Range types for integers (or refinement types?)

Issue by BryanQuigley
Saturday Dec 13, 2014 at 03:46 GMT

For earlier discussion, see https://github.com/rust-lang/rust/issues/19801

This issue was labelled with: A-an-interesting-project, E-hard in the Rust repository

It seems like a natural extension of how variables (immutable by default, mutable if specified) are defined to allow the programmer to dictate a specific range of allowed values for an integer. If I know a value is only valid between 0-1000 the sooner I declare that the better it is for catching bugs, off by one errors, and more...

I'm not sure what exact syntax would work, maybe:

let mut(0,1000) x = 0i;

x is only valid from 0-1000 inclusive.

(Apologies if this is already possible, I've been parsing the docs trying to learn Rust.)

Start by reading the earlier discussion in Rust issue #19801 and the comments on this issue. Define the intended range or refinement-type semantics, including syntax and boundary behavior, before assessing whether the proposal fits the RFC process. Done means an agreed design that can be written as a complete RFC.