ECL is of course Embeddable Common Lisp, a small but quite complete Common Lisp implementation that can be easily embedded in your C applications to act as dynamic extension language, but it is also a fine stand-alone implementation. It includes an interpreter and a compiler, and can even produce compact binaries. Read this blog post by Chris Kohlhepp for a brief and practical overview. SLIME is the Superior Lisp Interaction Mode for Emacs, a great Emacs environment within which one can write...