These are great and essential tools for debugging, but they could be a lot better:

• They are painful to conditionally insert into the code because the syntax is very intrusive
• Turning them on and off requires recompiles

Thought: what if we added a scheduling directive for print_when() that would inject the print when the func is evaluated? (No need for print() since that's just print_when(true))? And added some optional controls via env var (eg print_when_env("ENV_VAR_NAME")?)