> I don't think it's possible to write a tool like ripgrep with its performance profile in a GC language.
I think it is possible to make a language that has both a GC and a borrow checker, treating the GC types as a third level next to the stack and the heap, where complex referencial cycles can bé promoted to the GC, but the defaults push you towards fast execution patterns. Don't know if such a language would be successful in finding its niche. The only way I could see that, is of a non-gc mode could be enforced so that libraries can be written in the more restrictive, faster by default mode, while being consumed by application developers that have less stringent restrictions. This is no different in concept than Python libraries implemented in native languages. Making it the mode be part of the same language could help with prototyping pains: write with the GC and then refactor once at the end after the general design is mostly found.
My standard of evidence here is existence. There are many greps written in a "GC language," and none of them have a broad performance profile in the same category as ripgrep (or other greps written in C and C++).
> This is no different in concept than Python libraries implemented in native languages.
If that's true, then why isn't there a fast grep written in Python? IMO, it's for the same reason that tools like csvkit are slow. Once you get to the boundary between GC and non-GC, some kind of cost gets paid. Now maybe Python is paying higher costs here than your hypothetical language, but who knows. Without actual existence, I find this sort of hypothetical to be very uncompelling. It's too broad of a stroke.
> I think it is possible to make a language that has both a GC and a borrow checker, treating the GC types as a third level next to the stack and the heap, where complex referencial cycles can be 'promoted to the GC'
It's doable but there are a few issues with that whole idea. You need the ability to safely promote objects to GC-roots whenever they're being referenced by GC-unaware code, and demote them again afterwards. And if any GC object happens to control the lifecycle of any heap-allocated objects, it must have a finalizer that cleans them up RAII style to avoid resource leaks.
I think it is possible to make a language that has both a GC and a borrow checker, treating the GC types as a third level next to the stack and the heap, where complex referencial cycles can bé promoted to the GC, but the defaults push you towards fast execution patterns. Don't know if such a language would be successful in finding its niche. The only way I could see that, is of a non-gc mode could be enforced so that libraries can be written in the more restrictive, faster by default mode, while being consumed by application developers that have less stringent restrictions. This is no different in concept than Python libraries implemented in native languages. Making it the mode be part of the same language could help with prototyping pains: write with the GC and then refactor once at the end after the general design is mostly found.