I'm getting started with functional programming, which language would you recommend?

"Lisp is worth learning for the profound enlightenment experience you will have when you finally get it; that experience will make you a better programmer for the rest of your days, even if you never actually use Lisp itself a lot." — Eric S. Raymond, How to Become a Hacker

You misspelled Haskell.
- Raymond's document does not, and I believe never has, mentioned Haskell.
  I also disagree with him, given that it does recommend Java, but the quote is correct.

Why do you want to learn functional programming? If just for fun and learning, then you can’t go wrong with scheme.

Kinda funny, I've also been thinking about scheme as another option. Yes, (currently) it is just for fun and learning.
- Another great avenue into this world is Racket. The tooling is fantastic and the documentation culture is first-class.
GNU Guile or Racket. from the language side every scheme is a scheme though. it kinda depends what you want to do with it
SICP is great for a very general in-depth intro
- SICP is very hard for a beginner. I recommend little schemer.

Clojure always seems to be more popular than I expect it to be. Though I have no experience with it myself. It benefits from access to the JVM ecosystem as well I believe.

I love clj. in general it takes more of a pragmatic approach to functional programming than others. you get most of the purity for way less effort. same with specs over proper static types. it just ends up being a very enjoyable and productive language

I'd go with Erlang over elixir, but it sounds like you already have an interest in gleam.

FWIW: just pick one and get started. There are some major axes to consider: pure versus impure, lazy versus strict, static versus dynamic typing, but to kick off if you've done no FP before it's probably better to just go for it.

There are some really intriguing "next steps": SICP, the ML module system, the Haskell ecosystem, the OTP approach to state, but to begin with it's just worth getting used to some basics.

Yeah, I'll just go with Gleam :3

I'd just like to mention ML, as I myself found its type system really enlightening.

I assume this suggestion will get me torched for reasons I don't understand, but why not a multi-paradigm language like JavaScript/Typescript, or C#?

I feel like this is the way. It ensures you get exposed to multiple paradigms and can help you easily switch to a language that's more invested in one paradigm.

Elixir is quite amazing to write and read, the major libraries (Pheonix, Ecto, etc.) have excellent documentation, the tools are generally excellent and it is built on to BEAM which is amazing. But it is a dynamically typed language with all the pain that can incur. Of course, there are tools (such as Dialyzer) to give some amount of static type checking but they were not very good when I tried them some years ago. Using things that need mutation can also be a pain. Programming Elixir 1.6 Functional |> Concurrent |> Pragmatic |> Fun was the book I used to learn functional programming and Elixir and it served me well.

There are other good languages you can look into such as Ocaml (that has good free resources for new programmers) and Racket with the amazing free course you can find on OSSU.

I think it doesn't matter in what language you start, as long as it is the paradigm you are learning. You can still pick and choose the language later. Maybe start with a pure functional language, just to learn its concepts. Haskell comes to mind, but it kind of is not the best usable language in every day programming; its more academical nature in my opinion. I personally find Closure also interesting, but I'm not the biggest Java fan at all. At least the language is for practical usage.

My ₹1. It may depend on what you plan to write in it (for fun). The BEAM sounds great for long-running processes, but not as much for point tools; Erlang and co supposedly run slower than Python, which isn't fast either.

My other ₹ ;-) if you stick to the BEAM: OCaml sort of runs on it, as there is the Caramel project to replicate it (https://caramel.run/). One of the Erlang creators also ported Prolog to the BEAM (erlog), as well as Lua (erlua) and Lisp (LFE). Elixir is probably great, as it is inspired by Ruby (I found Ruby very pleasant, other languages have so much semantic noise).

Freebie! The BEAM inspired an inspirational design for parallel programming, the Pony language. I am somewhat sad development slowed down, it is a Rust killer.

₹ = Indian Rupee, in case anyone is wondering.

I did a functional programming course in university snd we learned Haskell and really loved it. By far my favourite subject in all 4 years of uni. Have never used it since tho but it was fun XD

gleam feels cozy.

If you’re interested in BEAM anyways, Gleam is just a lovely language to work with. It makes many functional principles easy to work with rather than mathematical. Although I don’t have any experience in Elixir, so I can’t judge how it compares in detail.

I love functional programming and hate object oriented. It's just how my brain thinks, I can and regularly do OOP, but I have to force myself to do it. Why not python? You can do BEAM in python, it's pretty easy to learn, and it's incredibly versatile, and you can program functionally in it too.

Python has OOP but basically no ergonomic support for FP? It doesn't even support tail recursion or currying, lambdas are very limited and there is no nice way to compose functions. Most of the python ecosystem heavily relies on OOP and in many cases global state. Not hating on python but even compared to other mixed paradigm languages like javascript it's on the less-functional side of things.

Erlang https://learnyousomeerlang.com/ If you know golang and recurrence it should be easy, google basically stole channels from Erlang and syntax from Swift. Like everything else, they just stealing stuff and claiming they're great. Fucking rich script kiddies.

Using concepts from other programming languages isn't stealing
- Let me rephrase it. It wasn't original idea. Scandinavian made it first Americans just copied and sold it.

F# is a decent introduction into functional programming. You can use .NET libraries and occasionally fall back to imperative code when needed.

Clojure is simple, is a lisp (huge plus since they are super simple and you gain access to a whole realm of languages), and practical. You can do anything from backend to frontend dev with it, and the philosophy and community are lovely.

Scheme is less practical but easier to start with.

Haskell is the least practical but isdefinitely beautiful and helps you understand things better.

Rust. It has all the good bits of functional programming but basically none of the bad bits.

Good bits:

Strong type system (though not quite as sophisticated as Haskell or OCaml).
Map, filter, etc.
First class functions (though lifetimes can make this a bit awkward)
Everything is an expression (well most things anyway).

Bad bits:

"Point free style" and currying. IMO this is really elegant, but also makes code difficult to read very quickly. Not worth the trade-off IMO.
No brackets/commas on function calls. Again this feels really elegant but in practice it really hurts readability.
Global type inference. Rust requires explicit types on globals which is much much nicer.
Custom operators. Again this is clever but unreadable.
Small communities.
Poor windows support (not a fundamental thing but it does seem to be an issue in practice for lots of functional languages).

I would advise going in the opposite direction, learning a purely functional language first to then being able to appreciate functional parts
That is beside the point of an opinionated list of the good and the bad, that will differ for others
The only things on the bad list that I agree with are top-level type inference and small communities. And ocamls windows support is terrible. Haskell's is more than ok now.
In Haskell, any style guide worth its salt requires annotations on top level functions, and many of them also require annotations on local bindings. This pretty effectively works around the problem.
Bad code will be unreadable in any language of course. But the other things don't themselves make code unreadable once you're actually familiar with the language and its ecosystem.
- Bad code will be unreadable in any language of course.
  Yeah I'm talking about good code, or at least not bad code. Let's not "no true Scotsman" this.
  Even for good code you don't need syntax highlighting to easily see which identifiers are function names and which are their parameters in Rust.

I've only used one, and I'm only mentioning it since nobody else has, but I recommend Lean; moreso as a second functional language if you want to build stuff as opposed to just learn the paradigm. It's mostly used in maths because it supports dependent types, but it was fine for writing simple scripts, and it can be easily compiled to binary formats. I don't like the package management system and toolchain complexity, but most languages kinda suck at that, imo.

I'd start with logo.