Not to mention that many languages written in C use unions to describe their primitive -type- [ed: object]. The result is that the minimum number of bytes for storing an integer for instance, is the minimum number of bytes that can store a value of the largest type.

For example, if you have an string type, which keeps track of it's length, then you might need 8 bytes. 4 for the pointer to the string of chars, 4 for the integer to keep count.

Here's a better example from tinyscheme:

    struct cell {
      unsigned int _flag;
      union {
        struct {
          char   *_svalue;
          int   _length;
        } _string;
        num _number;
        port *_port;
        foreign_func _ff;
        struct {
          struct cell *_car;
          struct cell *_cdr;
        } _cons;
      } _object;
    };

As a minimum, each object takes up max(sizeof(_string), sizeof(num), sizeof(port), sizeof(_cons), sizeof(foreign_func)); And num is defined as follows:

    typedef struct num {
       char is_fixnum;
       union {
          long ivalue;
          double rvalue;
       } value;
    } num;