional programming for me? I couldn\'t.

Answer 1

There are two separate definitions:

• The older definition (first-class functions) has been given by Chris Conway.

• The newer definition (avoiding side effects like mutation) has been given by John Stauffer. This is more generally known as purely functional programming.

This is a source of much confusion...