Remove collection conformances to Equatable and Hashable

[timvermeulen]

Implementing Equatable (and especially Hashable) correctly isn't straightforward for some of the non-trivial collection wrappers in this package, if we consider collections to be equal if they produce the same elements. Here are some examples of comparisons that should evaluate to true, despite the collections having unequal base collections:

[1, 3, 5].striding(by: 1)         == [1, 2, 3, 4, 5].striding(by: 2)
[1, 2].windows(ofCount: 10)       == [1, 2, 3].windows(ofCount: 100)
product([1, 2], "")               == product([1, 2, 3], "")
chain([1, 2], 3..<6)              == chain([1, 2, 3], 4..<6)
[1, 2].combinations(ofCount: 0)   == [1, 2, 3].combinations(ofCount: 0)
[1, 1, 1, 2].uniquePermutations() == [1, 2].uniquePermutations()
[1, 1, 1].cycled(times: 2)        == [1, 1].cycled(times: 3)

Implementing Hashable is often even harder because equal values should produce equal hash values, and therefore every collection needs to hash in the exact same way as all other collections equal to it.

For the moment we're removing all conformances of the sequence and collection types to Equatable and Hashable to avoid any ambiguity on this front, which is consistent with sequence and collection adaptors in the standard library. Most of the time s1.elementsEqual(s2) should be preferred anyway, because it lets you compare sequences that aren't instances of the same type.

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary

[timvermeulen]

@swift-ci please test

[natecook1000]

@swift-ci Please test

[natecook1000]

+2 −209

🎉