ABSTRACT
Afull language implementation usually includes no less than three major parts: the virtual machine, the language libraries, and the tool set. Unless the language is of a very low level and is primitive such as assembly language for
a specic processor, a common language implementation usually includes the core libraries of the language as part of the virtual machine. Sometimes the virtual machine has to hard-code certain logics that only work with the associated libraries. For example, a Java virtual machine (JVM) cannot live without the library package of java.lang, because some of the core data structures such as Java object and Java class rely on the denitions in packages java.lang.Object, java.lang.Class, and so on.
