[swift-users] Associativity of && and || operator

[Howard Lovatt]

To me it would be surprising if && grouped differently than * or &; since
it is closely associated with boolean-and, which in turn is the equivalent
operation to multiply in Boolean logic.

On Fri, 17 Feb 2017 at 7:56 pm, rintaro ishizaki via swift-users <
swift-users at 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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-- 
-- Howard.
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