Could you say a bit more about your workflow? I'm used to having source code files open in emacs (or zemacs) and a lisp REPL in another buffer. I edit the source files directly and then recompile changes into the running lisp. The code stays in sync because the text code files are the master copy and the running image is updated (when I choose) to reflect changes. Program state (e.g., large data structures) isn't generally kept in the source files. If what's in memory needs to be preserved, then I need to have serialization and deserialization methods, or a database, or I need to save the running image to a snapshot file. I've probably so internalized this process that there are problems with it that are invisible to me.