What is Functional Programming? - Adam Warski | Lambda Days

[CodeSync]

What is Functional Programming? - Adam Warski | Lambda Days 2025

What is Functional Programming? - Adam Warski | Lambda Days 2025

This talk was recorded at Lambda Days in June 2025. If you’re curious about our upcoming event, check https://lambdadays.org

What is Functional Programming?
Functional programming is here to stay. While it hasn’t taken over the world, many of today’s popular programming languages have at least borrowed some of its concepts.

But if someone asks you, “What is functional programming?”—would you be able to answer? Specifically, when can we call a language “functional”? Or, what exactly is “functional style”?

In this talk, we’ll explore the features that may define a language as functional, first by trying to visually identify “functional” code, and then trying to generalise our intuition. This covers topics all the way from higher-order functions, to capturing effects as values.

Next, we’ll introduce a couple of FP flavours, which might help to understand, why the definitions of FP that circulate in the virtual world sometimes seem so different.

Finally, we’ll try to judge which FP features bring the most value, and quantify a couple of mainstream languages in their “functionfullness”.

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