This is how I keep feedback loops short:

- IntelliJ tells me any type issues instantly (I find this makes up some of the time for not having a REPL).

- Small tests kind of work like a REPL.

- watch.sh running in a terminal, re-compiles and runs the code I am working on. In your web server example, I would be testing the units rather than the whole composite program. I can click file references to jump to the error.

- Fast machine (M1)