Lambda the Ultimate

As a follow up to the previous post, check out how Chung-chieh Shan applied regions to a seemingly unrelated problem. His post begins by explaining how automatic (numerical) partial differentiation can be implemented, and goes on to show how to use regions to avoid mixing-up the variables being differentiated.

Just a quick reminder -- the 2008 ICFP Programming Contest starts tomorrow.

Maker Faire was fun, but you can read all about it on numerous web sites and blogs. While I enjoyed the Coke + Mentos demonstration like everyone else, some things caught my eye in particular and may also amuse LtU readers.

Talking to the guys demoing the CNC machines I discovered G Code which turns out to be the main machine languages used to control the CNC machines. It was cool to meet people who actually wrote their own software to emit or/consume G codes (the styrofoam CNC machine was way cool).

I also enjoyed The Art of Motion Control sculpture, since the text said "Path designs using custom LISP routines running within AutoCAD." I think that was the only one explicitly mentioning Lisp. At least, that was the only one I saw...

Any cool language references I missed?

Conrad Barski has posted a sneak peak from his upcoming Lisp textbook/comic: Land of Lisp.

The first slides may seem unrelated, but boy does the message sting when you reach the ending...

FPers will be quick to note, of course, that this being April Fools' Day the whole thing is a joke and we can all go back to Haskell...

You can get soup in a can. You can get bread in a can. Now the long wait is over! You can finally get Lambda Calculus in a can...Project LambdaCan takes [the Lambda Calculus] and implements it on a microcontroller better suited to the most mundane of tasks, like running a vending machine or microwave oven. And it sticks the microcontroller in a can that you can connect to your PC using a USB cable.

For those that are both language geeks and hardware geeks...

A Dialogue on Infinity, between a mathematician and a philosopher. Alexandre Borovik and David Corfield.

A new blog... From the first post:

The project concentrates on one of the principal purposes of the Exploring the Infinite Program:

To understand the nature of and the role played by conceptualizations of infinity in mathematics.

It will be shaped as a dialogue between a mathematician (AB) and a philosopher (DC) and will address one of the central paradoxes of mathematics:

why are most uses of infinity in mathematics restricted to the recycling of a small number of “canonical” and ubiquitous structures?

...To put the study of infinity on a firm basis, we first have to discuss the issue of the identity and “sameness” of mathematical objects: infinity of what?

This is pretty far out for LtU, but I suspect it will interest some more philosophically inclined readers. They will look at a number of disciplines, including computer science.

(I feel like maybe even "Theory" is not theoretical for this. Therefore I am also calling it "Fun".)

While Anton was waxing about Church & Turing, I figured that Occam's Razor would be the type of proof one would postulate when giving the nod to Lambda Calculus over Universal Turing Machines. This leads inexorably to the question of what is the smallest (as measured in binary bits) Turing Machine that can possibly be constructed. John Tromp provides an answer to this question in his always fun Lambda Calculus and Combinatory Logic Playground:

Pictured you can see the 210 bit binary lambda calculus self-interpreter, and the 272 bit binary combinatory logic self-interpreter. Both are explained in detail in my latest paper available in PostScript and PDF. This design of a minimalistic universal computer was motivated by my desire to come up with a concrete definition of Kolmogorov Complexity, which studies randomness of individual objects. All ideas in the paper have been implemented in the the wonderfully elegant Haskell language, which is basically pure typed lambda calculus with lots of syntactic sugar on top.

Interestingly, the version based on the Lambda Calculus is smaller than the one on Combinators. A statement I found of interest in the paper about PL's:

Although information content may seem to be highly dependent on choice of programming language, the notion is actually invariant up to an additive constant.

Not sure if that statement means that PL research is ultimately doomed. :-)

One of the great things about LtU discussions is that we have some very witty posters, and some posts are LOL funny (that's "laugh out loud" for those new to the internet...)

So I decided to start an informal poll here: which is the funniest post on LtU ever?

I suggest two categories: one for general humour and wit, and a second for humour that requires knowledge of the theory of pogramming languages to decipher.

On edit: I think we need a special category for longer, more literary posts, if you will - the type Frank used to produce.

On the off-chance you hadn't realized it, the 2007 ICFP contest has started today. Join the fun!

The date and venue for AngloHaskell 2007 have been finalised and announced:

We are pleased to announce AngloHaskell 2007

http://www.haskell.org/haskellwiki/AngloHaskell

Dates: 10th-11th of August (Friday-Saturday)
Location: Cambridge, with talks at Microsoft Research on Friday

All the details are on the wiki page, along with free registration.
Everyone is invited, we will have a day of talks at MSR, then a day of
other activities. There will be plenty of chance for general
discussions on anything.

If anyone in Cambridge is able to accommodate a few people for the
Friday or Saturday night, please add your name to the wiki, and accept
our thanks in advance. All that is needed is floor space.

Thanks

Neil and Philippa

LtUers are all welcome - especially anyone who wants to give a talk! As Neil put it in a previous mail:

This is NOT an academic conference. Everyone is welcome to attend, there is no fee. Everyone is invited to offer a talk.

Practical talks are particularly welcome. I'll be giving a talk on my experiences with Haskell as a person with Asperger's Syndrome.