Seems like a trollish title, considering people were building stuff in other Lisps for decades and still do.

Also (note that I only went through the slides), it seems like he misunderstands what "All the way down" traditionally means in the context of Lisp. Clojure is different than the lisp variants that embrace this philosophy BECAUSE it's implemented on top of the JVM/CLR. You have access to the core Clojure implemented parts of the language, but you eventually hit a boundary where you explicitly cannot go further -- precisely where the Java part starts.

I guess you could argue that most Schemes / Lisps have a similar boundary, but from using both it feels different in Clojure.

In short, I think you run out of turtles to jump down onto at a certain point in Clojure.

grayrest

Clojurescript is the more "all the way down" of the two. It managed to self-host a few months ago so in theory you could write a backend and cross compile to your computing platform of choice. I know of a number of alternative targets but they all predate the self-hosting and none are actively maintained:

[1] https://github.com/takeoutweight/clojure-scheme [2] https://github.com/raph-amiard/clojurescript-lua

I think it'd be a fun project to get cljs-lua working and build a system for developing OpenResty apps but it's so low on my priority list I don't anticipate ever making it happen.