Uniquing elements in a Sequence

[soroush (Soroush Khanlou)]

@Paul_Cantrell

I’d suggest just uniqueElements(by:) or byValue: or byKey: instead of byProperty: , since “property” to me means the thing you declare with a type-level var / let , but the projection may be some derived value that is not literally a property of the elements.

Yeah, byProperty: is just a label for now to distinguish between this version and the (Element, Element) -> Bool version.

@jrose

I'll also note there are two kinds of unique , and the shell-programming uniq and the C++ std::unique are a more limited but more efficient one: remove consecutive duplicate elements. That's useful for data already known to be sorted, but probably more expensive than the Set implementation when it isn't.

Oh wow I forgot about this distinction. Either way, I think Ruby's uniq is more what we're after, rather than the shell's uniq.

@beccadax

I think that’s a good reason to make some versions of uniqued() be customization points, but I’m not sure it justifies a separate adjacent-only version on all collections.

Yeah, that could work really nicely with SortedCollection protocol discussion that's also happening.