In functional programming, a function is considered pure if it has no side effects. That is, given the same inputs, the function will always return the same output and won't modify any global state. Pure functions are often used to improve code clarity and make programs easier to reason about.
There are several benefits of using pure functions. First, they are much easier to test since you can be confident that they will always return the same results given the same inputs. This makes it simpler to find and fix bugs in your code.
Second, pure functions can be memoized, which means that they can be cached so that subsequent calls with the same input values don't have to recalculate the output. This can lead to significant performance gains in programs that make heavy use of pure functions.
Finally, pure functions make it easier to parallelize code since there is no need to worry about race conditions or other side effects when multiple threads are executing different parts of the program concurrently.
Overall, using pure functions can help you write cleaner and more efficient code. However, there are some trade-offs to consider as well. For example,pure functions can sometimes be less expressive than impure ones (since you're restricted by not being able to modify global state). Additionally, if memoization isn't used carefully it can lead to memory leaks since old values may never get garbage collected