Fun

Every language you never wanted to know

The Virtual Unknowns (alternative link - apparently the one I gave earlier may expire)
(hope this works; not posted to this version of the site before, so apologies if this is broken in some way...)

Erlang the Movie


From: mike@erix.ericsson.se (Mike Williams)
To: erlang-questions@erlang.org

[...]

As one of the main "actors" in "Erlang the Movie", I
absolutely and categorically forbid its showing *anywhere*. If there
was a competition for "turkey" short movies, I think we would win
hands down.

So, please, please, please, forget we made that retched film in 1990!

That's right, now you too can own the movie that "Bjarne used whenever he wanted to get rid of unwanted guests at CS lab parties"! Download the torrent or the file on erlang.org if you have 200MB of disk space to spare!

No, no and again, NO!!!

Reflections on reflection - Henk Barendregt

(Link)

Here's something to exercise both brain hemispheres. Henk Barendregt needs no introduction for many LtU readers - he literally wrote "the book" on the lambda calculus, and that only hints at the profound impact his work has had on lambda calculus and type theory.

The page linked above lists two overlapping papers, both about reflection:

Reflection plays in several ways a fundamental role for our existence. Among other places the phenomenon occurs in life, in language, in computing and in mathematical reasoning. A fifth place in which reflection occurs is our spiritual development. In all of these cases the effects of reflection are powerful, even downright dramatic. We should be aware of these effects and use them in a responsible way.

A prototype situation where reflection occurs is in the so called lambda calculus. This is a formal theory that is capable of describing algorithms, logical and mathematical proofs, but also itself.

As the first paragraph quoted above implies, the scope of these two papers extends far beyond the lambda calculus, into fields such as biology and meditation. Between the two papers, there's something for everyone:

"Reflection and its use, from science to meditation" is wide-ranging, covering reflection related to living cells, formal languages, mathematics, art, computers, and the human mind.

"Reflection and its use, with an emphasis on languages and lambda calculus", focuses specifically on reflection in formal languages, including combinatory logic and lambda calculus.

Richard Feynman and the Connection Machine

by way of lemonodor

An entertaining article by Danny Hillis about Richard Feynman's work at Thinking Machines Corporation on the Connection Machine.

We've mentioned the Connection Machine's data-parallel programming style on LtU before, and Connection Machine Lisp remains my all-time favourite paper in computer science.

Functional programming with GNU make

One of the gems squirreled away on Oleg's site is "Makefile as a functional language program":

"The language of GNU make is indeed functional, complete with combinators (map and filter), applications and anonymous abstractions. That is correct, GNU make supports lambda-abstractions."

Although I've classified this under Fun, Oleg exploits
the functional nature of Make for a real, practical application:

"...avoiding the explosion of makefile rules in a project that executes many test cases on many platforms. [...] Because GNU make turns out to be a functional programming system, we can reduce the number of rules from <number-of-targets> * <number-of-platforms> to just <number-of-targets> + <number-of-platforms>."

See the article for a code comparison
between make and Scheme, and check out the Makefile in question.

Tunes create context like language

This article discusses the extension of the notion of context from linguistics to the domain of music. In language, the statistical regularity known as Zipf's law -which concerns the frequency of usage of different words- has been quantitatively related to the process of text generation. This connection is established by Simon's model, on the basis of a few assumptions regarding the accompanying creation of context. Here, it is shown that the statistics of note usage in musical compositions are compatible with the predictions of Simon's model. This result, which gives objective support to the conceptual likeness of context in language and music, is obtained through automatic analysis of the digital versions of several compositions. As a by-product, a quantitative measure of context definiteness is introduced and used to compare tonal and atonal works.

Related Nature article.

From Gyan on Metafilter.

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