C# has the `DebuggerDisplay` attribute: https://learn.microsoft.com/en-us/visualstudio/debugger/usin...

One of the nice things about Rust's RFC process for new features is they answer questions like this: https://rust-lang.github.io/rfcs/3191-debugger-visualizer.ht...

edit: actually, I guess that focuses more on the debugger side, and less on the language side, so not a great answer to your question.

A slightly different thing - Visual Studio allows you to create custom visualizations for any live debug data. This is absolutely wonderful.

Not exactly but for shared libraries in general it's possible to ship some accompanying Python that will get installed and automatically loaded by GDB.

You can even embed that Python script within the shared object using some scary ELF tricks - I was surprised, to say the least, to discover this is supported.

Perl has Smart::Comments, original work by the brilliant Damian Conway.

https://metacpan.org/pod/Smart::Comments

I guess repr is kind of similar in python but not really

Not that I know of. But I’d certainly like to know that I missed it