Here you will find some screenshots of some of today's web applications built in CL: http://lisp-screenshots.org/ and here an opinionated tutorial: https://web-apps-in-lisp.github.io/ One example: ScreenShotBot https://screenshotbot.io/ a successful open-source product and company. It now replaced Facebook's automatic screenshot testing tool (source: their blog). So, web apps in Lisp are possible -with a right amount of learning time and elbow grease.

The incremental development and interactive top-level are still precious and unmatched.

It was one of those things where 1-3 programmers, working with the right tools and thinking, could out-perform all competitors, no matter how much resources competitors threw at the problems. (I can't take credit for the initial architecture and implementation: that was all someone else.)

The system actually outlived Viaweb by decades, and I suspect still uses Scheme for a lot, especially for the necessarily complex backend.

(Half the problem for Scheme uptake was that most students only saw it school, as presented by a CS professor in an intro class, and then they did annoying homework, so they hoped never to use it again. They should've seen what we did with it, making it fly in ways that a CS professor wouldn't in first-year classes, compared to how it would've been done in other languages at the time.)

> One way we used macros was to generate Html. There is a very natural fit between macros and Html, because Html is a prefix notation like Lisp, and Html is recursive like Lisp. So we had macro calls within macro calls, generating the most complicated Html, and it was all still very manageable.

We just used lists and functions for HTML. And often with quasiquote, when we wanted to splice "dynamic" bits into a substantial chunk of "static".

I didn't try to use macros for HTML until a decade after this talk. I liked the simple DSL, and leaning on buffered I/O ports and string ports, but nobody else seemed to like it as much as I did (maybe because they didn't have a prolific colleague doing 10x code-writing in a rather more delicate way of generating HTML):

https://www.neilvandyke.org/racket/html-template/

(Don't look at the code, though. I wrote it before Racket got submodules, which are great if you have a strict, non-CL-ish module system and syntax extension mechanism that otherwise make some things much harder than in CL. I have a TODO note in there to refactor it with submodules, but I had to redirect my time towards other languages, for reasons having nothing to do with language merit.)

The disadvantage of this kind of stateless server is that you need to keep around a hash full of continuations, basically one for every page visit. Each of these continuations contains an entire environment and stack, and you have to manage all that memory allocation somehow. You need to serialize the continuations in order to cache them. Then you need to figure out which ones to keep around.

Authentication is potentially also an issue because absent some other security mechanism, anyone who knows the hash of the continuation can visit the page with the same permissions as the original user. https://docs.racket-lang.org/web-server/faq.html (10.7)

Apparently this website runs on LISP so I would be interested to know how it works under the hood. For me, anything more than a SPA seemed like too much pain.

> Rtml even depended heavily on keyword parameters, which up to that time I had always considered one of the more dubious features of Common Lisp. Because of the way Web-based software gets released, you have to design the software so that it's easy to change. And Rtml itself had to be easy to change, just like any other part of the software. Most of the operators in Rtml were designed to take keyword parameters, and what a help that turned out to be. If I wanted to add another dimension to the behavior of one of the operators, I could just add a new keyword parameter, and everyone's existing templates would continue to work. A few of the Rtml operators didn't take keyword parameters, because I didn't think I'd ever need to change them, and almost every one I ended up kicking myself about later. If I could go back and start over from scratch, one of the things I'd change would be that I'd make every Rtml operator take keyword parameters.

https://blog.cloudflare.com/topaz-policy-engine-design/