Syntax IMO. I know it's obnoxious, but the reality is most people read C like languages, not Lisp.

It's the learning curve.

There is a very DIY approach with composition, with lots of library choices. This makes it tough for beginners and intermediate programmers to jump right in and be productive.

That plus functional programming, plus immutable defaults, plus Lisp, filter out developers who don't have a lot of experience, dedication, or a mentor.

The more I learn though, the more I love it.

lisp turns a lot of people off - it does require some retraining of your mind. when people need to get shit done this friction is too great, and so they fall back on other tools.

going to do advent of code in clojure this year though to force myself back into it - it's a great language.

I hate everything that runs on the jvm, only use kotlin for Android stuff. I dont think I am the only one. Simplicity=python, performance=go.

Memory usage is absurd and when you cap it, the performance is worse than Scratch.

Because it's not easy.

You need the right balance of "easy" and "simple" and Clojure does not have it.

2 decade ago, I used to love Scheme-like languages, they seemed so elegant.

But after struggling hard trying to introduce them into companies, I gave up. In contrast, I introduced Go into 3 companies and numerous teams so far and it was so easy for it to gain adoption.

I tried to use Clojure a few weeks ago. I have two projects for it: the first is that I have a "TOML test matrix" where I compare different TOML implementations against the test suite. This works by feeding a binary a TOML document which then outputs a description of that in JSON. I set that up for a whole bunch of languages.

The second is instaparse, which I'd like to use to quickly test a TOML document against the TOML ABNF.

I couldn't get either to work. As in: I can't even get very simple examples to compile. The tooling is super confusing and weird. I appreciate that a lot of tooling you're not familiar with can be confusing and weird, but I managed to get to a lot of languages for my TOML test matrix to work, including many where I'm not familiar with. For some that took some time and patience, but that's okay. Clojure is the only one thus far where I just gave up (for now anyway).

So at least part of the answer to "why isn't it more popular" is "the tooling isn't very good". Maybe the tooling is "simple" by Hickey's definition of that, but it sure isn't "easy" by my definition, and in the end, "easy" does matter, especially for these kind of things.

Sorry, but this is plain wrong. Clojure is a functional first language with an extremely powerful macro system. JavaScript has ad-hoc monkey patching and a heavy toolchain requirement to enable immutability.