What are pure and impure functions in programming?

Can you explain the difference between pure and impure functions?

Sure! A pure function always produces the same output for the same input and has no side effects. An impure function, on the other hand, may produce different outputs for the same inputs or have side effects.

Can you give me an example of a pure function?

Absolutely! A simple example of a pure function is a function that adds two numbers together, like add(a, b) { return a + b; }. It always returns the same result for the same inputs.

What about an example of an impure function?

An example of an impure function is one that modifies a global variable or relies on external data, like getRandomNumber() { return Math.random(); }. Its output can change every time it's called.

Why are pure functions preferred in programming?

Pure functions are preferred because they are easier to test, debug, and reason about. They also enable better optimization by compilers.