[swift-evolution] [swift-evolution-announce] [Review] SE-0099: Restructuring Condition Clauses

Brent Royal-Gordon brent at architechies.com
Fri May 27 18:35:48 CDT 2016

> 		https://github.com/apple/swift-evolution/blob/master/proposals/0099-conditionclauses.md

> 	• What is your evaluation of the proposal?


I am not a fan of this syntax. `;` reads very strongly as a statement ender to me, and yet at the same time, it's still visually quite close to `,`. My first impression was that the proposal had an embarrassing typo in the very first example.

My suggestion would be to reuse our normal && operator:

		x == 0 &&
		let y = optional &&
		z == 2
		else { ... }

This would obviously be a built-in `&&` separate from our existing, infix operator `&&`. (Well, unless we make `let` and `case` clauses return Bools in an `if` statement, and somehow teach the compiler that `&&` will return `false` if a binding fails.) But there is no ambiguity about the meaning of this code. It is obvious that both conditions have to succeed, and it is obvious that `z == 2` was not meant to be another optional binding. Honestly, in some ways it's more understandable than the status quo.

> 	• Is the problem being addressed significant enough to warrant a change to Swift?

Maybe, if we have a good enough solution. I don't think this is it.

> 	• Does this proposal fit well with the feel and direction of Swift?

I think it's kind of neutral, honestly.

> 	• If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?

Most languages I've used have `if` statements which take a simple boolean expression, so they don't face this problem.

> 	• How much effort did you put into your review? A glance, a quick reading, or an in-depth study?

Pretty much a glance.

Brent Royal-Gordon

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