Pitch: Genericizing over annotations like throws

[anandabits (Matthew Johnson)]

@Joe_Groff

Another interesting future direction we could take to address polymorphism over throws specifically would be to adopt typed throws , and make the error type an independent type argument of all function types. This would mean that a type that doesn't throw effectively throws Never , and one that throws without a type by default throws Error :

I’m very much in favor of a design in this direction for typed throws. Further, I think it’s important that throwing any uninhabited type is treated equivalently to throwing Never in terms of needing to use try when invoked and needing to handle errors, etc. I wrote about why in [Discussion] Analysis of the design of typed throws - #3 by Anton_Zhilin.

This design for typed throws would support abstracting over error types, including whether one throws at all or not which is great! That said, I think it would sit nicely along side a more general effect abstraction feature. They address related (even overlapping) but distinct use cases.