Checklist

• All tests are passed.
• Added tests.
• Documented the code using Xcode markup.
• Searched existing pull requests for ensure not duplicated.

Description

The default implementation of Differentiabe for Hashable has a differenceIdentifier property. The implementation of this propeprty now return hashValue instead of self.

Related Issue

// Model
struct ElementModel: Hashable, Differentiable {
    var id: Int
    var title: String
    var value: String

    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
    }
}

// Changeset
let list1 = [ElementModel(id: 1, title: "color", value: "red")]
let list2 = [ElementModel(id: 1, title: "color", value: "blue")]

let changeset = StagedChangeset(source: list1, target: list2)
changeset.forEach { print($0) } // two stage: `delete` -> `insert`

The above code produces a delete -> insert change, however, it should be a update change.

#114: Unexpected behavior when using the default implementations of Differentiable for Hashable

Motivation and Context

Close #114

Impact on Existing Code

If the existing code rely on the default implementation of Differentiable for Hashable, the reload behavior may changes. Some delete -> insert changes will become update changes.