jasonofthel33t
3 HN recommenders · recommended in 5 months, 2014–2025
53:56 · 119K views · Mar 12, 2013
A Channel 9 Going Deep interview in which Brian Beckman talks with Rich Hickey, creator of Clojure, about the language's design. It covers Clojure's persistent data structures, reference types and its approach to concurrency on the JVM.
HN commenters call it a fantastic introduction to Clojure and the thinking behind its design.
5 comments from Hacker News
Um, destructuring is a very old concept in Lisp circles. [LINK] Don't know if Rich first got the idea from Lisp or not, but it seems likely since he did a bunch of development in Common Lisp (generating C++, of all things :-D ) ages ago. I don't remember if I heard him talk about that in the "Expert to Expert" video ( this video ), or in "Simple Made Easy" ( [LINK] ). I think it was the former, but both of those are worth watching multiple times. It's also entirely possible that it was in an entirely different video of his -- but it was him . I've yet to be disappointed in any of his talks, so if I'm wrong about the exact one, just keep watching any of his talks on YouTube till you find it. xD
I'd like to learn Clojure. Any suggestions on how to get started? It's my first time using a Lisp dialect. I figured I'd tackle the Clojure Koans, and mix in a few Project Euler problems. I'd also like to do some code reading. I know the Clojure source code is on GitHub, but maybe something smaller to start? If anyone else is interested in getting started, here are a few links I visited over the weekend: [LINK] [LINK] [LINK] this video The last link is an hour-long interview with Rich Hickey - a fantastic introduction to the language and his design goals. It's probably the best technical video I've ever watched on YouTube.
> What I don’t understand the advantage for “state management”. Like, you build a new state object, and then mutate some pointer from prevState to nextState… that’s what everyone else is doing too. Clojure's real super power is its reference type(s) (in particular the atom). Rich does an excellent job explaining them in this video: this video
I'm not sure how it's implemented in Ferret but Clojure's data structures are implemented as trees so there's structural sharing that happens when a vector or hash map is updated or when a new version is produced. So the whole data structure isn't copied but only the relevant parts are added / updated in the tree and the rest is shared with the "new" data structure. Mutable data structures are still more memory effective but I'm assuming its fine since the author has a blog post on using ferret on an Arduino Uno which has 32k of ram. [LINK] Clojure data Sturucture links: Persistent Vectors [LINK] Video with Rick hick on them this video
The actual details of how the underlying datastructures work isn't that hard to grasp (see: this video ), but in practice you don't even need to go that far. At a high level there's really just a few things you need to keep in mind, the biggest being the big O guarantees of the core DS interfaces, which are listed here [LINK] . Those guarantees hold across the different underlying implementations, and there are plenty of things you can tune to get a 2x, 10x, 50x improvement in performance before resorting to things that depend on which specific DS is being used under the hood Edit: Fixed timestamp for video link