Left associativity is most likely just a holdover from the C family–not
conforming with it would break expectations for programmers coming from these
languages. And as you mentioned, the compiler will short-circuit the condition
and stop evaluating as soon as it encounters a false condition, so there’s no
measurable benefit.
Saagar Jha
> On Feb 17, 2017, at 12:54 AM, rintaro ishizaki via swift-users
> <swift-users@swift.org> wrote:
>
> Hello all,
>
> Why the associativity of Logical{Conjunction,Disjunction}Precedence is "left"?
>
> If you write: A && B && C, it's grouped as (A && B) && C.
> This means that the && function is always called twice: (&&)((&&)(A, B), C).
> I feel "right" associativity is more natural: (&&)(A, (&&)(B, C)),
> because the && function is called only once if A is false.
>
> I know that redundant && calls are optimized away in most cases.
> I also know C and C++ standard says: "The && operator groups left-to-right",
> and most programming languages follow that.
>
> But why not "right" associativity?
> What is the difference between logical operators and ?? operator that has
> "right" associativity?
>
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