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> how many years of your career you have spent in embedded systems

Depends on how you count, but probably about 20. 15 of those were at NASA. Gerard Holzman (the author of the paper we're discussing) was in the office next to mine for about 3 years. Oh, and Common Lisp code that I wrote actually controlled a spacecraft back in 1999.

https://ti.arc.nasa.gov/tech/asr/planning-and-scheduling/rem...

Does that qualify me to talk about these things?



> Does that qualify me to talk about these things?

Yes, certainly. (Though I have been in embedded longer - 25 years. But you've been in safety-critical longer than me.) I must admit that I under-rated your experience.

What part of the stuff from that link was written in Lisp? Was it just the planner, or also the exec? That is, did it have to be real time?

And, in my previous reply, I asked a bunch of questions (besides the ones about whether you knew what you were talking about). Would you answer them?


> What part of the stuff from that link was written in Lisp?

All of it. (Except for an IPC system which was written in C. See https://www.youtube.com/watch?v=_gZK0tW8EhQ if you want to know the whole story.)

> Would you answer them?

I'll answer a few of them.

> if Lisp is so wonderful compared to C, how come so many more safety-critical systems are written in C?

Politics mainly. And inertia. And the sunk cost fallacy.

> Is it because the entire profession is blind, and only you and a few enlightened ones realize how wonderful Lisp is?

Yes. Pretty much.

> Or is it because people that have done this for decades see more problems with Lisp than you are aware of?

They, like you, think they see problems, but they, like you, are wrong.

Tellingly, none of the people who think there are problems with Lisp actually know Lisp.


> Politics mainly. And inertia. And the sunk cost fallacy.

I would say no, sort of, and maybe. I don't think I've ever seen a language chosen because of politics. For "inertia", I would say "conservatism" - people know that they can build systems (even safety critical ones) using C, and they know where the problems are. They don't know where the problems are using Lisp. And they don't want to take the time to learn Lisp - that's sunk cost, but whether it's a fallacy or not depends on whether Lisp really is more suited for such work than C. You assert that it is; many of us would like to see considerably more evidence before we agree.

What evidence? Maybe a few hundred hard real time systems successfully written in Lisp. (But how are we going to get them, if everybody defaults to C? I will grant you that there's a chicken-and-egg problem here...)

> > Is it because the entire profession is blind, and only you and a few enlightened ones realize how wonderful Lisp is?

> Yes. Pretty much.

Yeah... um... I think I'll just let your words speak for themselves.


> chicken-and-egg

Yep.


I want to follow up that whole discussion by stating I really appreciate someone with actual experience in this area chiming in. NASA code attracts a huge amount of bikeshedding here.


Thanks!




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