Why functional programming is not so often used to write games? [closed]

tl; dr: it’s not popular, it’s hard to find specialists, there’s not enough materials.

There are several reasons, mainly historical and temporary .

Historically, the imperative style began to be applied earlier, since there are fewer transformations from programs in this style to a machine-readable understanding. Therefore, the main share of games was written in this style. The region developed, acquired architecture, being built on the achievements of predecessors, which did not use the functional style, as a rule.

Not without exception, of course. Abuse (1995) and some Naughty Dog games are written with a lot of Lisp . How much "functional" is used there is questionable, but if not, it is not clear why there was any use of lisp at all, right?

Now the use of functional programming in the entire software development industry (including games) is quite rare. “Big igrostroy” refuses it, because the specialists are expensive : it happened with Naughty Dog when they were bought by Sony, they were forced to refuse, saying that “you will not work otherwise with ours”. The same applies to the players-modelers - "functionals" among them very few.

In many ways, this relies on how programmers become in our time . It's not a secret that many have become programmers from the desire to engage in the development of games (I am one of them), and if you have the desire, you begin to search for materials yourself. And come across those materials that are most in the district. And usually they are not about functional programming.

Functional programming is cool, but “nobody uses it in practice” because there are no specialists (who are profitable to hire), and they do not appear because there is no demand for them. The situation looks like a vicious circle that can be broken, gradually teaching professionals to work in a functional style, which requires appropriate technologies that can be introduced gradually (to develop a motive), and then training materials (to support the motive).

But if you forget about all this, you need to understand that the functional area is not a silver bullet that can do anything. And it is appropriate far from everywhere. It is perfect for describing the strict logic of a small volume , where performance will not soar much.

Performance basically kills allocations , which are very typical for functional style because of the preference for persistent data structures , if there are not many of them, there will be no problems.

The situation may change if someone implements a powerful embedded functional language that optimizes working with memory. Theoretically, this could be a prediction of where it will be released and maximum reuse of what already is, simple algorithms generated by the compiler right on the spot.

In order for the game to work at 60 frames per second, there is only about 16 milliseconds per frame, so the basis of the game is better to write on what works well and works smartly : if it is predictable, then the code in the functional style will work fine and the performance will not be upset will be. "Functional core, imperative shell" ( Gary Bernhardt, Boundaries )

_{In the work, this combination can be seen, for example, in re-natal , the bright React Native, connected to the functional ClojureScript. But even the popularity of React Native itself is not transcendental, people do not believe that pushing the whole JS runtime into the application will be of benefit to it.}

Some interesting reports with ClojureTV on the topic:

• Report on the creation of adventure on Clojure (with tricky questions at the end)
• JavaFX + Clojure for game development tools
• Implementing almost traditional ECS in ClojureScript