Generated functions are an escape hatch that allows you to bypass the regular multiple dispatch mechanism. As such, you should only use them if regular multiple dispatch can’t get you what we need. Since multiple dispatch is a very powerful abstraction, you should think carefully about whether your problem is of sufficient complexity that it is beyond the reach of regular multiple dispatch. If you use generated functions, the compiler will have less information about what the function is going to do, which may result in:
- Slower compile times due to excessive specialization (and invocation of the generated function).
- Various sorts of world age issues
- Reduced performance
- Reduced debuggability
- Crashes if you return something invalid from a generated function (the compiler isn’t particularly hardened against invalid IR, because usually it is generated from the frontend and thus correct by construction).
Or in other words, you topple over a domino with a nuke, but maybe blowing on it is enough (lest you accidentally disintegrate it or cause a nuclear winter). Generated functions are there if you need them, but even those who well know their power try to avoid them if possible.