Given an array of instances of a `Hashable` value type, all equal
according to `Equatable` protocol, but with distinct `hashValue`s, I
would expect that initialising a set with that array would preserve all
the instances. Instead, running the code below in an iOS playground on
Xcode 8.0 (8A218a), results in a behaviour that I cannot explain. If
anyone can, I’d be very grateful!
struct X: Hashable {
let x: Int
let hashValue: Int
static func == (lhs: X, rhs: X) -> Bool {
return lhs.x == rhs.x
}
}
let array: [X] = (1...100).map{ X(x: 7, hashValue: $0) } // unique
hash values
array.count //→ 100
let set = Set(array)
set.count //→ 43
let set2 = Set(Array(set))
set2.count //→ 30
let set3 = Set(Array(set2))
set3.count //→ 30
set3.sorted{ $0.hashValue < $1.hashValue }
.forEach{ print(String($0.hashValue, radix: 2), "=",
$0.hashValue) } /*→
1 = 1
11 = 3
101 = 5
1111 = 15
10010 = 18
10011 = 19
11000 = 24
11101 = 29
11111 = 31
100000 = 32
100011 = 35
100100 = 36
100110 = 38
101000 = 40
101001 = 41
101011 = 43
101111 = 47
110010 = 50
110101 = 53
111101 = 61
1000010 = 66
1001011 = 75
1001101 = 77
1001111 = 79
1010000 = 80
1011001 = 89
1011100 = 92
1011110 = 94
1011111 = 95
1100010 = 98
*/
Many thanks,
milos
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