Another interesting example of a program like this is CLPython:<p><a href="http://github.com/franzinc/cl-python" rel="nofollow">http://github.com/franzinc/cl-python</a><p>It is too bad that more language implementors do not go this route, as it is a really easy way to get decent efficiency.<p>I suppose it isn't surprising, however. It is a lot easier to find people willing to contribute to open source C/C++/Java code than Common Lisp.<p>I will note this implementation and does not have a lot of the important functionality involved in classes/modules and their scoping (so pretty much any of the language semantics, which is understandable as it is a toy).<p>Implementing the semantics of the language, would be trickier and probably lead to less efficient code.