47 Generic types

Box<T> defines one structure whose item type depends on T. Box<Integer> and Box<String> have different checked field types; value equality still compares contents.

value Box<T> {
  T item
}

main() {
  Box<Integer> count = Box<Integer>(item: 7)
  Box<String> label = Box<String>(item: "Norm")
  printLine(count.item)
  printLine(label.item)
  printLine(count == Box<Integer>(item: 7))
}

Expected output:

7
Norm
true

Try it: Try assigning label.item to an Integer binding.

Precise rules: Reference.