Yeah, so functional programming - it has a long history, like you said, beginning with Lisp. There was a paper in 1958 where John McCarthy described the language, and the challenge that they faced at that time was “How do we actually write papers about programming and ideas in programming? Do we just do it all in Assembly? Which machines Assembly do we use?” (there was no standard back then) and he proposed a language that was much higher level than Assembly that you could easily implement on any machine, and then say “Well, this will be a good language for talking about programming, and describing algorithms and things like that.” He never thought it would be a real language that you would actually run on a computer, but his grad students did and they implemented it, and it just ran from there in the lab because it proved to be so useful.

This was also at the same time as Fortran was being developed. Fortran was the first non-Assembly-level programming language, but what’s interesting is that Lisp was done by a team of grad students in university at MIT, and Fortran was like a multi-billion dollar project… So it always had this bootstrapping route. Anyway, that’s a little bit about Lisp.

[ ] Functional programming has sort of evolved over time to be this paradigm that uses functions, that uses Lambda calculus… It grew mostly in Academia because of its roots in math, roots that go back to Lambda calculus and theorem proving, stuff like that. And recently it’s gotten a lot of attention in the industry; no one really knows why… I’ve tried to figure out if there’s some event or something like that, but what I can see is that big names in the industry have been warning people about functional programming - we need it, and it’s better than object-oriented for some things like concurrency, for parallel programming…

I actually want to take a very simplifying view of why it’s increasing in popularity. I think the size of the industry, the number of programmers is just growing by itself, it’s doubling every five years, so what we’re seeing is that small portion of people who were always into functional programming are growing, and because of the internet they can connect no matter where they are in the world, so now we’re hearing about it. It’s just the network effect.

So the 5% of the industry that cares about functional programming - I’m just throwing that number out there, I just want a small number - is now a sizeable absolute number of programmers. And coupled with the fact that most software now, it doesn’t matter what language it’s written in, because it’s running on a server in the cloud somewhere, and it’s not running on somebody’s machine; that was a big obstacle back in the day, to like what languages you could actually write software in… I think that it’s just an opportunistic thing, just being able to run everything you want.