Comment by lispm

I load the Lisp code of a project into the Lisp environment, which is the program and the development environment in one thing. Then all the information about the project is available in the running IDE/program combination. The thing then is fully reflective and introspective.

An example is GNU Emacs itself. For Emacs Lisp it is both the IDE and the application environment.

Similar integrated systems existed already earlier for Lisp and Smalltalk. Interlisp, the MIT Lisp Machine, Smalltalk 80 and others were examples where the IDE and the code was integrated.

OTOH, the combination of GNU Emacs and external Lisps, like Common Lisp systems, was basically LSP before LSP existed. There were tools like ILISP, which connected GNU Emacs to various external Lisp runtimes (which have all the development information about the loaded code). SLIME replaced it at some point in time and usually connected to external Lisps via network connections.