Expired SSL Certificate

Posted on 2019-12-13 by jcs

I noticed this morning that Irreal’s SSL certificate expired last night. I’ve ordered a new one that should be active shortly (although it was a hassle last time so who knows). In the mean time you can still reach the site using the HTTP (rather than the HTTPS) URL.

Posted in Administrivia | Tagged | Leave a comment

Building a Personal Knowledge Base

Posted on 2019-12-12 by jcs

I’m a big believer in collecting and storing information: in building a personal knowledge base if you like. I do this, of course, with Org-mode but that’s not the only possibility. Sung Cho has a nice post in which he describes how he built himself a personal knowledge base.

He started out by keeping his notes in Evernote but soon realized that he was spending all his time maintaining and polishing his notes but hardly ever using them. That led him to his first principal: Organizing knowledge should never become the goal. Rather, the goal should be to retain knowledge and help yourself learn. In keeping with this, he built himself a simple command line interface to a YAML database. He limited each note to a single line and didn’t use any tags.

In accordance with his second principal—searching is more efficient than organizing—he retrieved information by simply grepping for it. That was easy because of the third principal that the knowledge base should be local and open source. At this stage it was also plain text so the powerful Unix search tools could easily be applied for searching.

Overtime he has evolved his system to use an SQL database and made it accessible over the Internet. He also arranged for it to email him a digest of his recent entries to help him absorb the material. The whole system is open source and you can download a binary or source code from the dnote repository.

My own system pretty much adheres to Cho’s principals but I do use tags to help me search the data. I don’t obsess over them: I just tag the entries with keywords that I think suggest the data I’m entering.

Ali Abdaal has a similar system but he uses the proprietary Notion application and therefore violates the important rule that you must maintain control of your data and the means to access it. Abdaal has an excellent video on his system. It would be pretty easy to implement almost all of it with Org-mode so the video is worth watching even if you’re not interested in Notion.

Posted in General | Tagged , , | Leave a comment

Keeping An Open Access Site Online

Posted on 2019-12-11 by jcs

I’ve written several times about the renegade pirate sites that curate scientific papers and make them available for free (1, 2, 3, 4, 5, 6). Their actions are clearly illegal and some say immoral but they’re a useful corrective to the equally immoral and predatory behavior of the scientific journal publishers. All of my previous posts have focused on Sci-Hub but it turns out there is another site, Library Genesis (LibGen), that has over 33 terabytes of books, papers, and other material available. Together, the two sites ensure the availability of the papers that researchers without access to University journal subscriptions need for their research.

The publishers and their governments are not amused and have done everything they can to shut these sites down but the open access movement is fighting back. A project started by redditors is seeking to make sure that LibGen is never again offline. That’s a substantial undertaking because in addition to suing the two sites, the publishers have fought to have the sites’ hosting shutdown or blocked. Read the Vice article linked above to see what the redditors are doing to keep LibGen online.

As I’ve said before, it’s easy to be conflicted about all of this. There’s no doubt that Sci-Hub and LibGen are stealing the papers but there’s also no doubt that the publishers are predatory rent seekers who abuse the original authors, the reviewers, the schools, their subscribers and even their own editorial staffs who are mostly unpaid university volunteers. In the end, the universities themselves will probably solve this problem by refusing, as the University of California has, to renew their subscriptions unless the publishers change their business models.

Posted in General | Tagged | Leave a comment

How to Alias Car and Cdr and Why You Probably Shouldn’t

Posted on 2019-12-10 by jcs

A couple of days ago, I wrote about the minor controversy concerning the names of the Lisp functions car and cdr. Some people, mostly non-Lispers but also some who use Lisp, dislike the names and think they should be changed to something more mnemonic like head and tail or first and last. Paul Graham disagrees and tweeted an excellent, pithy argument as to why. I agreed with Graham and the post was really about his tweet.

Of course, being Lisp, it’s easy to alias the names to whatever you like. However, there is, at least for Emacs, a practical reason that you shouldn’t do that or at least that you should know what you’re doing before you try. Chris Wellons, who has a profound understanding of Emacs and Emacs Lisp has a very enlightening post as to why adding something like

(defalias 'head #'car)

to your init.el file is a bad idea. The reason for that is that Emacs Lisp recognizes the importance of car and cdr and has special byte code operators for them. When you alias car to something like head, the optimizer can no longer be sure that the meaning won’t change and therefore turns the head reference into a function call. Wellons has the details but the TL;DR is that the result runs twice as slowly.

This is Emacs so it is, of course, possible to do the alias and still have the result use the car byte code but you have to tell the optimizer explicitly to do so. Again, see Wellons’ post for the details.

Wellons’ post is a slight expansion of his comment to the reddit post asking how to alias car that I referenced in my original post. His explanation is generally useful, though, so I’m glad he made it a separate post.

Posted in General | Tagged | Leave a comment

How To Wrap The MacBook Power Cord

Posted on 2019-12-09 by jcs

While learning how to pour organge juice, I stumbled on a video that shows you the right way to wrap your MacBook power cord into a small neat package that fits easily in your backpack:

Here’s another video that shows the same technique but emphasizes taking the strain off the cable so that it doesn’t fray prematurely.

Posted in General | Tagged , | Leave a comment

Car and Cdr versus Head and Tail

Posted on 2019-12-08 by jcs

Right after parentheses, one of the things about Lisp that non-Lispers—and even some Lispers—like to complain about are the names of the two functions car and cdr. A common understanding is that car returns the first entry of a list and cdr returns everything after the first entry but they’re more accurately thought of as returning the contents pointed at by the first and second halves of a cons cell. That view helps us understand where the names come from.

The names are an historical artifact from the first implementation of Lisp and refer to a pair of assembly language macros used to access the two halves of the IBM 704 CPU registers. When a cons cell was in a register, the car macro would access the first half of the cell and the cdr macro would access the second half. Some Lispers have sought to replace these, admittedly opaque, names with something more intuitive and obvious such as head and tail or first and rest. Many have resisted these efforts, finding car and cdr short and perfectly adequate. Paul Graham makes a cogent argument for the traditionalists’ view:

I learned Lisp by reading Graham’s books so my thinking on Lisp matters is often informed by his but that aside, I agree with his tweet completely. It makes a convincing case for using car and cdr.

This discussion applies to Elisp too, of course, so Emacsers asking how they can alias car and cdr to head and tail should consider Graham’s argument carefully.

Posted in General | Tagged , , | Leave a comment

BPF: A New Type of Software

Posted on 2019-12-07 by jcs

When I first saw the title of Brendan Gregg’s blog post—reproduced above—I had a small frisson of annoyance. BPF (aka Berkeley Packet Filter) has been around since 1992 as the kernel interface to tcpdump and here was Gregg appropriating the name for some other piece of software. I needn’t have worried. Gregg was, in fact, talking about the Berkeley Packet Filter but in its extended form as implemented in the Linux kernel. Actually, it’s been extended so much that it no longer has much to do with Berkeley, packets, or filtering. It implements a fairly powerful virtual machine that runs in the kernel.

Gregg recently gave a talk on BPF for the Ubuntu Masters Conference in which he describes the (extended) system and why it’s a new type of software. Rather than being a user application or kernel module, applications written for BPF run in user space but have access to kernel facilities through a special BPF API. There are many advantages to this approach including ease of implementation and safety.

Gregg works for Netflix and mostly uses BPF to instrument the kernel. He describes several examples in the talk that illustrates some of the things one can do with it. The system is a little complicated so your best bet is to watch the video for the details. If you’re really interested, Gregg has a book (out as an ebook, coming this month as a dead tree book) that describes the system in detail. It’s an interesting talk and definitely worth watching. Gregg’s post at the above link also has a pointer to the talk’s slides. The video is about 31 minutes so you’ll need to schedule some time.

Update added before publishing
ZDNet has an article on BPF and Gregg’s talk. If you’re interested in this technology, it’s worth reading after you watch the video.

Posted in General | Tagged | Leave a comment

Techie Luddites

Posted on 2019-12-06 by jcs

Those of you who have been around Irreal for a while know that one of my favorite hobby horses is the new luddites. These are mostly humorless folks who imagine that the rest of us share their psychoses and who, therefore, think it their duty to instruct us on the proper way of doing things. One of their most recent obsessions is with “tech addiction” and why we should all throw out our smartphones.

It’s easy to think of these people as some sort of Amish-like sect but that would be a calumny on the Amish. In truth, the new luddites can be found in almost any demographic. Even ours. In an interesting article in the Los Angeles Review of Books, Morgan G. Ames tells us how many of the “technical elite” refuse to let their children use electronic devices such as phones, tablets, or computers and how they send them to schools that proclaim themselves to be traditional and tech-free.

As Ames points out, many of these technical people consider themselves to be the smartest people in the room and while that may be true regarding technology, they don’t know anymore than the rest of us about child development or the wider social implications of technology. They are, in fact, subject to the same fashions and misinformation as everyone else.

If that claim seems a little overwrought, consider this shocking fact: at the Waldorf School of the Peninsula, “[a] techie-dominated, tech-shunning school,” only 35% of kindergarteners had been fully vaccinated before California made such vaccinations mandatory. If even the anti-vaxxers have established a beachhead among the technical elite, we must certainly abandon any claim to being immune to new luddism.

Ames is a former CS graduate who gave up the field to pursue a PhD in Communications and the article sometimes seems as if she’s trying a bit too hard to disparage her former brethren but she makes many good points and the article is worth reading.

Posted in General | Tagged | Leave a comment

The Myth of the Young Entrepreneur

Posted on 2019-12-05 by jcs

One of geekdom’s most cherished beliefs—especially among young hackers—is that of the 20 year old who comes up with a new idea, builds it into a fabulously successful business, sells it for millions after a few years, and retires a millionaire at age 27. Indeed, Paul Graham built his own business catering to that idea and has helped start several successful companies.

It turns out, though, that our cherished belief is mostly a myth, at least according to a study by Pierre Azoulay, Benjamin F. Jones, J. Daniel Kim, and Javier Miranda. An article on the American Institute for Economic Research (AIER) Website discusses the study and some of its conclusions. The TL;DR is that experience, domain knowledge, and discipline are actually the best predictors of startup success and that most successful startup founders are middle aged (mean of 45 years old for the 1 in 1,000 highest growth new ventures) rather than the 20 year old who drops out of school to follow his dreams.

That’s a provocative claim that goes against the conventional wisdom but the study authors took a hard look at the data and are reporting what they saw. I’m not an economist so I can’t speak to the validity of the study but it does seem well researched and is certainly worth looking at if you have the itch to start your own company. There are, of course, many examples of young hackers who have built successful companies but it’s hard to name more than a handful. Doubtlessly, Graham could name more than most of us but of the thousands of companies he helped launch how many could be termed huge successes? The data the study presents (and which is discussed in the AIER article) is pretty discouraging for young entrepreneurs.

Posted in General | Tagged | Leave a comment

Org 9.3

Posted on 2019-12-04 by jcs

Bastien Guerry has announced the release of Org-mode 9.3

In the tweet and the original announcement, Guerry emphasizes that this is a major release with some incompatible changes so you should read the Change Log.

As usual, thanks to Nicolas and Bastien and the others for all their hard work. The Org community is lucky to have such a great development team.

Posted in General | Tagged , | Leave a comment