[swift-evolution] [Proposal] Random Unification

Alejandro Alonso aalonso128 at outlook.com
Tue Jan 2 02:35:09 CST 2018

Hello swift evolution once again, I’ve been hard at work considering every email and revising the proposal. I’ve made lots of changes and additions to the proposal to discuss some problems we’ve had (T.random), and walks through detailed design. You can see the proposal here: https://github.com/apple/swift-evolution/pull/760 .

A big issue that lots of people pointed out was `T.random %` and to remove it completely from the API. To give a gist of why I continue to support T.random:

1. Modulo bias misuse is only a problem to types that conform to `BinaryInteger`. Why remove this functionality if only a portion of the types have the ability of misuse. `Double.random % 10` is a good example of where modulo isn’t implemented here as it produces the error, “'%' is unavailable: Use truncatingRemainder instead”.

2. `Int.random(in: Int.min … Int.max)` doesn’t work. For developers that actually rely on this functionality, the work around that was discussed earlier simply doesn’t work. `Int.min … Int.max`’s count property exceeds that of `Int`’s numerical range. A working work around would be something along the lines of `Int(truncatingIfNeeded: Random.default.next(UInt.self))` which creates a pain point for those developers. As the goal of this proposal to remove pain points regarding random, this change does the opposite.

I’m interested to hear if anymore discussion around this, or any other issues come up.

- Alejandro

On Sep 8, 2017, 11:52 AM -0500, Alejandro Alonso via swift-evolution <swift-evolution at swift.org>, wrote:
Hello swift evolution, I would like to propose a unified approach to `random()` in Swift. I have a simple implementation here https://gist.github.com/Azoy/5d294148c8b97d20b96ee64f434bb4f5. This implementation is a simple wrapper over existing random functions so existing code bases will not be affected. Also, this approach introduces a new random feature for Linux users that give them access to upper bounds, as well as a lower bound for both Glibc and Darwin users. This change would be implemented within Foundation.

I believe this simple change could have a very positive impact on new developers learning Swift and experienced developers being able to write single random declarations.

I’d like to hear about your ideas on this proposal, or any implementation changes if need be.

- Alejando

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