From the course: Functional Programming with Java

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Functional purity

Functional purity - Java Tutorial

From the course: Functional Programming with Java

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Functional purity

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- [Narrator] The second main concept of functional programming is something called functional purity. In functional programming, we aim to make all of our functions into pure functions. And what this means is that the functions we write should always return the same output, given the same arguments. And if this doesn't quite make sense to you yet, let's take a look at what functions that are not pure look like. Basically functions are not pure whenever they refer to some sort of internal or external state that changes. Now probably the most common example of this in Java is when you have methods in a class they're referred to a mutable member variable, let's say that we have a person class with a private age member variable, and then we have a method called get age, which simply returns the value of this age variable. This get age function is probably not pure and here's why. We can call it once and it might return some number like 34, basically whatever the person's age is at that…

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