PurelyFunctional.tv Newsletter 263: The Power of Definitions

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Issue 263 - February 05, 2018 · Archives · Subscribe

Hi Functional Programmers,

I've been thinking a lot about what Functional Programming is. I've given a few talks now to develop a new definition of it. If you search on the web for "what is functional programming?", you don't get much that is useful. I'd like to change that and create a definition that can help us discuss what we do with others.

Go now and do a search. You'll see examples of "definitions" like "programming without side-effects" and "programming without mutable state". However, in every last program I've ever written, functional or not, I've had side-effects and I've used mutable state. These definitions do more harm than good.

Functional Programming is entering industry from academia. Academic terms, like Functional Programming, have the luxury of never being defined. Researchers learn to "talk the talk" by reading and publishing papers and discussing with other researchers.

However, as more and more commercial software is written using Functional Programming techniques, we see the need to explain what it is we do. We want to teach newcomers. We want to explain to project managers and "non-programmer" leaders why we do what we do. When our programs are run for their effects, saying we should avoid them doesn't make much sense.

The definition should help us understand what we do and why. But further, the definition should generate new directions of discussion. A good definition gives us the lay of the land—and with that we can go exploring.

There is a lot of in-fighting in the FP world. A unifying definition could subdue some old flamewars and give an outsider something to think about. Right now, FP often looks like a bunch of fights not worth having. What if it looked like a fruitful discussion? What if it looked like an intuitive way to think about software?

I think I've got a good definition. I'm sharing it with people now to help it grow and develop. Each time I share it, I learn something about how to express it. I'd like to turn it into something significant, and when it's strong and healthy, release it into the world. It's too involved to share it here, but you can see the beginnings of it in this article about programming paradigms.

Functional Programming can help a lot of people create better software. It's not better than other paradigms. But having more paradigms to choose from is better than having fewer. It's not incompatible with Object-Oriented Programming or Imperative Programming. They're different perspectives for analyzing a problem. Each helps us develop better solutions.

We need a useful definition of Functional Programming. It has to explain what industrial programmers (non-academicians) actually do—including writing software with effects and mutable state. A good definition can open new doors of discovery and jumpstart a literature. And if nobody else is doing it, I'll give it my best shot.

Rock on!
Eric Normand <eric@purelyfunctional.tv>

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