Why Isn't Functional Programming the Norm? [video]

The top comment on YouTube raises a valid point:

> I've programmed both functional and non-functional (not necessarily OO) programming languages for ~2 decades now. This misses the point. Even if functional programming helps you reason about ADTs and data flow, monads, etc, it has the opposite effect for helping you reason about what the machine is doing. You have no control over execution, memory layout, garbage collection, you name it. FP will always occupy a niche because of where it sits in the abstraction hierarchy. I'm a real time graphics programmer and if I can't mentally map (in rough terms, specific if necessary) what assembly my code is going to generate, the language is a non-starter. This is true for any company at scale. FP can be used at the fringe or the edge, but the core part demands efficiency.

In terms of performance, the way we build applications today is such a low bar that IMO it opens the door for functional programming. Even if it is not as fast as C or raw assembly - if it is significantly faster than Electron, but preserves the developer ergonomics... it can be a win for the end user!

I created an Electron (TypeScript/React) desktop application called Onivim [1] and then re-built it for a v2 in OCaml / ReasonML [2] - compiled to native machine code. (And we built a UI/Application framework called Revery [3] to support it)

There were very significant, tangible improvements in performance:

- Order of magnitude improvement in startup time (time to interactive, Windows 10, warm start: from 5s -> 0.5s)

- Less memory usage (from ~180MB to <50MB). And 50MB still seems too high!

The tooling for building cross-platform apps on this tech is still raw & a work-in-progress - but I believe there is much untapped potential in taking the 'React' idea and applying it to a functional, compile-to-native language like ReasonML/OCaml for building UI applications. Performance is one obvious dimension; but we also get benefits in terms of correctness - for example, compile-time validation of the 'rules of hooks'.

- [1] Onivim v1 (Electron) https://github.com/onivim/oni

- [2] Onivim v2 (ReasonML/OCaml) https://v2.onivim.io

- [3] Revery: https://www.outrunlabs.com/revery/

- [4] Flambda: https://caml.inria.fr/pub/docs/manual-ocaml/flambda.html

They already said they were working in games. None of what you said applies to that field.

I would say "real time graphics" is one of the niches FP is not well suited for, most business software doesn't need to work at the level of the machine.

There is certainly prior art for complex games running smoothly in Haskell: https://wiki.haskell.org/Frag

This particular solution used functional reactive programming, essentially a composition of signal/event processing functions/automatons.