Lambda the Ultimate

Frege's Contribution to Philosophy of Language. Richard G. Heck and Robert May. Forthcoming in the Oxford Handbook of Philosophy of Language, edited by E. Lepore and B. Smith.

An investigation of Frege's various contributions to the study of language, focusing on three of his most famous doctrines: that concepts are unsaturated, that sentences refer to truth-values, and that sense must be distinguished from reference.

Warning: This isn't directly related to programming languages. In fact, if you haven't studied Frege this paper might be quite puzzling.

While not directly programming language related, I still think this paper might be of interest. Frege is quite an important figure in the history of logic, of course, and as we all know logic and computation are very much related to each other.

In addition, this paper deals with the notions of function and predicate, and these notions are part of our standard terminology. Reading this paper might improve our understanding of these notions and their history, as well as the notions of equality vs. identity, and intensional vs. extensional view of functions (see the end of section 4).

So if Java is a victory for Smalltalk’s implementation choices, and Ruby is a victory for Smalltalk’s language choices, what do you do if you want both? There’s still only one option: use Smalltalk.

You be the judge.

Module Mania: A Type-Safe, Separately Compiled, Extensible Interpreter

To illustrate the utility of a powerful modules language, this paper presents the embedded interpreter Lua-ML. The interpreter combines extensibility and separate compilation without compromising type safety. Its types are extended by applying a sum constructor to built-in types and to extensions, then tying a recursive knot using a two-level type; the sum constructor is written using an ML functor. The initial basis is extended by composing initialization functions from individual extensions, also using ML functors.

This is an excellent example of how the ML module language doesn't merely provide encapsulation but also strictly adds expressive power. It also demonstrates how a dynamic language (Lua) can be embedded in the statically-typed context of ML. Finally, it demonstrates that none of this need come at the expense of separate compilation or extensibility. Norman Ramsey's work is always highly recommended.

Classic Java

This collection is an implementation of (most of) ClassicJava, as defined
in "A Programmer's Reduction Semantics for Classes and Mixins," by Matthew
Flatt, Shriram Krishnamurthi, and Matthias Felleisen; in _Formal Syntax and
Semantics of Java_, Springer-Verlag LNCS 1523, pp. 241-269, 1999. A
tech-report version of the paper is also available at
<http://www.ccs.neu.edu/scheme/pubs/#tr97-293. The implementation is
written in PLT Redex, also available through PLaneT. Please consult that
package's documentation for further details.

This might be interesting to folks curious about how to formalize a real language, or about how PLT Redex works in practice.

A couple of small items that caught my attention.

• Fritz Kunze (President of Franz Inc.) reveals the secrets to successful programming language business.
• An interview about reddit which includes the ultimate question: Why Lisp?
• Tim Bray on abstracting the Web using continuations (well, sort of).

LtU readers know that I am long time advocate of code reading. As I've argued here in the past, reading great code is the best way to acquire good programming skills. It's also a pleasure to read good code. Yes - reading code can be fun.

It turns out that I am not alone (though my conception of a code reading workshop is perhaps somewhat different than the things discussed there).

Anyway, this is a chance to continue one of my pet memes. Many of the pieces of great code I've read over the years come from language processing tools (e.g., compilers, meta-programming systems etc.) I don't think this is a coincidence.

Now's your chance to tell us your favorite examples.

The rules: The code must be beautiful and it must be programming language related (and no, being written in a programming language isn't enough).

The most recent version of Objective Caml is 3.09.0. It was released on 2005-10-27.

Some of the highlights in release 3.09 are:

• Introduction of private row types, for abstracting the row variable in object and variant types.
• Added warnings Y and Z for local variables that are bound but never used.
• More portable implementation of the -pack option to ocamlopt.

For more information, please consult the comprehensive list of changes.

From this Wired article:

In 1976, computer pioneer Edsger W. Dijstra made an observation that would prove uncanny: "Program testing can be quite effective for showing the presence of bugs," he wrote in an essay, "but is hopelessly inadequate for showing their absence."

Thirty tears later, Dijsta's words have the ring of prophecy. Companies like Microsoft and Oracle, along with open-source projects like Mozilla and Linux, have all instituted rigorous and extensive testing programs, but bugs just keep slipping through. Last month, Microsoft's monthly drop of bug patches included fixes for 14 security holes that escaped prerelease testing, four of them rated "critical."

There's a bit to chew on here, including the by-now-de rigeur misidentification of Java, Python, and Perl as "type-safe languages." But I think the article is valuable in spite of that for its frank admission that even intense testing regimes aren't doing well at addressing serious quality issues. Daniel Jackson, leader of the Alloy project at MIT, is quoted.

Microsoft's PDC videos are online, including some that are of interest to us.

Paul Vick directs us to three presentations: (1) the future of VB; (2) Dynamic languages on the CLR; (3) LINQ.

Note: You need to use IE to view these presentations.

(via Keith)

Io is small, pure object oriented, prototype-based programming language. The ideas in Io are mostly inspired by Smalltalk (all values are objects), Self, NewtonScript and Act1 (prototype-based differential inheritance, actors and futures for concurrency), LISP (code is a runtime inspectable/modifiable tree) and Lua (small, embeddable).

The paper and slides are available here.