NilMaxInteger.swift

struct NilMaxInteger<Base: FixedWidthInteger>: RawRepresentable, ExpressibleByNilLiteral {
    var rawValue: Base
    init(rawValue: Base) {
        self.rawValue = rawValue
    }
    
    init(_ value: Base?) {
        assert(value != .max)
        self.init(rawValue: value ?? .max)
    }
    
    init(nilLiteral: ()) {
        self.init(rawValue: .max)
    }
    
    var optionalValue: Base? {
        get {
            rawValue == .max ? nil : rawValue
        }
        set {
            self = .init(newValue)
        }
    }
}