The ability to do interactive development in Common Lisp is something you won't find in basically any language. Smalltalk and Forth are probably the only other

The ability to do interactive development in Common Lisp is something you won't find in basically any language. Smalltalk and Forth are probably the only other languages that have similar capabilities (modern Smalltalk images still have zombie processes and unreachable data from decades ago before the implementations had proper garbage collection). Python REPL can't compare to what CL offers. In CL, I load up a bunch of files and start coding with my codebase running in a REPL. Whenever I make code changes, I can patch in those changes to the running instance. I can try them out instantly. If I've accidentally caused complex conflicts with running code, CL has the tools to deal with them. You can even do this kind of interactive updating against running CL instances (more importantly, you can do interactive debugging against production instances). In Python, you can have a repl open, but there's not a good way to monkey patch everything. Loading all the things is painful. Stuff like adding new libraries to the repo can cause conflicts. If you update just one definition in a file, you must reload everything which makes those complex conflicts more likely, but Python also doesn't have the tools to solve those conflicts. You aren't getting anything interactive unless you are explicitly running your app in a debugger (and doing this in production just isn't going to happen). Another fun thing about Common Lisp is dynamic bindings for some things. It's not strictly necessary, but makes certain things a lot easier where you can configure a variable that updates the variable in the called function(s) rather than having to pass it in every time you call those function(s). Finally, on the macro front, macros are compile time while your Python equivalents are runtime. This is a huge difference when it comes to performance. Python is already dog slow and doing a bunch of dynamic stuff makes that even worse.