How to Make Common Lisp go Faster Than C

https://www.lrde.epita.fr/~didier/research/verna.06.imecs.pdf

by smanek • 18 years ago

18 42 18 years ago

lrde.epita.fr

smanek• 18 years ago

Oh, and sorry. I actually submitted a link to the PDF directly, but YCNews scribd it and now it's unreadable. Here is the original:

http://www.lrde.epita.fr/~didier/research/verna.06.imecs.pdf

fff1232• 18 years ago

This is ridiculous. They should change the name back to YC News since they've decided to shill for their own investments.

jcromartie• 18 years ago

This scribd thing is getting ridiculous. Why not make it an opt-out arrangement for submitters?

dpapathanasiou4• 18 years ago

And while they're at it, they could also check for duplicate submissions: http://news.ycombinator.com/item?id=172432

jcl4• 18 years ago

They do check. The sequence of events here seems to be:

- Person submits PDF article.

- HN rewrites article to scribd link.

- People complain about scribd link.

- Admin manually corrects link to point directly to PDF.

- A month later, another person submits same PDF article.

- HN rewrites article to scribd link, but because the original article was manually corrected, the scribd link doesn't match the original article, so it doesn't register as a dupe.

ExplodingBob• 18 years ago

The Scribd file was degraded in quality to absolute illegibility, I had to grab the original link out of the URL just so I could read it.

Opt-out? It's annoying. They should just stop doing it for everyone perhaps, or just use it as a backup in case the site is knocked off line by the influx of social news traffic.

Hexstream2• 18 years ago

"While Lisp is mainly known for its basement on list processing, the Common Lisp standard features very efficient data types such as specialized arrays, structs or hash tables, making lists almost completely obsolete."

Uh?!?

spydez• 18 years ago

No one uses lists in a LISt Processing language. :P

Zak2• 18 years ago

Many of the interesting macros I've seen use list operations heavily to slice and dice their arguments and body code. Most experienced Lispers use macros quite a bit.

jrockway• 18 years ago

Authors of computer science papers aren't exactly known for their command of the finer points of the English language. basement?

sah2• 18 years ago

In languages that can mutate data structures using side-effects, linked lists are rarely the best choice of data structure. Note, for example, that Python and Ruby have built-in array-based lists, but no linked lists. Similar structures are the default for lists in C++, Java, and C#.

That said, I'm pretty sure people use linked lists a lot in Common Lisp.

astine• 18 years ago

Memory usage and random access times are far better in arrays, but for dynamic resizing, deletion, insertion, appending, and splitting, that is, operations that deal with data structure rather than the content, lists are far superior to arrays.

I used to hand-code linked lists back when I used C/C++ heavily. They have some very significant advantages for modeling certain kinds of data.

cheponis• 18 years ago

We can hack around the scribd censorship. Everybody who aubmits a .pdf knows it will be converted into the useless scribd format. So, the original submitter needs to immediately post a comment that is the original .pdf link.

If HN scribd damage occurs on that link, then we will find other ways to route around that damage, for example, by using tinyurl.

Down with scribd!!!

dbrush2• 18 years ago

.pdf != HD-DVD key

Hacker News != Digg

jmatt2• 18 years ago

tinyurl is a great idea too.

jmatt2• 18 years ago

http://www.lrde.epita.fr/~didier/research/verna.06.imecs.pdf

There is an easy work around for this. Submit the pdf link. Then comment with the pdf link. That adds one level of indirection, until pg gets around to fixing it.

This is hacker news, So I'm assuming people can use their browser and copy and paste.

  1) copy link location.
  2) paste link location in address bar.
  2) remove scribd.com crap, leaving the original pdf link.
  3) load original pdf link.

gibsonf14• 18 years ago

My co-founder tried out some of the techniques in the paper on our system: "I was skeptical, probably because I've never done much performance tuning like this. But I changed (triples) to create a 2-d array of fixnums instead of the default list of lists from the select. I added the declarations. It's about 100x faster. 100!" Very nice :)

mark-t• 18 years ago

How did this comment end up in the rss feed?

Interestingly, the "comments" link for it points to http://news.ycombinator.com/item?id=196342 -- the original post without any comments shown!

ambition• 18 years ago

It was submitted as a standalone post. There are no comments on the new submission.

xirium3• 18 years ago

When I mentioned that it may be possible for a web startup in beta to improve the speed of their code by a factor of 1024 over no particular timescale, I was downmodded by five points ( http://news.ycombinator.com/item?id=187692 ).

I can only advise that you shouldn't quit while you're ahead. Now that you've eliminated the most obvious performance bottlenecks, you may find that less obvious bottlenecks have emerged. Removing these could give you an additional factor of 10 improvement.

scott_s2• 18 years ago

Probably not. Remember Amdah's Law: http://en.wikipedia.org/wiki/Ahmdal%27s_Law

gibsonf14• 18 years ago

We're using the SBCL profiler on a regular basis to speed up the system whenever we find an area that feels a bit sluggish. We've made very large speed gains with only minor coding modifications.

michael_dorfman• 18 years ago

Premature optimization may be the root of all evil, but failure to optimize isn't too hot either.

Glad to hear your results were so dramatic.

gibsonf14• 18 years ago

We only optimize when things start feeling a bit slow - never prematurely.

How to Make Common Lisp go Faster Than C

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