Lambda the Ultimate

Luke Palmer and Nick Szabo can shoot me for this if they want, but I think this is warranted, and I want to connect a couple of dots as well. Luke is one of a number of computer scientists, with Conal Elliott probably being the best known, who have devoted quite a bit of attention to Functional Reactive Programming, or FRP. FRP has been discussed on LtU off and on over the years, but, unusually for LtU IMHO, does not seem to have gotten the traction that some other similarly abstruse subjects have.

In parallel, LtU has had a couple of interesting threads about Second Life's economy, smart contracts, usage control, denial of service, technical vs. legal remedies, and the like. I would particularly like to call attention to this post by Nick Szabo, in which he discusses a contract language that he designed:

Designing the contract language radically changed my idea of what program flow and instruction pointers can be. Its successor, a general-purpose programming language, may thereby make event-oriented programming and concurrency far easier. The language is targeted at GUI programming as well as smart contracts, real-time, and workflow programming. My answer to the problems of concurrency and event handling is to make the ordering of instructions the syntactic and semantic core of the language. The order of execution and event handlers are the easiest things to express in the language rather than kludged add-ons to a procedural or functional language.

In recent private correspondence, Nick commented that he'd determined that he was reinventing synchronous programming à la Esterel, and mentioned "Reactive" programming.

Ding!

To make a potentially long entry somewhat shorter, Luke is working on a new language, Dana, which appears to have grown out of some frustration with existing FRP systems, including Conal Elliot's Reactive, currently perhaps the lynchpin of FRP research. Luke's motivating kickoff post for the Dana project can be found here, and there are several follow-up posts, including links to experimental source code repositories. Of particularly motivating interest, IMHO, is this post, where Luke discusses FRP's interaction with garbage collection succinctly but nevertheless in some depth. Luke's most recent post makes the connection from Dana, which Luke has determined needs to have a dependently-typed core, to Illative Combinatory Logic, explicit, and offers a ~100 line type checker for the core.

I find this very exciting, as I believe strongly in the project of being able to express computation centered on time, in the sense of Nick's contract language, in easy and safe ways extremely compelling. I've intuited for some time now that FRP represents a real breakthrough in moving us past the Von Neumann runtime paradigm in fundamental ways, and between Conal Elliott's and Luke's work (and no doubt that of others), it seems to me that my sense of this may be borne out, with Nick's contract language, or something like it, as an initial application realm.

So I wanted to call attention to Luke's work, and by extension recapitulate Conal's and Nick's, both for the PLT aspects that Luke's clearly represents, but also as a challenge to the community to assist in the realization of Nick's design efforts, if at all possible.

Registration for the International Lisp Conference 2009 is now open. For a quick summary, see the announcement posted by conference chair Dan Weinreb.

The keynote speakers may be of interest to LtU readers: Gerald Jay Sussmann, Shriram Krishnamurthi, and David Moon.

The conference is at MIT from March 22 to 25. Early registration is a very reasonable $210 ($75 for students).

The notes from a panel held at POPL 2009 on this topic are available here.
The panelists were Simon Peyton Jones, Kathryn McKinley, Xavier Leroy, Martin Rinard and Greg Morrisett.

Among the topics raised: Effects, Program verification, Parallelism, Visualization tools for understanding behavior of parallel programs, Secure software, High assurance.

Not surprisingly all these topics have been discussed here repeatedly in recent years...

McCarthy's Elephant language proposal was mentioned here several times in the past. This talk from Etech provides a nice introduction to the fundamental idea behind Elephant and its background.

The talk includes interesting, though not entirely motivated, comments related to the paper Ascribing Mental Qualities to Machines. This is one of McCarthy's most significant papers in my opinion, and deserves more attention and debate. It is also rather amusing. I hope I will find the time some day to put this paper in context (McCarthy's comments in the Etech talk notwithstanding), but for the time being I recommend it to anyone interested in this sort of thing.

One thing is for sure: We can safely add to the 2009 predictions the prediction that Elephant will not be ready in 2009...

In the history of PL design there has been quite a bit of vitriol spilled over design choices. These days bringing up "static vs dynamic typing" is a good way to generate some heat on a cold winter web forum.

But a few debates seem to have been pretty firmly resolved, at least for general purpose languages. GP languages have considered goto harmful for decades now, dynamic scoping is seen as a real oddity, and manual memory management is a choice only made by systems language designers.

Questions for LtU: What other debates have been "resolved" in the sense that general purpose languages are hardly ever designed with an alternative to the consensus? What debates will be resolved in the near future? And what apparently resolved debates deserve to be reopened?

One rule: "static vs dynamic typing" will be considered off topic because clearly and emphatically that debate hasn't been resolved and has no prospect of being resolved any time soon. Also, it's boring.

The New York Time says Data Analysts Captivated by Power of R.

R is ... the name of a popular programming language used by a growing number of data analysts inside corporations and academia. It is becoming their lingua franca partly because data mining has entered a golden age, whether being used to set ad prices, find new drugs more quickly or fine-tune financial models. Companies as diverse as Google, Pfizer, Merck, Bank of America, the InterContinental Hotels Group and Shell use it.

Hmmm, "fine tune financial models". Does R stand for Recession?

More seriously, does data mining plus multi-core machines add up to an important language direction for the next few years? How well does R fare on such boxen?

More on R previously on LtU here and here.

With 2008 winding to a close, here's a question to you: what was noteworthy about 2008 as far as programming languages were concerned? To paraphrase Ehud, on topic are notable news about PLT research (direction, fads, major results) (2) notable news about programming languages (whether about specific languages, or about families etc.) and (3) notable news about industrial use of languages/language-inspired techniques (adoption, popularity).

While we're at it, let's score the predictions made at the beginning of the year and laugh at how young and naive we once were or at least make excuses about why our foretelling didn't quite pan out as predicted.

An introductory overview article about static analysis tools and how they can be used to improve software security. The article talks a bit about the history of Cigital's ITS4 tool.

Via Patrick (who was once a LtU contributor), two interesting blog posts:

• A discussion of the uses of Lua in Lightroom and about the use of dynamic language to develop desktop software in general (blog post by a LtU member). Apparently, some 63% of the code written by the Adobe Lightroom team is in Lua.
• A brief history of IBM's Visual Age, originally written in Smalltalk (the product, not the blog post), and Digitalk (remember Digitalk?!).

A nice viedo interview of Anders Hejlsberg and Guy Steele on Concurrency and Language Design at the JAOO conference. Nothing too technically deep, but the interview does manage to crystalize some of the high level issues that face language designers.

Speaking of interviews, the Lisp50 Conference at OOPLSA 2008 will have what should prove interesting - Alan Kay interviewing John McCarthy.