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kottke.org posts about programming

The Brilliant Life of Ada Lovelace

posted by Jason Kottke   Dec 09, 2016

From Feminist Frequency, a quick video biography of Ada Lovelace, which talks about the importance of her contribution to computing.

A mathematical genius and pioneer of computer science, Ada Lovelace was not only the created the very first computer program in the mid-1800s but also foresaw the digital future more than a hundred years to come.

This is part of Feminist Frequency’s Ordinary Women series, which also covered women like Ida B. Wells and Emma Goldman.

We Work Remotely

Calculating Ada

posted by Jason Kottke   Oct 11, 2016

From the BBC, an hour-long documentary on Ada Lovelace, the world’s first computer programmer.

You might have assumed that the computer age began with some geeks out in California, or perhaps with the codebreakers of World War II. But the pioneer who first saw the true power of the computer lived way back, during the transformative age of the Industrial Revolution.

Happy Ada Lovelace Day, everyone!

RIP Seymour Papert

posted by Jason Kottke   Aug 03, 2016

Seymour Papert, a giant in the worlds of computing and education, died on Sunday aged 88.

Dr. Papert, who was born in South Africa, was one of the leading educational theorists of the last half-century and a co-director of the renowned Artificial Intelligence Laboratory at the Massachusetts Institute of Technology. In some circles he was considered the world’s foremost expert on how technology can provide new ways for children to learn.

In the pencil-and-paper world of the 1960s classroom, Dr. Papert envisioned a computing device on every desk and an internetlike environment in which vast amounts of printed material would be available to children. He put his ideas into practice, creating in the late ’60s a computer programming language, called Logo, to teach children how to use computers.

I missed out on using Logo as a kid, but I know many people for whom Logo was their introduction to computers and programming. The MIT Media Lab has a short remembrance of Papert as well.

P vs. NP and the Computational Complexity Zoo

posted by Jason Kottke   May 20, 2016

When Grade-A nerds get together and talk about programming and math, a popular topic is P vs NP complexity. There’s a lot to P vs NP, but boiled down to its essence, according to the video:

Does being able to quickly recognize correct answers [to problems] mean there’s also a quick way to find [correct answers]?

Most people suspect that the answer to that question is “no”, but it remains famously unproven.

In fact, one of the outstanding problems in computer science is determining whether questions exist whose answer can be quickly checked, but which require an impossibly long time to solve by any direct procedure. Problems like the one listed above certainly seem to be of this kind, but so far no one has managed to prove that any of them really are so hard as they appear, i.e., that there really is no feasible way to generate an answer with the help of a computer.

A regular expression for finding prime numbers

posted by Jason Kottke   Feb 12, 2015

Given that there’s so much mathematicians don’t know about prime numbers, you might be surprised to learn that there’s a very simple regular expression for detecting prime numbers:


If you’ve got access to Perl on the command line, try it out with some of these (just replace [number] with any integer):

perl -wle 'print "Prime" if (1 x shift) !~ /^1?$|^(11+?)\\1+$/' [number]

An explanation is here which I admit I did not quite follow. A commenter at Hacker News adds a bit more context:

However while cute, it is very slow. It tries every possible factorization as a pattern match. When it succeeds, on a string of length n that means that n times it tries to match a string of length n against a specific pattern. This is O(n^2). Try it on primes like 35509, 195341, 526049 and 1030793 and you can observe the slowdown.

Lauren Ipsum

posted by Jason Kottke   Nov 21, 2014

Lauren Ipsum is a book about computer science for kids (age 10 and up) published by No Starch Press.

Meet Lauren, an adventurer who knows all about solving problems. But she’s lost in the fantastical world of Userland, where mail is delivered by daemons and packs of wild jargon roam.

Lauren sets out for home, traveling through a journey of puzzles, from the Push and Pop Cafe to the Garden of the Forking Paths. As she discovers the secrets of Userland, Lauren learns about computer science without even realizing it-and so do you!

Sounds intriguing. And 1000 bonus points for making the protagonist a girl. There’s an older self-published version of the book that’s been out for a couple of years. I like the older description slightly better:

Laurie is lost in Userland. She knows where she is, or where she’s going, but maybe not at the same time. The only way out is through Jargon-infested swamps, gates guarded by perfect logic, and the perils of breakfast time at the Philosopher’s Diner. With just her wits and the help of a lizard who thinks he’s a dinosaur, Laurie has to find her own way home.

Lauren Ipsum is a children’s story about computer science. In 20 chapters she encounters dozens of ideas from timing attacks to algorithm design, the subtle power of names, and how to get a fair flip out of even the most unfair coin.

Has anyone read it?

Tweet programming

posted by Jason Kottke   Sep 19, 2014

You can now program by tweeting snippets of Wolfram Language code to their Tweet-a-Program bot, @WolframTaP. To test it out, I tweeted:

And got back:


Getting high on programming

posted by Jason Kottke   Jun 20, 2014

David Auerbach writes about the high you get from coding.

These days I write more than I code, but one of the things I miss about programming is the coder’s high: those times when, for hours on end, I would lock my vision straight at the computer screen, trance out, and become a human-machine hybrid zipping through the virtual architecture that my co-workers and I were building. Hunger, thirst, sleepiness, and even pain all faded away while I was staring at the screen, thinking and typing, until I’d reach the point of exhaustion and it would come crashing down on me.

It was good for me, too. Coding had a smoothing, calming effect on my psyche, what I imagine meditation does to you if you master it.

Auerbach asserts that there’s something different about the flow state one enters while programming, compared to those brought on by making art, writing, etc. Over the years, I’ve written, designed, and programmed for a living, and programming is, by far, the thing that gets me the best high. I’ve definitely had productive multi-hour Photoshop and writing benders, but coding blocks out the world and the rest of myself like nothing else. In attempting to articulate to friends why I enjoy programming more than design or writing, I’ve been explaining it like this: for me, the coding process is all or nothing and has a definitive end.

When code doesn’t work within the specifications, it’s 100% broken. It won’t compile, the web server throws an error, or gives the wrong output. Writing and design almost always sorta work…even a first draft or an initial design communicates something to the reader/viewer. When the code works within the specifications, it’s done. The writing or design process is never done; even a great piece of writing or the best design can be improved incrementally or even scrapped altogether to go in a different and potentially more fruitful direction. Maybe, for me, programming’s definite ending is what makes it so enjoyable. The flow state comes from knowing that, while the journey is difficult and maddening and messily creative (just as with writing or design), there’s a definite point at which it’s done and you can move on to the next challenge. (via 5 intriguing things)

The infinitely large .zip file

posted by Jason Kottke   Jun 16, 2014

It’s possible to make a .zip file that contains itself infinitely many times. So a 440 byte file could conceivably be expanded into eleventy dickety two zootayunafliptobytes of data and beyond. Here’s the full explanation.

Folk dancing sorts

posted by Jason Kottke   Apr 24, 2014

Programming sorting techniques visualized through Eastern European folk dancing. For instance, here’s the bubble sort with Hungarian dancing:

See also sorting algorithms visualized. (via @viljavarasto)

Wolfram Language demo

posted by Jason Kottke   Feb 27, 2014

Stephen Wolfram (of Mathematica and A New Kind of Science fame) says the upcoming Wolfram Language is his company’s “most important technology project yet”.

We call it the Wolfram Language because it is a language. But it’s a new and different kind of language. It’s a general-purpose knowledge-based language. That covers all forms of computing, in a new way.

There are plenty of existing general-purpose computer languages. But their vision is very different — and in a sense much more modest — than the Wolfram Language. They concentrate on managing the structure of programs, keeping the language itself small in scope, and relying on a web of external libraries for additional functionality. In the Wolfram Language my concept from the very beginning has been to create a single tightly integrated system in which as much as possible is included right in the language itself.

The demo video is a little mind-melting in parts:

Not sure if this will take off or not, but the idea behind it all is worth exploring.

Sorting algorithms visualized

posted by Jason Kottke   Nov 13, 2013

This video visualization of 15 different sorting algorithms is mesmerizing. (Don’t forget the sound.)

An explanation of the process. You can play with several different kinds of sorts here.

Legend of the Black Perl

posted by Jason Kottke   Sep 23, 2013

Black Perl is a poem written in valid Perl 3 code:

BEFOREHAND: close door, each window & exit; wait until time.
open spellbook, study, read (scan, select, tell us);
write it, print the hex while each watches,
reverse its length, write again;
kill spiders, pop them, chop, split, kill them.
unlink arms, shift, wait & listen (listening, wait),
sort the flock (then, warn the "goats" & kill the "sheep");
kill them, dump qualms, shift moralities,
values aside, each one;
die sheep! die to reverse the system
you accept (reject, respect);
next step,
kill the next sacrifice, each sacrifice,
wait, redo ritual until "all the spirits are pleased";
do it ("as they say").
do it(*everyone***must***participate***in***forbidden**s*e*x*).
return last victim; package body;
exit crypt (time, times & "half a time") & close it,
select (quickly) & warn your next victim;
AFTERWORDS: tell nobody.
wait, wait until time;
wait until next year, next decade;
sleep, sleep, die yourself,
die at last
# Larry Wall

It’s not Shakespeare, but it’s not bad for executable code.

Regex crossword puzzles

posted by Jason Kottke   Jul 16, 2013

This is a surprisingly helpful activity for learning about regular expressions. (via @bdeskin)

How to efficiently sort socks

posted by Jason Kottke   Jan 22, 2013

From Stack Overflow, a question about how to efficient sort a pile of socks.

Yesterday I was pairing the socks from the clean laundry, and figured out the way I was doing it is not very efficient. I was doing a naive search — picking one sock and “iterating” the pile in order to find its pair. This requires iterating over n/2 * n/4 = n^2/8 socks on average.

As a computer scientist I was thinking what I could do? sorting (according to size/color/…) of course came into mind to achieve O(NlogN) solution.

And everyone gets it wrong. The correct answer is actually:

1) Throw all your socks out.

2) Go to Uniqlo and buy 15 identical pairs of black socks.

3) When you want to wear socks, pick any two out of the drawer.

4) When you notice your socks are wearing out, goto step 1.


Source code for Apollo and Gemini programs

posted by Jason Kottke   Apr 25, 2012

An extensive collection gathered from all over the internet of the source code and documentation for NASA’s Apollo and Gemini programs. Here’s part of the source code for Apollo 11’s guidance computer.

And here’s an interesting tidbit about the core rope memory used for the Apollo’s guidance computer:

Fun fact: the actual programs in the spacecraft were stored in core rope memory, an ancient memory technology made by (literally) weaving a fabric/rope, where the bits were physical rings of ferrite material.

“Core” memory is resistant to cosmic rays. The state of a core bit will not change when bombarded by radiation in Outer Space. Can’t say the same of solid state memory.

Woven memory! Also called LOL memory:

Software written by MIT programmers was woven into core rope memory by female workers in factories. Some programmers nicknamed the finished product LOL memory, for Little Old Lady memory.

A search for programming knowledge and _why

posted by Jason Kottke   Mar 15, 2012

For her yearly month-long project at Slate, Annie Lowrey wanted to learn how to code. She picked Ruby and became interested in the story of _why, the mysterious Ruby hacker who disappeared suddenly in 2009. In a long article at Slate, Lowrey shares her experience learning to program and, oh, by the way, tracks down _why. Sort of.

The pickaxe book first shows you how to install Ruby on your computer. (That leads to a strange ontological question: Is a programming language a program? Basically, yes. You can download it from the Internet so that your computer will know how to speak it.)

Then the pickaxe book moves on to stuff like this: “Ruby is a genuine object-oriented language. Everything you manipulate is an object, and the results of those manipulations are themselves objects. However, many languages make the same claim, and their users often have a different interpretation of what object-oriented means and a different terminology for the concepts they employ.”

Programming manual, or Derrida? As I pressed on, it got little better. Nearly every page required aggressive Googling, followed by dull confusion. The vocabulary alone proved huge and complex. Strings! Arrays! Objects! Variables! Interactive shells! I kind of got it, I would promise myself. But the next morning, I had retained nothing. Ruby remained little more than Greek to me.

Beginner’s guide to developing iOS apps

posted by Jason Kottke   Feb 29, 2012

Very much trying not to read the entirety of this beginner’s guide to developing iOS apps published by Apple because then I’ll be tempted to actually make one.

Code iPad games on your iPad

posted by Jason Kottke   Oct 27, 2011

Codify is an iPad app that allows you to code iPad games on your iPad.

We think Codify is the most beautiful code editor you’ll use, and it’s easy. Codify is designed to let you touch your code. Want to change a number? Just tap and drag it. How about a color, or an image? Tapping will bring up visual editors that let you choose exactly what you want.

Codify is built on the Lua programming language. A simple, elegant language that doesn’t rely too much on symbols — a perfect match for iPad.

(via df)

Commit Logs From Last Night

posted by Jason Kottke   Oct 18, 2011

Sort of a nerdy version of Texts From Last Night, Commit Logs From Last Night chronicles the often frustrating process of committing working code.

SUPER ugly, but it works

Added a bunch of semi colons that were missing for some balls weird reason.

Oops, left some debugging crap

RIP Dennis Ritchie

posted by Jason Kottke   Oct 13, 2011

Dennis Richie passed away last week. Richie created the C programming language, was a key contributer to UNIX, and wrote an early definitive work on programming, The C Programming Language.

We lost a tech giant today. Dennis MacAlistair Ritchie, co-creator of Unix and the C programming language with Ken Thompson, has passed away at the age of 70. Ritchie has made a tremendous amount of contribution to the computer industry, directly and indirectly affecting (improving) the lives of most people in the world, whether you know it or not.

These sorts of comparisons are inexact at best, but Richie’s contribution to the technology industry rivals that of Steve Jobs’…Richie’s was just less noticed by non-programmers.

Scripting language comparisons

posted by Jason Kottke   Aug 17, 2011

An extensive side-by-side reference sheet of four scripting languages (PHP, Python, Perl, and Ruby) with which you can compare how the different languages handle variable declarations, concatenations, objects, and hundreds of other things. Great cheatsheet for learning a new language when you’re already familar with one of the others.

Weird software bugs

posted by Jason Kottke   Apr 28, 2011

From Wikipedia, a list of unusual software bugs, including the Mandelbug and Heisenbug. My favorite is the Schrödinbug:

A schrödinbug is a bug that manifests only after someone reading source code or using the program in an unusual way notices that it never should have worked in the first place, at which point the program promptly stops working for everybody until fixed.

(via @greglopp)

Regular expression tester

posted by Jason Kottke   Apr 18, 2011

Related to the regex generator I posted last week, here’s a regular expression tester…you plug in your regex and it’ll match test strings as you type. (thx, chris)

Magical regular expression generator

posted by Jason Kottke   Apr 13, 2011

On text2re.com, you can input some text you want to use a regular expression on, click on what you want to match, and it’ll generate the regular expression for you.

This system acts as a regular expression generator. Instead of trying to build the regular expression, you start off with the string that you want to search. You paste this into the site, click submit and the site finds recognisable patterns in your string. You then select the patterns that you are interested in and it writes a fully fledged program that extracts those patterns from that string. You then copy the program into your editor or IDE and play with it to integrate it into your program.

This just totally broke my brain.

On weekend web apps

posted by Jason Kottke   Dec 20, 2010

Andre Torrez offers some advice for those who think that they can clone a popular web app over the weekend. The best part — or the worst, if you’re the aspiring weekend programmer — is that each item on the list is a little Pandora’s box of Alice’s rabbit holes. Like this:

Lost password flow. You’ll want to generate a key and store it someplace for when someone requests to reset their password. So that’s another email that has to go out.

If you actually want your email to arrive at its destination, you’re gonna have to worry about all this. Or go through a third-party service, which is another interface (and bill (and moving part)) that you need to worry about. You get the point…making a web app work for more than just one person is hard, way harder than it looks unless you’ve done it.

Lady Gaga sings about Java programming

posted by Jason Kottke   Aug 20, 2010

Ok, so it’s not Gaga (and certainly not Christopher Walken), but she does work “object oriented” into the lyrics.

This is possibly the best production of the worst idea I’ve ever seen.

Ada Lovelace, the first computer programmer

posted by Jason Kottke   Jun 18, 2010

Charles Babbage built one of the first mechanical calculating machines but Ada Lovelace was the first to show how the machine’s arithmetic function could be abstracted to produce things other than numbers: language, graphics, or music.

There are several other Information Pioneers shorts available on Vimeo, including profiles of Tim Berners-Lee, Alan Turing, and Hedy Lamarr.

When programming errors attack!

posted by Jason Kottke   Mar 23, 2010

From a bunch of security experts, the top 25 most dangerous programming errors that can lead to serious software vulnerabilities.

Cross-site scripting and SQL injection are the 1-2 punch of security weaknesses in 2010. Even when a software package doesn’t primarily run on the web, there’s a good chance that it has a web-based management interface or HTML-based output formats that allow cross-site scripting. For data-rich software applications, SQL injection is the means to steal the keys to the kingdom. The classic buffer overflow comes in third, while more complex buffer overflow variants are sprinkled in the rest of the Top 25.

Programming lessons

posted by Jason Kottke   Jan 13, 2010

A programmer lists 20 lessons learned in the past 20 years.

5. You are not the best at programming. Live with it. — I always thought that I knew so much about programming, but there is always someone out there better than you. Always. Learn from them.

(via @h_fj)