Wadler's Blog

Reading beside the lines: Using indentation to rank revisions by complexity

2012-01-11T16:34:00.000Z

I'm always on the lookout for good papers that offer an empirical approach to programming languages. Thanks to Oscar Nierstrasz for suggesting this one, which shows that indentation is as effective as more sophisticated measures at classifying program complexity.

Abram Hindle, Michael W. Godfrey,
Richard C. Holt, Reading beside the lines: Using indentation to rank revisions by complexity, Science of Computer Programming, Volume 74, Issue 7, 1 May 2009, Pages 414–429.

Maintainers often face the daunting task of wading through a collection of both new and old revisions, trying to ferret out those that warrant detailed inspection. Perhaps the most obvious way to rank revisions is by lines of code (LOC); this technique has the advantage of being both simple and fast. However, most revisions are quite small, and so we would like a way of distinguishing between simple and complex changes of equal size. Classical complexity metrics, such as Halstead’s and McCabe’s, could be used but they are hard to apply to code fragments of different programming languages. We propose a language-independent approach to ranking revisions based on the indentation of their code fragments. We use the statistical moments of indentation as a lightweight and revision/diff friendly metric to proxy classical complexity metrics. We found that ranking revisions by the variance and summation of indentation was very similar to ranking revisions by traditional complexity measures since these measures correlate with both Halstead and McCabe complexity; this was evaluated against the CVS histories of 278 active and popular SourceForge projects. Thus, we conclude that measuring indentation alone can serve as a cheap and accurate proxy for computing the code complexity of revisions.

Computing at School

2012-01-11T10:19:00.000Z

Hurrah! The government appears to finally understand that there is a difference between teaching IT and teaching computing, and that we need to move from the former to the latter in schools. Join the campaign at Computing at School. The Guardian is running a digital literacy campaign. Computing is the new Latin!

Scotland Loves Anime

2011-12-20T14:32:00.000Z

A belated shout out to Andrew Partridge, organiser of Scotland Loves Anime, which played at the Edinburgh Filmhouse 14&endash;16 October. With my family I saw Coicent, Towanoquon, Five Numbers, and Oblivion Island: Haruka and the Magic Mirror. I particularly liked Coicent, illustrated above, because it is set in Nara and I recoginised the deer and the temple that feature in it from my visit there as an invited speaker at RTS, back in April 2005. But the real surprise was when Andrew, introducing Oblivion Island, recognised me sitting in the audience, and reminisced about learning Haskell and monads in first year at university, where he was a student in my first-year class. He's done a great job with Scotland Loves Anime, and it's wonderful to see the wide variety of activities our students initiate.

List.It, FeedMe, NB, Exhibit

2011-12-20T14:12:00.000Z

Last October, we had a visit from David Karger, speaking on "Building User Interfaces that Entice People to Manage Better Information"; only now, alas, am I getting around to posting it on my blog. He spoke on four systems: List.It, a note keeping tool that runs in browsers; FeedMe, a tool for sharing interesting things you find on the web, NB, a collaborative tool for teaching environments, and Exhibit, a Javascript library for posting Excel spreadsheets as web pages. (The screenshot above is from Exhibit.) What I particularly liked about his approach was the interplay between design and experiments to determine how users interact with the systems.

Usability of Programming Languages

2011-12-20T13:56:00.000Z

I've mentioned a few times my desire that programming languages have a firmer foundation in science, notably psychology. Of course, there is a large body of work in this area that most programming language researchers (in particular, me) know nothing about. Here is a pointer to a course on the subject, taught at Cambridge by Alan Blackwell (above). Blackwell worked with Thomas Green. Green is the author of one of the few papers on the subject I know that has a clear, usable result: people find it easier to work with a flat sequence of conditions than with a nest of 'if' statements. Thanks to Lambda the Ultimate for a pointer to Blackwell's course.

Marshmallows and Pensions

2011-11-29T10:58:00.001Z

[An open letter sent to the School of Informatics of the University of Edinburgh.]

We write to urge you to join the strike on 30 November, sponsored by UCU and EIS and timed to coincide with actions by unions across the UK. If you are not a member of UCU or EIS, we urge you to support the strike by not coming in to work and by refusing to cross picket lines.

In 1972, psychologist Walter Mischel conducted an experiment at Stanford University. Over 600 children, aged 4 to 6, were put into a room free of distractions, given a marshmallow, and told they would be left alone for fifteen minutes. They were free to eat the marshmallow, but if they held out for fifteen minutes, they would be given a second marshmallow as a reward. One third held out for the bigger payoff. A follow-up study, 18 years later, revealed that the one-third who deferred gratification were remarkably more successful across a range of activities, including scoring more than 200 points higher on SAT college admission tests. Holding out for the second marshmallow is a salient indicator of success in later life.

If ability to delay gratification correlates with success, one might expect successful people to take a long-term view. For instance, one might expect academics in a leading institution to rate receiving a decent pension more highly than the hassle of supporting a strike. But ask someone in the Informatics Forum if they are planning to strike, and they are likely to say "No, I have a meeting booked for that day." To whom do they owe more? The person they are meeting? Their future self? Or how about future hires, who will be hit hardest by the cuts, and future students, who deserve to inherit a university system that remains world-class?

Over the last year, USS has imposed a drastic cut in pensions: 36% of the value of the pension for Mary, a new lecturer promoted to senior lecturer after ten years; and 12% of the value of the pension for John, someone just like Mary except he's currently employed rather than a new hire. This is a classic divide-and-rule tactic. While staff may be less inclined to fight a 12% cut than a 36% cut, the two-tier system is unfair and unlikely to last: historically, two-tier systems are updated within a few years by moving everyone to the lower tier. Details of the cuts are listed below.

What about our students? EUSA, the student union, is supporting the strike. They know that these cuts will weaken universities. During the last strike, in March, sometimes there were more students than staff manning the pickets. If our students support the strike, shouldn't we support them?

Aren't pensions gold-plated? The UK historically spends less on pensions than other European nations. Private-sector pensions have degraded over the past few decades; we should support efforts to restore those to decent levels, not agree to decimating public-sector pensions as well. It's not fair for public employees to give up their pensions to pay for bank bailouts.

In this day and age, can we afford it? The UK is renowned for its world-class universities: Cambridge, Oxford, Imperial, Edinburgh, Manchester. Look at a list of the top-ten universities in the world, and you will see only universities from the US and UK. That excellence is a huge driver of innovation and growth. If the UK stops its investment in universities, it won't be long before we feel that loss throughout the economy. So the question should be, can we afford to shortchange universities, particularly the younger generation that is hardest hit by these proposals?

It may be easier to give in, but the right plan is to keep our pensions and our universities strong for future generations. Let's hold out for the second marshmallow.

Yours,

Philip Wadler
Nigel Goddard
Alan Bundy

A summary of the changes.

Introduction of a two-tier system. Current staff who pay into the pension fund for forty years receive a pension of one-half their final salary; new hires who do the same receive a pension of one-half their average salary. Basing pensions on average rather than final salary may be sensible, but to do so with no adjustment in multiplier suggests employers are using this as an excuse to slip in a large cut; it means new hires receive about 2/3 the benefits received by old hires. Further, if this follows the course of other two-tier schemes, the upper tier will be eliminated in favour of the lower, and old hires as well as new will see their pension slashed.

Capping cover for inflation. Previous arrangements offered full cover for inflation; new arrangements offer full cover to 5% and half cover to 15%---that is, a 10% increase when inflation is 15% or higher. Inflation averaged 16% per year between 1974 and 1980; a cut of 6% per year over six years compounds to a 31% reduction, lasting over the remaining lifetime of the pension.

Altering the index of inflation. The Retail Price Index (RPI) is replaced by the Consumer Price Index (CPI). RPI is calculated with an arithmetic mean, CPI with a geometric mean, which is always less. CPI runs about 0.7% lower than RPI; a cut of 0.7% per year over twenty years compounds to a 13% reduction.

Changes to conditions. Staff that take a career break of 30 months will be demoted from the final-salary to average-salary scheme, about a 1/3 cut; this particularly affects women. The same will happen to staff that are made redundant, a double whammy: if you lose your job, you also lose a large proportion of your pension.

Robin Hood

2011-11-15T22:00:00.000Z

I'm a fan of Bill Nighy, doubly so after viewing this video on the Robin Hood Tax, also known as the Financial Transaction Tax or FTT. Watch the video now, if you haven't already: it's informative, amusing, and short. And brilliantly acted.

The standard argument against the tax is that any country implementing it unilaterally would drive business away. But the UK already imposes a Stamp Tax of 0.5% (as compared to the 0.05% of the FTT) on share trades, and this doesn't appear to have done the London Stock Exchange irreparable harm. Further, the tax can be arranged to apply to any transaction carried out by a UK business, regardless of where the transaction itself occurs; few companies would abandon the country just to save 0.05% on currency and derivative trades. Some other counterarguments appear here.

Happy 13th, Expression Problem

2011-11-15T20:35:00.000Z

Thanks to Francois Garillot and an intriguing thread on Lambda the Ultimate for reminding me that the Expression Problem reached it's 13th birthday last week. No bar mitzvah is planned.

Alfred Ernest Marples, Baron Marples of Wallasey, is very sad because the Public Data Corporation wants to lock public data away behind fees.

2011-10-25T22:35:00.001+01:00

This site describes the issues, and makes is easy you submit your opinion to the public consultation via a form.

Please respond now! Time runs out on 27th October 2011. It's just like the Mayan apocalypse, but for open data.

Goldman Sachs

2011-10-09T22:09:00.000+01:00

I've heard it said that protestors at Occupy Wall Street aren't sure what they're protesting against. If they read this article by Matt Taibbi in Rolling Stone, they'd know.

Israel and Palestine

2011-10-05T13:52:00.000+01:00

In the wake of Abbas's speech at the UN, I was delighted to receive a statement in support of Palestinian independence signed by prominent Israelis.

The Land of Israel is the birthplace of the Jewish people where its identity was formed.
The Land of Palestine is the birthplace of the Palestinian people where its identity was shaped.We, the citizens of Israel, call on the public to support the recognition of a democratic Palestinian state as a condition for ending the conflict, and reaching agreed borders on the basis of the 1967 borders. Recognition of such a Palestinian state is vital for Israel's existence. It is the only way to guarantee the resolution of the conflict by negotiations, to prevent the eruption of another round of massive violence and end the risky isolation of Israel in the world.

My thanks to David Harel, one of the signatories, for passing this on. Harel is a prominent computer scientist, winner of many awards including the ACM Karlstrom Outstanding Educator Award, the ACM SIGSOFT Outstanding Research Award, the ACM Software System Award, the Emet Prize, and the Israel Prize.

The Seven Mysterious Book Sculptures of Edinburgh

2011-09-13T12:00:00.000+01:00

An unknown individual has been leaving sculptures made from carved books at libraries and cultural spots throughout Edinburgh, addressed to their twitter feeds: @byleaveswelive (Scottish Poetry Library), @natlibscot (National Library of Scotland), @filmhouse (Filmhouse), @scotstorycenter (Scottish Storytelling Centre), @edbookfest (Edinburgh Book Festival), @edincityoflit (UNESCO Edinburgh City of Literature), @Edinburgh_CC (Edinburgh Central Library). Reported by crisdonia. Spotted via Boing Boing.

For @scotstorycenter - A gift in support of libraries, books, works, ideas..... Once upon a time there was a book and in the book was a nest and in the nest was an egg and in the egg was a dragon and in the dragon was a story.....

For 9/11

2011-09-13T11:34:00.000+01:00

By Kyle Dettman. Spotted on Boing Boing.

An experiment about static and dynamic type systems

2011-09-07T14:58:00.000+01:00

Stefan Hanenberg, An experiment about static and dynamic type systems: doubts about the positive impact of static type systems on development time, OOPSLA, Reno/Tahoe Nevada, pp. 22–35, October 2010.

If programming language design is to become a science, we need more experiments like this one.

The author measured time for 49 subjects to build a simple parser in Purity, a language similar to Smalltalk implemented for this experiment in two variants. Twenty-five subjects implemented the parser in the dynamically-typed variant, and 24 used the statically-typed variant. Two measurements were taken: the time at which the lexical scanner passed all its tests, and the percentage of tests passed by the parser after 27 hours; the tests were equally divided between accept and reject, so a random program would pass 50% of the tests.

Subjects using the dynamically-typed language completed the scanner in an average of 5.2 hours, statically-typed in an average of 7.7 hours; the difference is statistically significant at level p=0.04.
Fourteen subjects using the dynamically-typed language failed to complete the parser (that is, passed only 50% of tests), 11 subjects using the statically-typed language failed.
Subjects using the dynamically-typed language passed an average of 60.2% of the tests, subjects using the statically-typed language passed an average of 64.5% of the tests; but the difference is not statistically significant at level p=0.40.

There are many potential objections to these results. Subjects were not told to complete the scanner before working on the parser. It is not clear why Mann-Whitney's U-Test is used to assess significance rather than Student's T-Test. (I didn't check whether the T-Test yielded different significance.)

Any test of this kind is fraught with difficulties. One issue is that experimenter, to reduce variables such as familiarity or different IDEs, developed his own language, Purity, in two variants. One way around that problem would be to use Java to compare dynamically and statically typed programming: that is, compare subjects using Java 4 with Java 5, that is, Java with and without generics. In Java before generics, a collection would have type List, while in Java with generics a collection would have type List<Integer> or List<List<String>>. This would let one compare the effects of presence or absence of type information without the need to create an artificial language. It would fail to measure the benefits claimed for completely dynamic languages such as Javascript or Python, but perhaps it is ok to walk before we run. Anyone interested in collaborating on an empirical comparison of two versions of Java?

Dance Your PhD

2011-09-07T13:53:00.000+01:00

(Selection of a DNA aptamer for homocysteine using SELEX from Maureen McKeague on Vimeo.)

Let's dance!

The dreaded question. “So, what’s your Ph.D. research about?” You take a deep breath and launch into the explanation. People’s eyes begin to glaze over…

At times like these, don’t you wish you could just turn to the nearest computer and show people an online video of your Ph.D. thesis interpreted in dance form?

Now you can. And while you’re at it, you can win $1000, achieve immortal geek fame on the Internet, and be recognized by Science for your effort.

And this year, we have a new sponsor: TEDxBrussels. The creator of the best Ph.D. dance gets a free trip and hotel stay in Brussels to be crowned the winner at the TEDx conference on 22 November 2011.

The winning entry from 2010 is above. This year there are prizes for the best entries in physics, chemistry, biology, and social science. Where's informatics? (Or computer science, if you want to use the old name.) I'm dying to dance, but no contest to enter ...

Erik Schmidt on computing education in the UK

2011-09-07T13:40:00.000+01:00

In August, Edinburgh is Festival City, hosting the International Festival, the Fringe, the book festival, and many others. At the media festival, my old coauthor, Erik Schmidt (now chair of Google), delivered a keynote which included wise words on computing and education:

First: you need to bring art and science back together. Think back to the glory days of the Victorian era. It was a time when the same people wrote poetry and built bridges. Lewis Carroll didn’t just write one of the classic fairytales of all time, he was also a mathematics tutor at Oxford. James Clerk Maxwell was described by Einstein as among the best physicists since Newton - but was also a published poet.

Over the past century the UK has stopped nurturing its polymaths. There’s been a drift to the humanities - engineering and science aren’t championed. Even worse, both sides seem to denigrate the other - to use what I’m told is the local vernacular, you’re either a ‘luvvy’ or a ‘boffin’.

To change that you need to start at the beginning with education. We need to reignite children’s passion for science, engineering and maths. In the 1980’s the BBC not only broadcast programming for kids about coding, but (in partnership with Acorn) shipped over a million BBC Micro computers into schools and homes. That was a fabulous initiative, but it’s long gone. I was flabbergasted to learn that today computer science isn’t even taught as standard in UK schools. Your IT curriculum focuses on teaching how to use software, but gives no insight into how it’s made. That is just throwing away your great computing heritage.

At college-level too, the UK needs to provide more encouragement and opportunity for people to study science and engineering. In June, President Obama announced a programme to train 10,000 more engineers a year. I hope others will follow suit - the world needs more engineers. I saw the other day that on The Apprentice Alan Sugar said engineers are no good at business. Really? I don’t think we’ve done too badly!

If the UK’s creative businesses want to thrive in the digital future, you need people who understand all facets of it integrated from the very beginning. Take a lead from the Victorians and ignore Lord Sugar: bring engineers into your company at all levels, including the top.

A better tube

2011-08-19T14:21:00.000+01:00

Two alternatives to the traditional London Tube map, one closer to geographically acurate and one with distortion grid in the background. Spotted on Boing Boing.

The City and The City

2011-08-02T12:00:00.000+01:00

Looking forward to China Mieville's appearance at the Edinburgh Festival, my wife discovered that Edinburgh libraries have two listings for The City and The City: one with the title as expected, filed under Science Fiction, and one with the second half of the title backward (trying to emulate the mirror writing on the cover), filed under Crime.

Workers facing a bleak old age says pension review

2011-08-02T11:24:00.000+01:00

Yesterday's news contained “a wake-up call” on the poor state of private pensions. My union is in dispute over changes to our pension plan (which affect new hires more severely than old folk like me). The government argues that public sector pensions need to change because they are out of line with provision in the private sector. But, as this report shows, the problem is not that public sector pensions are “gold plated” but that private sector pensions are woefully inadequate.

4-Profit University

2011-07-01T15:52:00.004+01:00

The coalition has announced plans to encourage private firms to set up `for profit' degree courses. The idea comes from the US, and to see the high esteem in which such institutions are held there, have a look at the above strip from Tom The Dancing Bug. The Guardian warns the threat to universities is real and imminent. Early day motion 1999 raises concern about for-profit universities; They Work For You make it easy to write to your MP to urge him or her to support it.

The Economist notices

2011-06-13T20:35:00.003+01:00

The concurrency crisis is upon us: Moore's Law will continue only if we learn to write parallel programs. This is important enough you might expect it to show up in the mainstream press, and at last it is. From the 2 June 2011 issue of the Economist:

Meanwhile, a group of obscure programming languages used in academia seems to be making slow but steady progress, crunching large amounts of data in industrial applications and behind the scenes at large websites. Two examples are Erlang and Haskell, both of which are “functional programming” languages.

Such languages are based on a highly mathematical programming style (based on the evaluation of functions) that is very different from traditional, “imperative” languages (based on a series of commands). This puts many programmers off. But functional languages turn out to be very well suited to parallel programming. Erlang was originally developed by Ericsson for use in telecoms equipment, and the language has since been adopted elsewhere: it powers Facebook’s chat feature, for example. Another novel language is Scala, which aims to combine the best of both functional and traditional languages. It is used to run the Twitter, LinkedIn and Foursquare websites, among others.

A combinator library for the design of railway track layouts

2011-06-10T15:33:00.002+01:00

How cool is this? Barney Stratford, Journal of Functional Programming, 21(3), May 2011.

In the design of railway track layouts, there are only a small number of geometric configurations that are used in practice, and a number of constraints as to how those configurations can be fitted together to create a whole layout. In order to solve these problems, we construct a Haskell combinator library. The library has been used for the design of real-world track layouts.

RSAnimate

2011-06-10T15:09:00.003+01:00

The RSA has a series of videos cleverly animated from lectures. I would love to illustrate a lecture this way! Spotted by Maurice Naftalin.

Case analysis

2011-04-27T21:12:00.003+01:00

A Latin saying, heard on Escape Pod:

It is well to remember that there are five reasons for drinking: The arrival of a friend; one's present or future thirst; the excellence of the wine; or any other reason.

The Grim Threat to British Universities

2011-04-27T18:21:00.002+01:00

From the New York Review of Books:

The British universities, Oxford and Cambridge included, are under siege from a system of state control that is undermining the one thing upon which their worldwide reputation depends: the caliber of their scholarship. The theories and practices that are driving this assault are mostly American in origin, conceived in American business schools and management consulting firms. They are frequently embedded in intensive management systems that make use of information technology (IT) marketed by corporations such as IBM, Oracle, and SAP. They are then sold to clients such as the UK government and its bureaucracies, including the universities. This alliance between the public and private sector has become a threat to academic freedom in the UK, and a warning to the American academy about how its own freedoms can be threatened.

VS Naipaul’s Seven Rules for Beginners

2011-04-25T12:23:00.002+01:00

Following yesterday's post on Alfred Kahn, here is advice from VS Naipaul, winner of the Nobel Prize for Literature in 2001.

VS Naipaul’s Rules for Beginners
1. Do not write long sentences. A sentence should not have more than ten or twelve words.
2. Each sentence should make a clear statement. It should add to the statement that went before. A good paragraph is a series of clear, linked statements.
3. Do not use big words. If your computer tells you that your average word is more than five letters long, there is something wrong. The use of small words compels you to think about what you are writing. Even difficult ideas can be broken down into small words.
4. Never use words whose meaning you are not sure of. If you break this rule you should look for other work.
5. The beginner should avoid using adjectives, except those of colour, size and number. Use as few adverbs as possible.
6. Avoid the abstract. Always go for the concrete.
7. Every day, for six months at least, practice writing in this way. Small words; short, clear, concrete sentences. It may be awkward, but it’s training you in the use of language. It may even be getting rid of the bad language habits you picked up at the university. You may go beyond these rules after you have thoroughly understood and mastered them.

Alfred Kahn's memo

2011-04-24T14:32:00.002+01:00

Alfred Kahn wrote a celebrated memo on writing with clarity. As described in The New York Times:

Though written long before the Internet age, the memo immediately went viral. It was published verbatim in The Washington Post, which also praised it in an accompanying editorial. It generated a marriage proposal from a Boston Globe columnist, who gushed: “Alfred Kahn, I love you. I know you’re in your late 50s and are married, but let’s run away together.” A Singapore newspaper suggested that Mr. Kahn be awarded a Nobel Prize. A Kansas City newspaper urged him to run for president. And, shortly after the memo’s appearance, he was appointed to the usage panel of the American Heritage Dictionary, a position he held until his death.

Here is the memo in full, spotted at here and here. Spotted via Boing Boing.

Terje Sorgjerd, The Aurora

2011-04-23T16:24:00.001+01:00

The Aurora from Terje Sorgjerd on Vimeo.

I've never seen the northern lights, I hope I will one day.

Sorting algorithms as folk dances

2011-04-12T14:57:00.002+01:00

Bubble sort, shell sort, insertion sort, and selection sort, each as a Hungarian, Romanian, or Gypsy folk dance. Alas, all the algorithms are O(n^2). I long to see an O(n log n) waltz, or better yet O(n) leaping into buckets. Spotted via Boing Boing.

An Empirical Comparison of Seven Programming Languages

2011-04-11T16:34:00.002+01:00

Lambda the Ultimate has a post describing a paper by Shane Markstrum bewailing the unjustified claims one finds in papers on programming languages. I completely agree with him, but his plan seems to be to thoroughly document the current poor state of the science; I wish that instead he would do one study of the form that he (and I) would like to see. Markstrum's bibliography lists a paper performing a study of that sort, by Lutz Prechelt of Karlsruhe, and I've listed it above. Here's to more such studies!

Another paper bewailing the lack of empiricism for computing generally is Experimental evaluation in computer science: A quantitative study by Walter F. Tichy, Paul Lukowicz, Lutz Prechelt and Ernst A. Heinz. (Yes, it's the same Prechelt.)

Surface Detail

2011-03-27T11:49:00.002+01:00

Surface detail from subBlue on Vimeo.

Video of a 3D fractal by subBlue. Anyone know which fractal this is or how it is generated? Thanks to Mike Fourman.

Why I am on strike

2011-03-23T22:49:00.003Z

An open letter to my colleagues in the School of Informatics.

Colleagues,

Here are four people to think of when considering whether to join the
UCU strike to preserve our pensions on Thursday 24 March.

Yourself. The changes to pensions are estimated to remove £150K in
value over the lifetime of your pension (presuming the two-tier scheme
stays in place, see below). The most significant changes don't take
effect immediately, but bite over time:

Capping cover for inflation. Full cover to 5%, half cover to 15%;
that is, a 10% increase when inflation is 15% or higher. Recall
inflation averaged 16% per year between 1974 and 1980: a cut of 6%
over six years compounds to a 31% reduction, lasting over the
remaining lifetime of the pension.
Altering the index of inflation from RPI to CPI. The former is
calculated with an arithmetic mean, the latter with a geometric
mean, which is always less. CPI runs about 0.7% lower than RPI;
a cut of 0.7% over twenty years compounds to a 13% reduction.
Introduction of a two-tier system, with significantly lower
payouts to new hires (see next point, re: Jill). If this follows
the course of other two-tier schemes, the upper tier will be
eliminated in favour of the lower, and old hires will see their
pension slashed.

Jill, the next lecturer we hire. Old hires who pay into the pension
fund for forty years receive a pension of one-half their final salary;
new hires who do the same receive a pension of one-half their
*average* salary. Basing pensions on average rather than final salary
may be sensible, but to do so with no adjustment in multiplier makes
it appear that employers are using this as an excuse to slip in a
large cut. The changes are estimated to remove £450K in value over
the lifetime of a new hire's pension.

Bill, a student ten years from now. In the long run, our goal is to
keep our Universities strong for students and the country. On the
picket line last Thusday, I saw more students than lecturers.

Me. I saw lecturers cross the picket line on the grounds that they
had an appointment, and did not want to inconvenience the person they
were to meet. If you are one of them, perhaps your politeness would
extend to allowing me to retire with a decent pension.

Thank you for your consideration, -- P

Law of Proverbs

2011-03-23T11:05:00.003Z

I propose the following Law of Proverbs: for every proverb, there is an equal and opposite proverb. Examples:

A stitch in time saves nine./If it ain't broke, don't fix it.

In for a penny, in for a pound./Don't throw good money after bad.

What the eye doesn't see, the heart doesn't grieve over./Truth will out.

Don't throw the baby out with the bathwater./Make a clean sweep of it.What are your favourites?

Why you should consider a post at NSF

2011-03-15T10:10:00.002Z

The NSF is interested in ensuring expertise in programming languages is represented among its program directors, and SIGPLAN is encouraging researchers to apply. This video from an NSF director explains why you should consider a post at NSF.

Theory B questions at Stack Exchange

2011-03-04T18:31:00.003Z

Stack Exchange is a website for asking and answering technical questions. One part of the web site is set aside for Theoretical Computer Science. It tends to be dominated by topics in "Theory A" (algorithms and complexity), but there is a small, intrepid group attempting to establish it as a venue for topics in "Theory B" (logic, semantics, and programming languages). To encourage further participation, they've assembled a list of some of the interesting questions they've handled. Have a look, and contribute some questions or answers of your own!

Life-critical wording

2011-03-04T12:54:00.002Z

I try to impress upon my students the importance of clear expression. Today's news contains an example where choice of the right word may be life-critical.

The experts reworded phrases that people found confusing, and then retested them in several sittings, including one-to-one interviews.

Prof Raynor said "avoid alcoholic drinks" was a good example.

"Our user tests have shown that the word "avoid" can cause confusion and that some people think it only means they should limit their alcohol intake.

"This phrase will now be replaced by the instruction: 'do not drink alcohol while taking this medicine', which is far clearer."

Other recommendations include changing "do not take indigestion remedies at the same time of day as this medicine" to "do not take indigestion remedies two hours before or after you take this medicine".

Another phrase, "do not stop taking this medicine except on your doctor's advice", becomes "warning: Do not stop taking this medicine unless your doctor tells you to stop."

Scientific programming does not compute

2011-02-16T17:55:00.004Z

An article in Nature explains why scientists need to pay more attention to basic principles of software engineering.

As a result, codes may be riddled with tiny errors that do not cause the program to break down, but may drastically change the scientific results that it spits out. One such error tripped up a structural-biology group led by Geoffrey Chang of the Scripps Research Institute in La Jolla, California. In 2006, the team realized that a computer program supplied by another lab had flipped a minus sign, which in turn reversed two columns of input data, causing protein crystal structures that the group had derived to be inverted. Chang says that the other lab provided the code with the best intentions, and "you just trust the code to do the right job". His group was forced to retract five papers published in Science, the Journal of Molecular Biology and Proceedings of the National Academy of Sciences, and now triple checks everything, he says.—Zeeya Mirali, Nature 467:775—777 (2010)

Spotted by Shriram Krishnamurthi.

Causal commutative arrows and their optimization

2011-02-02T18:00:00.002Z

Causal commutative arrows and their optimization, by Hai Liu, Eric Cheng, and Paul Hudak, ICFP 2009.

Extends arrows with two widely used concepts, loop and init. Both concepts arise quite often. Proves a normalisation theorem that reduces any program to a single use of loop, and show that in practice this can yield a speedup of two orders of magnitude. Lovely result!

As the paper notes in passing, 'loop' is closely related to the concept of 'trace' from category theory. Phil Scott is currently visiting Edinburgh, and I'm hoping he, Jeff Eggers, and I might explore the relation betwixt 'trace' and 'loop'.

An compelling example of the value of 'loop' and 'init' is the definition of integral:


integral = loop (arr (\ (v,i) -> i + dt * v) >>> init 0 >>> arr (\ i -> (i,i)))

This definition is valid for a stream of events, where each event is separated uniformly by time dt. An intriguing question is how to define integral in a similar style when the time between events is not uniform? Or for continuous behaviours rather than discrete events?

Low floors, low ceilings, and Alice

2011-02-02T17:30:00.004Z

Matthias Felleisen just introduced me to the phrase "low floor, low ceiling", which characterises precisely the worry about Kodu I expressed in my previous post: languages with a low overhead when getting started may offer low payback later.

As an example of this effect, he suggested the following critique of the innovative Alice programming environment: Through the Looking Glass: Teaching CS0 with Alice. (Thanks to Shriram Krishnamurthi for the precise reference.) I don't consider Alice in the same bowdlerized category as Kodu, so I was surprised to see that "low floor, low ceiling" might still apply.

Meanwhile, Matthias, Shriram, and others offer Teach Scheme/Reach Java as an alternative, offering a curriculum based on widely-used professional programming languages to high school and middle school children. (Addendum: Matthias and Shriram inform me that the TeachScheme website is out of date, and the preferred alternative is Program by Design.)

Pea vs. Papert; Kodu; Bootstrap

2011-02-02T12:49:00.008Z

Logo, and following on from it Scratch, Alice, and Kodu, promotes an implicit claim that in the right environment children can learn programming almost by osmosis, and that absorbing this skill improves other skills, such as planning. These implicit claims were challenged twenty-five years ago by Roy D. Pea, who discovered that school children exposed to Logo could still be confused by recursion after writing recursive programs, and that learning Logo did not improve their planning ability. Here is an overall summary, here is a paper specifically on recursion, and here is Pea's reply to an attack by Papert.

I found the second paper (Children's mental models of recursive LOGO programs) particularly interesting, as it helps to understand some of the issues my first-year students may face in learning recursion. I'm woefully ignorant of the literature on the psychology of programming, and need to learn more. Thanks to Matthias Felleisen and Emmanuel Schanzer for pointing me at this work.

What sparked my interest was a keynote on Kodu at POPL, by Matthew MacLaurin of MSR. The laudable goal of Kodu is to permit young children to program video games, as MacLaurin put it, 'to let them know the computer can do anything'. And Kodu can achieve quite spectacular results with very simple programs, but the programming model needs to be very simple to achieve this (a list of condition-action pairs). Because Kodu is so special purpose, I worry that instead of teaching children that 'computer can do anything', it will teach them that 'computers will let you build exactly what they are designed to let you build, and anything else is very difficult'. Pea's studies are orthogonal to this concern, so I'm left wondering whether Kodu will lead to a new generation of programmers or a new generation turned off by computing.

Meanwhile, Schanzer is running Bootstrap, an outgrowth of TeachScheme. "Bootstrap is a standards-based curriculum for middle-school students, which teaches them to program their own videogames using purely algebraic and geometric concepts." The start-up costs are higher than Kodu, but once started students have the full power of Scheme/Racket at their command. Seems preferable to me, but there may well be room for both in the world. More study needed! Not to mention more resources for getting proper computing (not just ICT) into schools at an early age.

Happy 2011!

2011-01-05T18:18:00.003Z

Best wishes for the New Year. (Insert traditional Scottish handshake here.) A special thank you to those who sent pointers to things of interest, some of which I reposted here, and to those who posted comments to the blog. Please keep the good stuff coming!

(Photo by Mike Levad, spotted on Boing Boing.)

The Myths of Object-Orientation

2010-12-23T13:18:00.002Z

The Myths of Object-Orientation. An after-dinner speech at ECOOP 2008, reprinted in ECOOP 2009. Spotted on Lambda the Ultimate. From the appendix:

The Sing-Song of Old Man Java
With apologies to Rudyard Kipling.

Not always was Java as now we do behold him, but a Different Language with very short types. He was small and he ran slowly, and his hype was inordinate: he danced on a TV set in the middle of California, and he went to Big God Gosling.

He went to Gosling at six before breakfast, saying, ‘Make me different from all other languages by five this afternoon.’

Up jumped Gosling from his fortress on the multicore and shouted, ‘Go away!’

He was small and he ran slowly, and his hype was inordinate: he danced on a set-top-box in the middle of California, and he went to Middle God Steele. He went to Steele at eight after breakfast, saying, ‘Make me different from all other languages; make me, also, wonderfully popular by five this afternoon.’

Up jumped Steele from his virtual reality and shouted, ‘Go away!’

He was small and he ran slowly, and his hype was inordinate: he danced on desktop in the middle of California, and he went to the Little God Gilad. He went to Gilad at ten before dinner-time, saying, ‘Make me different from all other languages; make me popular and able to run anywhere by five this afternoon.’

Up jumped Gilad from his office in Palo Alto and shouted, ‘Yes, I will!’

Instructionless learning about a complex device

2010-12-14T18:49:00.004Z

If programming language design is to become a science as well as an art, we need to study psychology. This paper describes how subjects worked out (or failed to work out) how to guide 'BigTrak', a programmable toy.

Jeff Schrager and David Klahr, Instructionless learning about a complex device, International Journal of Man-Machine Studies 25(2):153-189, August 1986.

A list is an odd creature, take 6

2010-12-14T18:35:00.004Z

Not really like a list, but a lovely animated recursion. Thanks to Michel S..

Pionen: WikiLeaks and James Bond

2010-12-09T08:23:00.003Z

The Daily Mail, of all places, notes that WikiLeaks data is stored at the Pionen data centre in Stockholm. Built inside an old nuclear bunker, it is designed to look like something out of a James Bond film.

Blame for All

2010-11-30T18:04:00.003Z

Blame for All, Amal Ahmed, Robert Bruce Findler, Jeremy G. Siek, and Philip Wadler. Symposium on Principles of Programming Languages (POPL), Austin, January 2011. (See also: STOP version).

Several programming languages are beginning to integrate static and dynamic typing, including Racket (formerly PLT Scheme), Perl 6, and C# 4.0, and the research languages Sage (Gronski, Knowles, Tomb, Freund, and Flanagan, 2006) and Thorn (Wrigstad, Eugster, Field, Nystrom, and Vitek, 2009). However, an important open question remains, which is how to add parametric polymorphism to languages that combine static and dynamic typing. We present a system that permits a value of dynamic type to be cast to a polymorphic type and vice versa, with relational parametricity enforced by a kind of dynamic selaing along the line proposed by Matthews and Ahmed (2008) and Neis, Dreyer, and Rossberg (2009). Our system includes a notion of blame, which allows us to show that when casting between a more-precise type and a less-precise type, any failure are due to the less-precisely-typed portion of the program. We also show that a cast from a subtype to its supertype cannot fail.

The Arrow Calculus

2010-11-30T17:57:00.003Z

The arrow calculus, Sam Lindley, Philip Wadler, and Jeremy Yallop, Journal of Functional Programming 20(1):51-69, 2010.

We introduce the arrow calculus, a metalanguage for manipulating Hughes’s arrows with close relations both to Moggi’s metalanguage for monads and to Paterson’s arrow notation. Arrows are classically defined by extending lambda calculus with three constructs satisfying nine (somewhat idiosyncratic) laws; in contrast, the arrow calculus adds four constructs satisfying five laws (which fit two well-known patterns). The five laws were previously known to be sound; we show that they are also complete, and hence that the five laws may replace the nine.

A list is an odd creature, take 5

2010-11-29T11:02:00.003Z

And a fifth entry in the stakes to illustrate a list, or at least recursion. Thanks to Mitchell Wand, who found the original here.

A list is an odd creature, take 4

2010-11-26T18:33:00.004Z

A fourth entry in the stakes to illustrate a list. Thanks to Eugene who posted this item from Cyriak's collection (click here for the animated version):Previous entries:

Mandelbrot Maps - now on an album near you

2010-11-17T11:42:00.002Z

Mandelbrot Maps was written by Iain Parris as an MSc project, and updated by Edward Mallia and Taige Liu. (Here's the original.) Jim Hanks used it to generate the cover for his latest album Dedication. That's a nice recognition of Ian, Edward, and Taige---well done, folks!

A list is an odd creature, take 3

2010-11-02T16:27:00.005Z

I mentioned to my first-year students that a list is an odd creature: it has only a head and a tail, where the tail is itself a creature with only a head and a tail, and so on. I challenged them to produce a picture, and Dan Benveniste came up with this:

I like the recursion, but it's not really a creature, is it? Further attempts encouraged! Previous entries:

Science is Vital

2010-09-23T16:30:00.004+01:00

My colleague, Maria Wolters, writes:

I'd also like to mention the Science is Vital campaign, which is orchestrated by biomedical researchers but aims to be as inclusive as possible. There will be a march in London on October 7, a letter writing campaign, and potentially much more ... I know it's incredibly tempting not to do anything because politicians don't listen anyway, but if we don't complain loudly enough now, we might as well stick a sign on our backs saying "Doormats - If You Need Funds, Take Them From Us."

Portsmouth Sinfonia

2010-09-23T10:08:00.003+01:00

A colleague recently referred to EPSRC's approach of appointing program managers untrained in the areas they manage as like the Portsmouth Sinfonia.

Twelve Virtues of Rationality

2010-09-22T13:14:00.002+01:00

"These then are twelve virtues of rationality: Curiosity, relinquishment, lightness, evenness, argument, empiricism, simplicity, humility, perfectionism, precision, scholarship, and the void." By Eliezer S. Yudkowsky. Spotted via Conal Elliott. Thanks for the tip, Conal, it's a great read.

ed lambda Meetup

2010-09-10T09:36:00.004+01:00

For those of you in or near Edinburgh: 7pm Monday 13 September 2010, Malone's Irish Bar, 14 Forrest Road. How to find us: "Look out for the lambda on the table". Organized by Ollie Saunders.

What Sequential Games, the Tychonoff Theorem and the Double-Negation Shift have in Common

2010-08-30T17:55:00.003+01:00

A recent paper by Escardo and Oliva, to appear in MSFP 2010, relates diverse aspects of computing, in the form of a literate Haskell program. I've written a further note inspired by theirs, also as a literate Haskell program. My code improves on theirs in a few ways, notably by using type classes to characterize valuation types, and by using QuickCheck to describe and check relevant properties. My note can be read stand-alone, but is best read in conjunction with Escardo and Oliva's paper. (The photo above is Cantor Set by Kevin van Aelst.)

Does Your Language Shape How You Think?

2010-08-30T15:09:00.003+01:00

From an article in the New York Times by Guy Deutscher, describing linguistics view of the Sapir-Whorf hypothesis, seventy years on. Taken from his book Through the Language Glass: Why the World Looks Different in Other Languages. Spotted on Lambda the Ultimate.

For instance, some languages, like Matses in Peru, oblige their speakers, like the finickiest of lawyers, to specify exactly how they came to know about the facts they are reporting. You cannot simply say, as in English, “An animal passed here.” You have to specify, using a different verbal form, whether this was directly experienced (you saw the animal passing), inferred (you saw footprints), conjectured (animals generally pass there that time of day), hearsay or such. If a statement is reported with the incorrect “evidentiality,” it is considered a lie. So if, for instance, you ask a Matses man how many wives he has, unless he can actually see his wives at that very moment, he would have to answer in the past tense and would say something like “There were two last time I checked.” After all, given that the wives are not present, he cannot be absolutely certain that one of them hasn’t died or run off with another man since he last saw them, even if this was only five minutes ago. So he cannot report it as a certain fact in the present tense.

I wish all scientists were trained in this language!

L'Illusionniste

2010-08-26T18:52:00.005+01:00

L'Illusionniste, Sylvain Chomet's second film and Jacques Tati's last, is a remarkable film; The Guardian gave if five stars. The film also reflects a tortured family history. Among other things, it is a love letter to Edinburgh, with loving depictions of many familiar locations. I saw it in the Cameo; how often do you watch a film that includes a scene in the very place you are sitting? While many of the settings are easy to identify, I could not place one key location, the 'Royal Music Hall' (see below)---did this actually exist in Edinburgh, and if so, where?

The Economics of Programming Languages

2010-08-26T18:44:00.004+01:00

Network effects are clearly significant in the spread of programming lagnuages. I've often thought it would be good to team up with an economist to see if one could say something more forceful than just that simple qualitative observation. Meanwhile, I'm pleased to find the web page linked to above, which covers at least the obvious correspondences. (NB., the picture is from a different page.)

Programming Language Popularity

2010-08-26T18:32:00.002+01:00

A site that tracks popularity of Programming Languages. Many of my favorite languages appear on the list. Interesting to see that (for this week at least) the order is Scheme, Haskell, Smalltalk, Erlang, Scala, O'Caml.

Sights and sounds of sorting

2010-08-24T20:34:00.003+01:00

Nifty visualisation with sound of several sorting algorithms. It covers insert, bubble, selection, merge, and gnome sort; a related video tackles heap sort. Could be useful for teaching. Below is a second visualisation with robots.

Masterminds of Programming wins JOLT award

2010-08-11T15:04:00.003+01:00

Masterminds of Programming, edited by Federico Biancuzzi and Shane Warden, has just won a Jolt award. The book features interviews with the creators of many programming languages, including a chapter on Haskell with contributions from Paul Hudak, John Hughes, Simon Peyton Jones, and myself.

The Bull, the Bear, and the Python (Part 2)

2010-08-03T10:40:00.002+01:00

A previous post described the SEC's plan to clarify certain kinds of trades by describing them using a computer program, written in Python. Responses to the SEC's request for comments are now online, including a response jointly submitted by USACM and SIGPLAN. My thanks to all the experts who volunteered to help us formulate a response and ensure it represented the views of the USACM and SIGPLAN membership.

Visualization of Natural Deduction as a Game of Dominoes

2010-07-01T09:53:00.002+01:00

The usual Gentzen-style rules make some use of visual layout, but I suspect it may be possible to exploit the potential of graphical techniques far more effectively. Here is one attempt to do so. I'm not entirely convinced by this particular approach, but it is a brave attempt and worth noting.

Information is Beautiful: How Will The Budget Impact the Deficit?

2010-06-29T09:16:00.004+01:00

A stunning Infographic from David McCandless of Information is Beautiful. Note the £1 billion raise in capital gains compared to the £13 billion raise to VAT. An interesting perspective on these comments is offered by Joseph Stiglitz. Spotted via Boing Boing.

Why Undergraduates Should Learn the Principles of Programming Languages

2010-06-24T15:40:00.004+01:00

SIGPLAN's Education Board has produced a document describing why undergraduate education in programming languages is essential. It's aimed at academics who are not specialists in programming languages. Please read and comment to help SIGPLAN improve it!

Monster Chess Lego Robots

2010-06-18T17:33:00.001+01:00

Spotted by Stuart Beard. Thanks, Stuart!

Functional Programming – Crossing The Chasm?

2010-06-01T11:26:00.001+01:00

A column by Dave Thomas (left) in the Journal of Object Technology.

Sausalito, CAP

2010-05-19T11:51:00.002+01:00

Catching up on the DB world. Learned of Sausalito from my old colleague Dana Florescu. Read Developing an Enterprise Web Application in XQuery and Building a Database on S3. Also read a description of the CAP Theorem.

The Bull, the Bear, and the Python

2010-04-22T15:53:00.005+01:00

In the US, the SEC plans to use programs to clarify complex trades by expressing them as a computer program. This strikes me as a fine idea, but they also require the use of Python. This is much better than the worst they could do, but also much worse than the best. A description of the plans, with further links, is posted by IT World and a critique is posted by Untyped.

Functional languages have recently seen increased use in the financial industry, including Jane Street Capital, Standard Chartered, and Credit Suisse. Of particular interest is work on composing financial contracts in functional languages, as pursued by LexiFi. I don't know how well this work could transpose to Python.

It has been proposed that SIGPLAN file a response to the SEC's request for comments. I am interested to hear the views of the programming language community. Should we support Python? Or should we suggest alternatives to Python, and, if so, what should we point the SEC towards?

Object and Representation

2010-04-21T10:13:00.002+01:00

"Alexa Meade, 23, is a Washington, DC-based artist who paints on top of her subjects and puts them in real life settings. (No, you can't see the pixels. This is real.) From Meade's artist statement:

"'The reverse trompe l'oeil series is Alexa Meade's spin on reality. Alexa has invented a painting technique that makes 3 dimensional space look flat, blurring the lines between illusion and reality.

"'Typically a painting is an artist's interpretation of the subject painted onto another surface. In Alexa's paintings, she creates her artistic interpretation of the subject directly on top of the subject itself. Essentially, her art imitates life - on top of life.'"

Spotted via Boing Boing, which is the source of the above quote.

Eyjafjallajokull

2010-04-20T14:34:00.002+01:00

Programming language researchers are among those dislocated by the flight ban caused by the eruption. FLOPS in Japan was seriously disrupted, and Barbara Liskov was forced to extend her visit to Edinburgh (where she spoke at the BCS/ACM Visions conference) so I had the benefit of a tutorial on distributed programming from her this morning.The ash plume of southwestern Iceland's Eyjafjallajokull volcano streams southwards over the Northern Atlantic Ocean in a satellite photograph made April 17, 2010. The erupting volcano in Iceland sent new tremors on April 19, but the ash plume which has caused air traffic chaos across Europe has dropped to a height of about 2 km (1.2 mi), the Meteorological Office said. (REUTERS/NERC Satellite Receiving Station, Dundee University, Scotland)Lava and lightning light the crater of Eyjafjallajokul volcano on April 17, 2010. (REUTERS/Lucas Jackson)

Apple bans Scratch from iPhone and iPad

2010-04-16T12:43:00.005+01:00

Apple has locked down the iPhone and iPad to a tiny set of languages (C, C++, Objective C, and Javascript), and has followed up by banning interpreters for the child-friendly programming language Scratch. A black day for programming language designers.

RADICAL 2010

2010-04-14T19:33:00.002+01:00

RADICAL 2010, International Workshop on Relations and Data Integrity Constraints and Languages. May 10-11, 2010, Microsoft Research, Cambridge, UK.

RADICAL is a workshop on databases and programming languages, with an emphasis on connections between databases and recent advances in type systems and logics, especially dependent type systems incorporating data constraints.

Organising committee:
* Andrew D. Gordon (convenor), Microsoft Research
* David Langworthy, Microsoft Corporation
* Philip Wadler, University of Edinburgh

Check out the web page, and drop us a line if you'd like to attend.

Robin Milner, 1934--2010 (second update)

2010-04-14T10:21:00.002+01:00

A third obituary, written by Michael Fourman, has appeared in The Independent.

Digital Economy Bill

2010-04-05T14:44:00.002+01:00

The Digital Economy Bill is slated to receive it's second reading on Tuesday 6 April, the day the government plans to call for election. This timing will enable it to go into a 'wash up', a process by which bills are approved on the action of the whips alone without scrutiny by MPs. Controversial parts of the bill could be rushed through with as little as 90 minutes of debate. This is particularly disturbing because of the bill's effect on civil liberties.

The bill's 'three-strikes' provision would allow an entire family to be disconnected because a teenager downloaded songs or videos in violation of copyright, without due process in the courts. The same provision may make it difficult for internet cafes, hotels, or universities to allow internet access. The bill also could make it difficult to offer any website that stores material for users, since in theory the stored material may violate copyright. Provisions of the bill may also be used to shut-down public interest websites such as WikiLeaks (which publishes leaked, and hence copyrighted, work).

A detailed description of how your service could be cut off is given by Digital Wrong. An assessment of the civil rights implications is given by Liberty. An article summarizing the bill appears in The Guardian. Organizations campaigning against the bill include Open Rights Group and 38 Degrees. The latter link takes you to a web application that will allow you to send an e-mail to your MP in only a few minutes.

Robin Milner, 1934--2010 (update)

2010-04-02T17:13:00.001+01:00

A second obituary has appeared in the Guardian.

Robin Milner, 1934--2010

2010-03-31T11:42:00.002+01:00

An obituary has appeared in the Times. I believe others will appear shortly.

LaTiKi, a Wiki for LaTeX

2010-03-09T23:35:00.002Z

Stuart Beard has been developing LaTiKi, a Wiki for LaTex, as a UG4 project under my supervision. He writes as follows:

I am pleased to announce that LaTiKi is now available as a public beta.

LaTiKi accepts LaTeX syntax as input rather than the wiki syntax that is standard across many wiki implementations. This Wiki enables LaTeX users to collaborate on papers, edit, and track each paper. It is entirely based upon the open-source and widely used platform MediaWiki. I am looking for interested users to contribute, try out how well the system works and how useful the system really is. I also hope that any major underlying bugs are identified.

I have prepared a sandbox wiki with some of Philip Wadler's papers on the site to demonstrate how the system works. Note that to be able to edit papers on the sandbox you MUST sign up to the site and confirm your email address. This is available at http://www.stuartbeard.com/wiki.

Feedback is greatly appreciated.

If any readers are interested in this project and would like to do a similar thing with their own papers then a tarball is available at http://www.stuartbeard.com/projects.

Dimensions

2010-02-01T10:05:00.003Z

Brilliant math videos. Adam and Leora had a look at the first last night, and were impressed. (It takes a lot to impress two ten-year olds!) Thanks to Perdita Stevens for pointing me at these.

Self-Description

2010-02-01T09:51:00.002Z

(Be sure to read the mouse-over.) Imagine the applications to cryptography! From XKCD, a webcomic of romance, sarcasm, math, and language, by Randall Munroe.

Burns night

2010-01-25T16:28:00.002Z

Two videos of the Informatics Burns night. Thanks to Steve Ewing for the oration, and to Andrew Mitchell for the videos.

Designing Effective Action Alerts

2010-01-12T09:30:00.001Z

By Phil Agre. Sensible advice, crafted by someone who knows. Thanks to my colleague Conrad Hughes for pointing this out.

Climategate

2009-12-24T15:33:00.005Z

Three references I've found useful on Climategate:

George Monbiot: Pretending the climate email leak isn't a crisis won't make it go away

George Monbiot: The climate denial industry is out to dupe the public. And it's working

Marc Sheppard: Understanding Climategate's Hidden Decline

The last is by a climate change denier, but contains the only clear explanation I've seen of what the leaked e-mails refer to as "Mike's Nature Trick". Anyone know of an explanation from a more reputable source? Or what current science makes of what the first IPCC report referred to as the "Medieval Warming Period"?

Time management: How an MIT postdoc writes 3 books, a PhD defense, and 6+ peer-reviewed papers — and finishes by 5:30pm

2009-12-24T14:48:00.003Z

Cal Newport, a post-doc at MIT who writes the blog Study Hacks, has an interesting method of getting important work done. He calls it "fixed-schedule productivity." The idea is easy to understand, but perhaps harder to execute: determine your goals, and focus on those, not the myriad interruptions that arise each day. Perhaps a resolution for the new year? (Spotted via Boing Boing.)

Happy Chanukah!

2009-12-14T09:17:00.006Z

Tony Karom, quoted by JfJfP:

In a country occupied by a Western power, the locals are faced with a choice. Some have opted to reconcile their own traditions with those of their occupier, borrowing from Western ways that open the path to philosophy and science, and integrating themselves into a wider culture. Others fiercely resist, waging a bitter and bloody war not only on the occupier, but also on those in their own community who seek to collaborate or integrate with the occupiers who are denounced as defilers.

If this were contemporary Afghanistan-Pakistan, you’d know who was whom, right? But before you bite into that latke or sing the dreidel song, you may want to consider that in Judea in the second century BC, the Taliban role is played by the Maccabees. And it is the Maccabees, of course, who are lionized in the Hanukah tale.

In fact, they pretty much invented the holiday to celebrate their victory over the Greeks and all Jews who would embrace their ways, the “Hellenizers.” Hanukah is not mentioned in the Torah. It’s not really a religious holiday at all — the bubbemeis about an oil lamp burning for eight days was tacked on as an afterthought, and a way of smuggling God into what was a ritual celebrating a very temporal insurgent military triumph.

There is, of course, a spectacular irony in the celebration of Hanukah in its contemporary incarnation as a kind of kosher Christmas that has everybody saying “Happy Holidays” to avoid giving offense. The irony, of course, is that celebrating Hanukah as a major religious holiday is the ultimate triumph of latter-day Hellenization. It hardly exists as a serious religious holiday — even when I was growing up in South Africa, the likes of Simchat Torah and Succoth were far more important. Yet today, in America, it appears to rank up there right after Rosh Hashana/Yom Kippur and Passover as important Jewish holidays. The point, of course, is that this has only been done to compete with Christmas, to adapt Jewish tradition to make it fit the rhythms and rituals of the wider, non-Jewish society.

(Image: Maccabees vs. Hellenists Chess Set.)

Computer Science Education Week

2009-12-11T11:37:00.002Z

This week was declared Computer Science Education Week by the US Congress. I heard when the declaration was made a couple of months ago, but heard nothing at all this week. Anyone across the pond care to comment on how it is preceding? Getting the public to understand that computing is an academic discipline rather than just a technology on their desks and in their pockets is a vital task, and this week is one of our best opportunities to accomplish that.

National Petition for Libel Law Reform

2009-12-11T11:26:00.003Z

The recent Ben Goldacre case and ongoing Simon Singh case show that Enlish libel laws threaten the free and public conduct of science. Sense about Science has joined with English PEN and Index on Censorship to launch a National Petition for Libel Law Reform

A list is an odd creature, take 2

2009-11-20T11:38:00.003Z

A second entry, from Timothy Abraham.

I have created this animal which represents a list, it's a snake whose tail consists of heads, in the end you'll see that the snake releases air with the empty list in it, this symbolizes the empty list, because the empty list is like air it is something but it is also nothing.

Visualizing Empires Decline

2009-11-18T11:24:00.002Z

An elegant animation by Pedro M Cruz. Spotted via Boing Boing.

Ditto

2009-11-18T09:41:00.002Z

A new Internet meme.

A list is an odd creature

2009-11-17T10:44:00.005Z

I have just remembered your request for a picture of a creature, with lots of heads and a tail.

The closest to this I was able to come up is a shark eating another shark eating ... etc.

Let's think of shark's head as an element in the list. This way one could think of ":" as shark teeth 'connecting' to other shark (Cons even look like a mark from a bite!). Then the head of the smaller shark is the head of new list, and the tail of the list is the bigger shark.

If we assume that water is [], then it also works in the bottom case with no elements in the list (no sharks) - only water. And water swallows the shark up to it's head so this also work (shark : []).

Mandelbulb

2009-11-17T10:34:00.005Z

The quest for the 3D-analogue of the Mandelbrot curve, with some remarkable photos. Passed on by my colleague Bob Fisher, who knew of my work with students on interactive application, Mandelbrot Maps. Thanks, Bob!

Transforming the Academy: Knowledge Formation in the Age of Digital Information

2009-11-10T18:48:00.003Z

My favorite quote from Edsger Dijkstra comes from his Turing Award Lecture, The Humble Programmer:

"In their capacity as a tool, computers will be but a ripple on the surface of our culture. In their capacity as intellectual challenge, they are without precedent in the cultural history of mankind."

I've just listened to the best defense of this thesis that I've ever heard, courtesy of Bob Constable. A paper on the same topic of his is linked above.

Other relevant papers on the same subject are Alan Bundy's Computational Thinking is Pervasive and Jeanette Wing's Computational Thinking.

I was also fortunate to see Jeanette Wing address this topic in her recent OOPSLA keynote. In the question period, I mentioned Dijkstra's quote, and also my interpretation of it. I believe that in his usual style, Dijkstra was exaggerating. I think there are two precedents: the invention of writing and the discovery of mathematics. Computing give us, with prose and mathematics, a third way to describe our discoveries.

Cell size and scale

2009-11-10T09:17:00.002Z

A web app from the University of Utah, reminiscent of the Eames' Powers of 10 movie. It covers microscale but not macroscale. Any web apps that cover the opposite?

Conference Collected Wisdom Wiki

2009-10-14T10:31:00.000+01:00

One output of WOWCS (the Workshop on Organizing Workshops, Conferences, and Symposia for Computer Systems) is a wiki to collect information on organizing conferences. I haven't looked at it in detail yet, but I'm putting the link here for future reference. Collecting experience in this way sounds like a good idea to me.

Robin writes a book (and you get a copy)

2009-10-14T10:29:00.000+01:00

Here is your chance to be a patron of the arts. Robin Sloan, the author of Mr. Penumbra (see earlier blog entry), is writing a book. Sponsor him, and you get a copy and updates on the book's progress. Progress reports include use of Google ad-words to choose the lead character's name, and a short story about flying written during a flight from San Francisco to New York.

Mr. Penumbra’s Twenty-Four-Hour Book Store

2009-09-23T14:43:00.003+01:00

William Gibson stopped setting his novels in the future, saying that the present had caught up with science fiction. Another illustration is this intriguing fantasy from Escape Pod, written by Robin Sloan and read by Stephen Eley. The story originated in a misread twitter, and was published on a blog, and adapted for this podcast.

Mr. Penumbra has a database, believe it or not. The books aren’t shelved according to title or subject (do they even have subjects?) so the database is crucial. It runs on an old Mac Plus, but I copied it onto my laptop and, over the course of a few customer-free nights, mapped it onto a 3D model of the store. (If this sounds impressive to you, you’re over 30.)

I was intrigued by the author's vision of the Google campus.

And while I'm at it, let me heartily commend Escape Pod itself, my favorite thing to listen to while doing the ironing. I'm slowly working through their back catalogue of two hundred stories.

Peter Landin obituary

2009-09-23T14:36:00.003+01:00

Olivier Danvy delivered a lovely memorial to Peter Landin at this year's ICFP, but it was light on some of Landin's politics. Richard Bornat penned this excellent remembrance for the Guardian.

Wandering through linear types, capabilities, and regions

2009-08-28T13:21:00.003+01:00

A survey by François Pottier, which links a number of concepts and clarifies a cluttered landscape. Spotted via LtU.