One More Thing

Dan Creswell writes...

the last thing to do is to extend the language

He's speaking about Java in particular but it could apply to all kinds of languages that were never intended for much extension.

Do you want extension? Use Lisp, or Ruby, or Smalltalk. They've proven themselves very well for extensions to one degree or another. Certainly Lisp.

Otherwise choose a reasonable language(s) and use them. Don't pile more stuff on them than they can bear.