Почему механизм copy-on-write не применяется к типу Int в языке программирования?

The copy-on-write (COW) mechanism is applied to types that are reference types or contain large amounts of data to avoid unnecessary copying during passing and modification. The Int type in Swift is a simple, primitive value type with a fixed size (usually 64 bits), which is copied very quickly and efficiently. Therefore, applying COW to Int does not make sense, as the overhead of managing copying would outweigh the benefit. COW is useful for complex data structures where copying is expensive.