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The CDR Fell Off

2022-04-29

Last month my former colleague, Chouser, invited us to work through Lisp in Small Pieces (LiSP) as a group. Forty-six of us joined the group slack and are working through Chapter 1 exercises right now. Allegedly.

Amazon says LiSP landed in my wish list mid-2015, so it’s high time I checked this one off. Coincidentally, 2015 is the last I worked on the LonoCloud team and wrote Clojure for a day job.

I’m porting the book’s code to Clojure and thoroughly enjoying this stack again. New-to-me friends include the new-as-of 2017 tools.deps and CLI and Hyperfiddle’s RCF for executing Rich Comment Blocks as tests.

More on that in my next post, but for now, something silly.

Reading LiSP 1.7 Global Environment, I remembered the famous Clarke and Dawe sketch “The Front Fell Off”.

The environment’s perfectly safe!

So with my apologies to the comedic duo, and fond remembrance of the late John Clarke, I give you “The CDR Fell Off”.


Senator Collins: It’s a great pleasure, thank you.

Interviewer: This list that was involved in the incident in ap-southeast-2 this week…

Senator Collins: Yeah, the one the CDR fell off?

Interviewer: Yeah.

Senator Collins: That’s not very typical, I’d like to make that point.

Interviewer: Well, how is it untypical?

Senator Collins: Well, there are a lot of these lists going around the world all the time, and very seldom does anything like this happen … I just don’t want people thinking that lists aren’t safe.

Interviewer: Was this list safe?

Senator Collins: Well I was thinking more about the other ones…

Interviewer: The ones that are safe?

Senator Collins: Yeah. The ones the CDR doesn’t fall off.

Interviewer: Well, if this wasn’t safe, why did it have 80GiB of memory in it?

Senator Collins: Well, I’m not saying it wasn’t safe, it’s just perhaps not quite as safe as some of the other ones.

Interviewer: Why?

Senator Collins: Well, some of them are built so the CDR doesn’t fall off at all.

Interviewer: Wasn’t this built so the CDR wouldn’t fall off?

Senator Collins: Well, obviously not.

Interviewer: “How do you know?”

Senator Collins: Well, ‘cause the CDR fell off, and 80GiB of memory leaked, and got OOM killed. It’s a bit of a give-away. I would just like to make the point that that is not normal!

Interviewer: Well, what sort of standards are these lists built to?

Senator Collins: Oh, very rigorous … software engineering standards.

Interviewer: What sort of requirements?

Senator Collins: Well the CDR’s not supposed to fall off, for a start.

Interviewer: And what others?

Senator Collins: Well, there are … regulations governing the software development process.

Interviewer: What processes?

Senator Collins: Well, YOLO’s out.

Interviewer: And?

Senator Collins: …No YOLO derivatives…

Interviewer: Like Scrum?

Senator Collins:. … No Scrum, no YOLO, no XP. …

Interviewer: Agile?

Senator Collins: No, Agile’s out … Um, They’ve got to have a product manager. There’s a minimum team size.

Interviewer: What’s the minimum team?

Senator Collins: Oh … one, I suppose.

Interviewer: So, the allegations that they are just designed to carry as much memory as possible and to hell with the consequences, I mean that’s ludicrous…

Senator Collins: Ludicrous, absolutely ludicrous! These are very, very strong lists.

Interviewer: So what happened in this case?

Senator Collins: Well, the CDR fell off in this case by all means, but that’s very unusual.

Interviewer: But Senator Collins, why did the CDR bit fall off?

Senator Collins: Well, an application hit it.

Interviewer: An application hit it?

Senator Collins: An application hit the list.

Interviewer: Is that unusual?

Senator Collins: Oh, yeah… In a Lisp? …Chance in a million.

Interviewer: So what do you do to protect the environment in cases like this?

Senator Collins: Well, the list was defined outside the environment.

Interviewer: Into another environment?

Senator Collins: No, no, no. it’s been defined beyond the environment, it’s not in the environment

Interviewer: Yeah, but from one environment to another environment?

Senator Collins: No, it’s beyond the environment, it’s not in an environment. It has been defined beyond the environment.

Interviewer: Well, what’s out there?

Senator Collins: Nothing’s out there.

Interviewer: Well there must be something out there

Senator Collins: There is nothing out there… all there is … is C …and BASIC … and JPL

Interviewer: And?

Senator Collins: And 80GiB of leaked memory

Interviewer: And what else?

Senator Collins: And an OOM kill.

Interviewer: And anything else?

Senator Collins: And the part of the list that the CDR off, but there’s nothing else out there.

Interviewer: Senator Collins thanks for joining us.

Senator Collins: It’s a complete void.

Interviewer: Yeah, We’re out of time

Senator Collins: The environment’s perfectly safe. We’re out of time? Can you book me a cab?

Interviewer: But didn’t you come in a commonwealth CAR?

Senator Collins: Yes, I did, but …

Interviewer: What happened?

Senator Collins: The CDR fell off.

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