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

David Hart david at hartbit.com
Mon Jun 6 02:26:57 CDT 2016

> 	• What is your evaluation of the proposal?

+1 I’ve always been annoyed by the complicated grammar of condition clauses. This proposal simplifies them and makes them easier to understand and teach.

Especially, I regret that the syntax for A && B is different than B && A when A is a boolean expression and B is an optional unwrapping clause. It breaks a nice visual symmetry:

if a, let b = b {}
if let b = b where a {}

This proposal brings back the symmetry.

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

It is.

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

It brings more consistency, and it breaks the syntax. So it should be introduced for Swift 3.

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

I haven’t used languages which had anything else than boolean expressions in their condition clauses, but I’ve always expected the syntax of A && B to be symmetrical to B && A.

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

A long read of the original discussion and the review discussion.

> More information about the Swift evolution process is available at
> 	https://github.com/apple/swift-evolution/blob/master/process.md
> Thank you,
> -Joe
> Review Manager
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