[swift-evolution] Proposal: Optional Binding Shorthand Syntax

[Chris Lattner]

> On Dec 6, 2015, at 1:38 PM, Tyler Mandry via swift-evolution <swift-evolution at swift.org> wrote:
> 
> What isn't clear to me from Chris's or John's comments is why the `if let x? = foo` syntax was taken away. Was it for backward-compatibility? 

FWIW, that syntax hasn’t been taken away, it just means something different now.

	if let x = foo() {

captures is privileged syntax for testing an optional and binding to the thing inside of it.  The patch I linked to moved away from this, but at great cost: it uglified lots of common code.  Swift privileges optional in a number of ways (e.g. it is the result of as?, try?, etc) and the standard library uses it pervasively as well.  Optimizing for that common case makes sense.

-Chris