I've used Perl 6 for IRC bots. The ease of writing parallel code, nice OO model, multi dispatch, and subsets make it very pleasant to do them in Perl 6. Here's a bot I wrote that listens for GitHub webhooks and reports new commits and PRs: https://github.com/perl6/geth and here's another one that's just a bunch of random features: https://github.com/zoffixznet/perl6-buggable/

I also heard people say grammars are the most note-worthy feature of Perl 6 and people basically use them to quickly hack up a nice little micro-language in which they then attack their problem. Before I came to Perl 6 I was dumb as shoe when it came to writing parsers, but I find it trivial to do with Perl 6 grammars.

Do I like it? Although I'm obviously biased, I love the language. It lets you write beautifully concise, yet still readable, code. It even lets you use much more readable syntax for regexes. Somewhat regretfully, it made it very difficult for me to learn other languages, as in them I end up writing 3x, 4x, 6x the amount of code and I keep getting reminded of Larry Wall saying Perl 6 would be the last language you'd learn. In Perl 6 I can "talk"; in other languages, I write "code".

However, while the language is fantastic, the implementation still has a lot of work to be done to polish it off. It's basically a 1.0 release. Unlike Go, Rust, or Swift, there isn't a giant corporation behind Perl 6 that can just throw money at problems until they disappear. Compared to other languages, some things are still unoptimized and are much slower. I spotted some leakage that makes it problematic for very-long-running (months) programs. About 65 new bug tickets are opened per month. The test suite is pretty sparse in some areas (which is the likely reason for many of the new bug tickets). But... three new core developers joined this January, so hopefully all that will get improved pretty fast.

Someone in the comments also mentioned the baby-sized ecosystem... Since Perl 6 lets you use C libraries without needing to compile anything, people wrote stuff like Inline::Perl5 and Inline::Python that let you import and even subclass stuff from Perl 5 and Python. And that's a bit of a double-edge sword: yes, it's trivial to use libraries from Perl 5 and Python, but it also stunts the ecosystem; no one has enough motivation to re-invent the wheel in Perl 6 when the wheels from other languages are reasonably usable.

SuperCollider is a platform for audio synthesis and algorithmic composition, used by musicians, artists, and researchers working with sound. It is free and open source software available for Windows, macOS, and Linux.