[ernst_klim]

TBH I think it's rather a post-hoc rationalization of why the language is not popular.

> there's multiple standard libraries

Scala has a far more fragmented ecosystem with Cats, Scalaz, Zio and Akka. C++ and Java have a bunch of stdlib extensions like boost, Guava, Apache Commons etc.

> many documents are barely more than type signatures

Can be said of most of Java, Kotlin, Scala, Erlang etc etc. Just compiled javadocs, sometimes with a couple of unhelpful lines.

> data structures aren't printable by default

Neither they are in C++

I think the real reason it's not popular is that there are languages which solve more or less the same problems of system programming but look far more familiar to an avg. programmer who was raised on C++ and Java.

[dmpk2k]

Maybe it's post-hoc?

I wanted to use OCaml since 2002, since it was a GC'd language with good performance, achieving a lot with relatively few lines of code. Being a language nerd, I was (am?) positively inclined to the language. Yet there was always something that made it notably less pleasant to solve my current problem in than in than some other language.

If it had trouble getting traction with me, that's bad news.

Meanwhile the mainstream has progressed a lot since 2000. GC is the standard, closures are normal, pattern matching and destructuring are increasingly so. While HM-style type inference is not mainstream, local type inference is (and I'm no longer convinced that global type inference is the way). Algebraic data types aren't unusual anymore.

A few years back I just threw in the towel and went with Rust; this happened after I volunteered to improve OCaml's gdb support (including DWARF hell), which went nowhere. I wish Rust compiled faster, and a GC'd language is usually more productive for my problems, but in every other regard it stole what should have been OCaml's thunder. And when popular successor languages eventually appear, they'll do it even better.

[creata]

Off-topic: What language would you say is the closest thing to "Rust with a GC"?

(Rust has refcounting, but it's slow, and needing to handle cycles manually limits its usefulness.)

[hollerith]

GC was standard already in 2000: Perl, Python, Ruby, Java and JS all had GC from day 1.