Item — HN Reader

You need to understand the basic principles of how Lisp REPL operates. Simple example - if you're building a web scraper in Clojure, you can connect to the browser and "poke" through elements interactively, without reloading, without compiling, without losing the state.

Now imagine the same principle works with backend services, e.g. we've enabled nrepl endpoint in our staging k8s service, we can modify the behavior dynamically, like adding a new route, for that we'd just need to connect to the REPL, write something like `(POST "/v1/new-effing-route" request ...`, eval it and voila. We don't have to re-deploy, recompile, even save that code - it would just work, like magic.

Now imagine giving this ability to an LLM. It won't have to guess, it won't have to go into write/compile/run/restore-the-state/try loop - it knows what's available, what can affect the behavior of the system, etc. It works surprisingly well and saves tons of time and tokens. Kids who have not tried that, have zero idea how great that is.

1 comments

You explained the magic behind this better than I ever could. But hey, I'm one of the nuschool kids on this, and we want this great language to breach escape velocity too!

Ah, well, "magic" probably not the best word here, to be honest. I find Clojure to be the absolute opposite of witchcraft - everything is pretty transparent, there's no magic encapsulated behind layers and layers of abstraction. Data is just data. Functions do what they say. The macro system is explicit. The REPL makes every intermediate step inspectable.

The irony is that Lisp looks cryptic to newcomers precisely because there's almost zero syntactic sugar hiding the structure. Once you adjust, you realize the "weird syntax" is actually the absence of magic - it's the parse tree, exposed directly. Alas, people prefer sugar flavored lies instead of "inconvenient" truth. I was pretty much the same - wasted years of my life, circling around shit that was all about "magic". At some point, your mind just can't take it anymore - it wants "plain & stupid". Because when shit just works - it doesn't feel that stupid anymore.