AnyEquatable.swift

import Foundation

struct AnyEquatable {
    private let isEqualTo: (Any) -> Bool
    let value: Any
    
    init<A: Equatable>(_ value: A) {
        self.value = value
        isEqualTo = { other in
            guard let o = other as? A else { return false }
            return value == o
        }
    }
}

extension AnyEquatable: Equatable {
    static func ==(lhs: AnyEquatable, rhs: AnyEquatable) -> Bool {
        return lhs.isEqualTo(rhs.value)
    }
}

let x = AnyEquatable(5)
let y = AnyEquatable("hello")
x == y

AnyEquatable(4) == AnyEquatable(4)