Lambda the Ultimate

While reading papers on (behavioral) reflection, I keep pondering - how are they going to establish and maintain security in famous "reflective towers"? I have difficulties to understand, whether trying to do capabilities security in reflective setting is not going to result in infinite regress.

One would probably want to provide reflection via capabilities, which themselves may be a subject of reflective interest, etc.

I am not sure capabilities are any different from standard "turtles all the way down" issues of reflection (and meta-programming), though. I would like to come up with some formal model to play with it, but didn't succeed yet (probably I need to think a bit longer :) ). Does anybody have some pointers/ideas on how capabilities and reflection interwingle?

Courtesy of Slashdot, and not really about languages per se, just an interesting project that happens to have been written in OCaml, dbfs.

The Human-Language Interface

PowerPoint slides from Matthias Felleisen's presentations page. He discusses the HtDP educational philosophy and PLT research experience.

Some of the figures are undecipherable, but there's lots of interesting stuff in there. The pedagogical approach to the human factors issues of programming languages has turned out to be really productive.

(P.S. - Is there anything un-politic about posting references to your own professor's work?)

"An age old question asked of language design is whether or not library design is language design. Because interfaces are themselves little languages, and libraries implement interfaces, library design must be a form of linguistic extension, even if an extremely rudimentary one. In practice, library design is difficult, and the hard problems that library designers encounter - how to balance hiding and exposing functionality, how to preserve invariants, what types to create, export and make opaque, what static and dynamic scope operators to provide, and so forth - are really linguistic ones. So it is heartening to note that the design of unit/lang not only encompasses this form of language extension, but blurs the distinction between these two forms in a way traditional language extension mechanisms (such as macro systems, extensible grammars or operator overloading) do not."
p67 "Linguistic Reuse" DPhil thesis 2001 pdf Shriram Krishnamurthi

Over on Slashdot I saw a thing about a guy hacking Perl in a live musical performance, and it got me wondering again if music and programming can be fused even more tightly, so that code itself is musical?

Being something of a geek for obfuscated languages, I wrote one of my own called SC5, which is based upon the simon-says dance commands from the video game "Space Channel 5". The idea is that the same program text can be executed as an algorithm or performed as a rhythmic piece (as in the game). Unfortunately I haven't yet written an interpreter that will perform SC5 code musically but theoretically, anyway, it's possible.

Anyone else interested in this sort of thing?

Without wishing to cause a flame war, ..., well actually I do wish to start a discussion ...:)

For the last 25 years I have been working on programming languages roughly in the logic programming/functional programming paradigms.

About 10 years ago I embarked on a research trajectory involving moving from Prolog's 'meta-order' approach to a higher-order approach.

The reasons were technical: meta-order sucks from a software engineering POV.

However, recently, I have changed my mind. Or rather, changed direction.

While robust, HO does not deal with OO programming all that well. (Start flame wars here)

The reason is that OO involves combinations that are difficult for HO styles of programming.

On the other hand, OO does nearly everything that HO can do. I would argue, that at a slight loss of elegance, OO does *everything* that a good software engineer wants to do.

My reasoning is based on the fact that an object can act as a kind of closure but a closure cannot capture the multiple uses of an object - together with the interface contract.

BTW, as far as I am concerned, OO is *not* equivalent to inheritance+subtypes+methods+classes+instances. Those are techniques useful in some situations.

For me, OO is fundamentally about encapsulation and interfaces. The rest is noise (in my opinion of course)

So, in my most recent work, I am throwing out my HO implementations and replacing them with an Object Order implementation....

Comments?

From Mike Davidson's blog: a web designer gets an education in floating-point arithmetic.

Something happened today which shook the very foundations of what I’ve always believed about computers. See, maybe this was just a crazy notion, but I was always under the impression that if there was ONE thing computers did well, it was math. Simple math, algebra, geometry, calculus… it didn’t matter. Computers have always been equation solving machines. Or so I thought. — Apple Flunks First Grade Math

Not really about programming languages, but I thought it was interesting to see a non-programmer's reaction to a basic programming issue. I say "non-programmer", and yet Davidson is apparently knowledgeable enough to write Flash code and Javascript DOM applications.

As programming skills become more and more necessary in non-programing fields, I expect we will see more and more people writing code with less and less understanding of what they are doing, and a piecemeal education will become (even more) the norm. How can/should we, as programming professionals and researchers, deal with that?

Sometimes new languages are used in the design of jewels, and authors may attribute a product's success to the use of a particular language or type of language. Here, I have grave doubts. I have lost count of the number of languages that have been introduced to me as the solution to the software problems that everyone experiences.

"Why Software Jewels Are Rare" pdf David Lorge Parnas

(Apparently a response to "A Plea for Lean Software" pdf Niklaus Wirth)

a while back, in the last days of userland, there was some discussion about putting advertising on this site to help pay for hosting, upkeep, etc.

i don't know where or how the site is hosted now, but even if it's in a forgotten corner of some kind company or institution's server, it seems to me that there would be no harm if the people involved in maintaining this site (not me, in case you're suspicious ;o) made a tiny profit. especially if it adds something to the site.

anyway, i'm mentioning this now not because i have a sudden desire to see google textads on every page, but because i've been looking at the amazon associates program. they pay a commission for any purchase made via certain links (so you provide a link saying "buy this book from amazon" that people click on). i was kind-of hoping i could become an associate, recommend books to myself, and then buy them at a discount. strangely enough, that seems to be against the conditions. so i then thought "well, who would i want that commission to go to, if i can't have it...?"

if this seems at all sensible, go to amazon, click on the "help" link and then type "associates" in the search box.

seems to me you could start with a page of classics, add a forum where people recommend new titles, and take it from there...

Someone on comp.lang.python remarked

It is just funny how easy horizontal slicing is made (list[:]) but how "difficult" vertical slicing is. It is a common task and one does not realize how often one does need vertical slicing. eg.: getting the keys of dictionary is a vertical slicing, or turning a list into a dict involves vertical slicing...

Just out of pure curiosity: Is there a langue that allows vertical and horizontal slicing and dicing with the same built-in pattern?

The basic problem is, of course, that multidimensional arrays are implemented as arrays of arrays, but that made me wonder in turn - which languages have true multidimensional arrays? (i.e., arrays in which every dimension is treated as equivalent)