I'll have to give this a shot for some of the Rust server work I'm doing. progscrape.com uses a lot of tricks to boot quickly specifically because of the edit-compile-run cycle being slow (mostly deferred loading of indexes, etc).

My current day job @ Gel has me working on a Rust socket frontend for some pretty complex code and that could also be pretty interesting.

It seems to require that you choose a good "cutover" point in your codebase, but TBH that's probably not too hard to pick. The HTTP service handler in a webserver, the socket handlers in non-web serving code, etc.

It does appear to have a limitation where it will only allow the main crate to be hotpatched. That's less than ideal, but I suppose the convenience might justify some code structure changes to allow that.