← Glossary
What does "pure function" mean in programming?
pure function is one of the most common terms in software development. This guide explains what it means, how it is used in practice, and why it matters, with real examples from the developer world.
Definition
A function that always returns the same output for the same input and has no side effects: it does not modify external state, write to a database, or call an API. Pure functions are predictable, easy to test, and safe to run in parallel.
Example
"calculateTax(price, rate) is a pure function — give it the same inputs and it always returns the same result."
Related terms
Ready to practice your English at work?
Lingua-e has interactive exercises built around real developer conversations: standups, code reviews, retrospectives, and more. Practice until it comes naturally.
Try Lingua-e for free