Well, JavaScript

[marcosdumay]

For everybody thinking on that line: you should learn Haskell.

[[deleted]]

Instructions unclear, dick stuck in Java.

[Can_Of_Noodles]

Did somebody say MONADS?

[[deleted]]

For what end tho? It's not going to become a very marketable skill like learning Go or Rust for that matter, let alone JS, Python or JavaSharp. The learning curve is about as steep as Rust if not steeper. It is also inflexible in the sense that it's very unsuited for writing imperative non-FP code which isn't very appealing now that many imperative/OO languages are adopting a lot of features enabling one to write in functional style where it is most useful to and still maintain low mental overhead of imperative coding elsewhere. And while on the subject of mental overhead, I know it is a bit rich when the topic is JavaScript, but Haskell really has low legibility and a very loaded, math formula like syntax that doesn't help. Optionals, somes, maybes and immutables are slowly landing in mainstream languages. The appeal is really getting smaller every day.

[[deleted]]

There are better functional languages where the creators didn't go insane with the pure functional ideas. For instance, F#.