Is this surprising? I don't see an ecosystem of languages targeting the Go runtime, in contrast to the JVM, Javascript, Erlang, MS CLR...

I don't think this is necessarily a matter of popularity or maturity. I don't know of languages that compile to Python bytecode, either. In Python's case I suspect the VM is so optimized for Python that it makes an inflexible target for other languages: I don't know enough about this subject to say whether that's the case for Go as well.

> Is this surprising? I don't see an ecosystem of languages targeting the Go runtime, in contrast to the JVM, Javascript, Erlang, MS CLR...

I think I'm surprised in general that no language targets the Go runtime. A ML built on Go could probably be popular, lots of people would like features from it.

Not exactly bytecode but Hy https://github.com/hylang/hy is a dialect of Lisp that compiles to Python.

Hy actually compiles directly to Python AST, not to Python. For a Lisp that compiles to Python, see Hissp: https://github.com/gilch/hissp

> - There's Joker (https://github.com/candid82/joker) with a similar mission to Babashka, but commonly used as a linter.

Joker is a Clojure interpreter, mostly used as a linter in the community but can be used as a runtime as well.

By "built on Go" I meant like Java: you can use Go libraries and compile it as you would compile Go code, to a single binary.

I see! "Built on X" would usually refer to what language something is built in, while what you're talking about is "interoperability" with the host language.

But yeah, unfortunately Joker doesn't do interop, which is sad because it's one of the coolest features of the Clojure language.