> On Oct 12, 2017, at 9:57 PM, Kevin Nattinger via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> That is reflected in the fact that over half the methods in the main Sequence
> definition* make no sense and are not well-defined unless there is a
> well-defined order to the sequence itself. What does it even mean to
> `dropFirst()` in a Set?
It means to skip the first element the set would normally have given you. Which
element this will be may be arbitrary, but this is still not useless:
set.dropFirst().reduce(set.first!, …)
Even elementsEqual(_:) does tell you something potentially valuable: Whether
two instances will end up giving the same result when processed by an
ordering-sensitive algorithm.
We should change the name to something like orderEquals(_:), and maybe change
the lexicographicallyPrecedes(_:) method to something analogous like
orderPrecedes(_:), and then be done with it.
--
Brent Royal-Gordon
Sent from my iPhone
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