I've learned a bunch of different languages[1], but J (and its friends APL and K) has been both the one that I don't feel I have the patience to learn AND the one that I feel like I might fall in love with if I actually learned it.

The incomprehensible programs just seem to hint that there is some sort of maximal information density where every keystroke provides maximal productivity.

There's also something artistically appealing about starting at a program and making a deliberate one character change that makes all the difference ... although on the other hand, that's kind of scary too.

Here's a video that really illustrates the power of this paradigm: https://www.youtube.com/watch?v=a9xAKttWgP4

[1] - I learned (in this approximate order): C, Java, Lua, C#, Ruby, Python, Lisp, Forth, Prolog, Clojure, OCaml, Haskell, Erlang, F#, R, Racket, and Rust. I also took a look at languages like: ATS, Cyclone, C++, Idris, Agda, D, and Perl 6. Of all those languages it really feels like APL/J/K are the strange ones.

I struggled a lot too. I think the main issue is the problem domain in which these languages excel at.

I like compilers, systems programming, distributed systems... but math? statistics? I'm admittedly terrible at that and find it really uninteresting. It doesn't help that most literature on J tries to teach its language concepts showing you how to solve math problems. I have no need for a fancy calculator.

For what it's worth, I like K and Klong and found them very approachable. Basically because you can get away by writing Scheme with m-expressions.