SaddledBounding

    person = Person {_name = "Alice", _title = "Dr"}

    -- get field with magic lens
    person ^. title == "Dr"

    -- create new object with new field value
    person & name .~ "Bob"
        == person & (name .~ "Bob")
        == (name .~ "Bob") person
        == Person {_name = "Bob", _title = "Dr"}

    -- create new object with function applied to field value
    person & name %~ lowercase
        == (name %~ lowercase) person
        == Person {_name = "alice", _title = "Dr"}

    utf-8 decode
      switch (std::countl_one(unit)) {
        case 0:
          /* one unit */
          break;
        case 2:
          /* two units */
          break;
        case 3:
          /* three units */
          break;
        case 4:
          /* four units */
          break;
        default:
          /* not code point boundary */
          break;
      }