This is exactly the syntax for enum case patterns in switch statements. You're asserting that it's inconsistent with something, but I don't see any inconsistency. I don't understand what you mean by right-to-left assignment or inout variables.
Robert's example is confusing because the variables are interestingly named, but it is not a real-world error that can be made because you do not have variables named x and y, and the compiler would shout errors at you in short order if you tried to use them. On Sat, May 6, 2017 at 10:12 Adrian Zubarev <adrian.zuba...@devandartist.com> wrote: > There is nothing consistent in the following example: > > let (x: a, y: b) = (x: 0, y: 1) > > Labels are not simple descriptors, they signal that the assignment for the > RHS will happen to some constant associated with the label. The assignment > direction is from right-to-left! Labeled tuple destructuring breaks this > rule. Furthermore you’re not allowed to think of a and b as if they were > some inout variables for the purpose of the assignment there. > > The syntax is ambiguous to the rest of the language and also exactly the > case why the following code is not only confusing but simply mentally wrong: > > let (x: Int, y: Double) = (3, 1) > let result = Int + Double // 4 > > > > -- > Adrian Zubarev > Sent with Airmail > > Am 6. Mai 2017 um 08:06:30, Xiaodi Wu (xiaodi...@gmail.com) schrieb: > > The identifier after a colon is *never* a type in any pattern matching, > and there's no need of which I'm aware to support type annotations in > pattern matching. We put colons after labels, and the current syntax is > perfectly consistent here. What is the defect you're trying to cure? > On Fri, May 5, 2017 at 22:42 Brent Royal-Gordon <br...@architechies.com> > wrote: > >> Sorry for wrecking the threading, but any chance we could change the >> syntax to: >> >> let (x myX: Int, y myY: Int) = ... >> >> That would ensure the identifier after the colon was always treated as a >> type. I suppose if you wanted to infer the type, it'd be: >> >> let (x myX, y myY) = ... >> >> -- >> Brent Royal-Gordon >> Sent from my iPhone >> >> On May 5, 2017, at 12:04 AM, Adrian Zubarev via swift-evolution < >> swift-evolution@swift.org> wrote: >> >> If we ban reordering now, than I don’t see choosing different names in >> tuple destructuring as a strong argument of allowing labels there let >> (x: a, y: b). They’re literally the same as one would write comments >> inside the destructured tuple let (/* my x */ x, /* my y*/ y). >> >>
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