On Sun, Dec 15, 2019 at 11:28 PM Raymond Hettinger < raymond.hettin...@gmail.com> wrote:
> * The corresponding mathematical concept is unordered and it would be > weird to impose such as order. > I'm with Raymond in not wanting sets to maintain insertion (or any) order. Even though I don't doubt that Larry--and no doubt other folks, from time to time--have a use for an "ordered set," I feel like it is bad practice to encourage that way of thinking about sets and using them. Admittedly, I was only lukewarm about making an insertion-order guarantee for dictionaries too. But for sets I feel more strongly opposed. Although it seems unlikely now, if some improved implementation of sets had the accidental side effects of making them ordered, I would still not want that to become a semantic guarantee. That said, having OrderedSet in collections module would be fine by me. It might have different performance characteristics, but so what? It would be a different class that folks could use or not, depending on how they felt about its behavior and performance profile. -- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th.
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