[PreRFC] enum-variant-types

[Jules-Bertholet]

A more general version of this feature has been discussed under the name "pattern types".

Ranged integers via subtypes

Pattern types MVP

Thoughts on pattern types and subtyping

Recently, there has been a lot of discussion about some form of "pattern types" or "value-restricted types": types that are just like a base type, but restricted to a narrower set of values. I've been thinking about this for a while, and there are some important subtleties to consider, relating to subtyping. Introduction @oli-obk's post is a good introduction to this feature. The basic idea is that you take a type, say i32, you take a pattern that matches on that type, say 1..3, and you get a …