Thank you Ian, that’s very helpful context.
I understand the concern about implicit loops and the general bias against
them in the language design.
My thought here was that this case might be closer to the existing slice
expansion at call sites (f(xs...)). In both cases we’re conceptually saying
“apply this operation elementwise.” One is a function call, the other is a
channel send.
I agree it does expand into a loop, but it’s a loop Go programmers already
write constantly in channel pipelines. I hoped that the consistency with
the existing ... operator, and the frequency of the for _, v := range xs {
ch <- v } pattern, might make it worth considering as one of those “common
special cases.”
I appreciate the feedback either way.
пятница, 15 августа 2025 г. в 20:28:15 UTC+3, Ian Lance Taylor:
On Fri, Aug 15, 2025 at 10:17 AM Ruslan Semagin <[email protected]>
wrote:
>
> I recently submitted a proposal to add slice expansion to channel send
statements in Go:
>
> ch <- X... // X is a slice, array, *array, or string
>
> The proposal was closed very quickly in the tracker before any community
discussion could take place. I would still like to get broader feedback
from Go developers, so I’m starting this discussion here.
>
> The idea mirrors existing slice expansion in function calls (for example,
append(dst, src...))
Note that slice expansion in function calls does not expand into a
loop. When using "src..." the slice "src" is passed directly to the
"...vals" parameter.
Your proposal does expand into a loop. That is a property that the
language reserves for some common special cases, such as conversion
between string and []byte or []rune. In general the language has a
bias toward not expanding into loops, as it means that the execution
time of the statement is unpredictable. We would probably only do that
for a case that occurs frequently and that can't be easily written as
an ordinary loop.
Ian
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