Condition Systems in an Exceptional Language - Chris Houser

ClojureTV · 15.9K views · 2015-11-17 · 33:32

Open on YouTube ↗

If playback is restricted in your region, try opening the original video. Use Mark watched to add it to your marked videos.

Overview

Chris Houser's Clojure/conj talk on why Clojure's exceptions destroy information as the stack unwinds, unlike Common Lisp's condition system, which can resume from the error site. He surveys the existing libraries that approximate conditions, explains why they don't compose with each other, and considers what a better design would look like.

On Hacker News

Clojure commenters cite it as the best overview of condition systems in Clojure and of the libraries that attempt them.

Recommended by 1 HN people across 1 months · HN mentions 2016–2022

Topics

Functional programming Programming language design

What people said

puredanger · 2017-02 · Recommendation
There are some libraries for this. A great overview of the problem and some of the libs is [VIDEO] and a good set of corresponding notes at [LINK]
Read the original HN comment ↗

the-alchemist · 2022-09 · Reference
True, the CL REPL is more useful than the Clojure REPL, but CL has a 20-30 year head start in development. Plus, Clojure was developed as a hosted language, and runs on .NET, Javascript, JVM, and even Dart (in-progress). Since exceptions are quite deeply integrated into those platforms (as opposed to conditions), it has "bled through" to the Clojure APIs, and, in turn, REPL. Folks have written a CL-style condition/restart library for Clojure ( [LINK] ) too. [VIDEO] video too.
Read the original HN comment ↗

phyrex · 2018-12 · Reference
You can do that yourself if you care ( [VIDEO] ) but I get what you mean. On the other hand, on a server application a REPL on exception wouldn’t help me.
Read the original HN comment ↗

Sources

Video by ClojureTV, played through YouTube.

HN Library · Source license

Data and selection notes

HN summaries and labels may contain AI errors. HN dates refer to discussions, not video publication.

HN Library: HackerTube export (2026-10-31) and open-index/hacker-news. Upstream summaries and classifications may contain AI errors.

Views, duration and playback status refresh separately from the published catalog. When an update fails, existing data remains visible.

Selection checks

SaaS & AI candidates: Topic keywords do not match
Editor-approved picks: Editorial review is required

Rule matches identify candidates. They do not guarantee video quality or financial results.

About the library and its sources