[swift-users] Set-uniqueness of instances with distinct hashValue

Dave Abrahams dabrahams at apple.com
Sun Oct 23 13:04:09 CDT 2016

on Sun Oct 23 2016, milos <swift-users-AT-swift.org> wrote:

> Given an array of instances of a `Hashable` value type, all equal
> according to `Equatable` protocol, but with distinct `hashValue`s, 

Equal hashables must have the same hashValue.  If you violate this rule,
all bets are off.  As the doc says:

  A hash value, provided by a type's hashValue property, is an integer
  that is the same for any two instances that compare equally. That is,
  for two instances a and b of the same type, if a == b then a.hashValue
  == b.hashValue. 



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