Re: [DISCUSS] Should RFCs for new functions include a userland polyfill/reference implementation?

در تاریخ جمعه ۴ سپتامبر ۲۰۲۶، ۱۶:۳۴ Larry Garfield <larry@garfieldtech.com> نوشت: > On Mon, Aug 31, 2026, at 9:57 AM, Tim Düsterhus wrote: > > Hi > > > > On 2026-08-25 17:34, Larry Garfield wrote: > >> And it would also give us a target to benchmark against to see if > >> putting it in C really has a performance benefit. > > > > I believe performance should not be a factor in deciding what should be > > part of the stdlib and what should not: Performance is a moving target > > and what might be true today might no longer be true tomorrow - with > > folks generally having wildly incorrect assumptions about what actually > > is “slow”. > > > > Once we add something to the stdlib we need to maintain it for the next > > 15+ years. (Broad) usefulness and good API design must be the deciding > > factors for whether something should be in the stdlib or not [1]. > > I agree that good API design should be the primary factor. However, I > disagree that performance is a non-factor. Yes, performance comparisons > will shift over time, but that doesn't make it unimportant. It is one > useful data point among many. > > If, to use the current example, benchmarking shows that > array_str_contains() is 50% faster in C than in user-space, that's a very > different conclusion than if we find it is 0.5% faster. The former > provides an argument for inclusion, though obviously not a slam dunk (as > overall API design is a larger factor). In the latter case, we know that > performance is a non-argument and can be dismissed. > > We stress over the performance impact of certain generics approaches, we > spent a lot of time thinking about performance implications for hooks, or > PFA, or pipes. stdlib functions should not be exempt from that > consideration. They should just be considered appropriately and in context. > > --Larry Garfield > -------- Thanks, Larry. I agree that performance is a relevant data point. I have already conducted a real-world usage analysis, and the RFC now includes both the summary table and a link to the complete JSON dataset. I will also prepare a benchmark comparing the C implementation with representative userland implementations (such as foreach loops and array_filter-based approaches) across different array sizes and match positions, and share the results.