Ralf Hinze. An algebra of scans. Proceedings of the Seventh International Conference on Mathematics of Program Construction (MPC 2004).
In this paper we show that parallel prefix circuits enjoy a very pleasant algebra. Using only two basic building blocks and four combinators all standard designs can be described succinctly and rigorously. The rules of the algebra allow us to prove the circuits correct and to derive circuit designs in a systematic manner.
Parallel prefix computations, or scans if you speak APL, determine the sums of all prefixes of a given sequence. Obviously the term sum is used loosely: scan is a high-order function, and any associative operation can be used. In J talk scan is an adverb.
I wonder when we will be seeing courses called Algebra Design in Computer Science departments around the world...
Ah right, just after all universities offer language design courses ;-)
Durham students have fun again ;-)
Peter linked to the MOZ 2004 papers earlier.
This presentation by Raphael Collet provides a nice example of constraint programming, a paradigm we don't discuss often enough.
A thread over on the PLT mailing list that LtU-ers may find interesting.
The thread isn't very technical, and the title may be a bit misleading: It's more about programming skills than about programming by non-programmers.
I wonder how many people outside the PL community would agree with the statement that Programming is just another name for the lost art of thinking. Perhaps a better formulation would be Programming, done right, is just another name for the art of thinking.
And by done right I mean using the right languages, of course.
The MOZ 2004 "Second International Conference on
From Microsoft Research:
More from Slashdot, which today points to an article on Rel, Dave Voorhis' open source implementation of Tutorial D (see Chris Date and Hugh Darwen's The Third Manifesto for a discussion of the rationale behind this language).
Discussions of possible replacements of, or improvements on, SQL usually end up being all about the powerful institutional/human factors (or "network effects") that will impede acceptance of any new solution. Refreshingly, Voorhis is going ahead and building one anyway, without waiting for approval from the masses. It might catch on, or it might not; at least someone's giving it a go.
Three part series on R that's of interest for domain specific PL development. First parts can be found at Part 1: Dabbling with a wealth of statistical facilities and
A three-part series, ...introduces you to R, a rich statistical environment, released as free software. It includes a programming language, an interactive shell, and extensive graphing capability. What's more, R comes with a spectacular collection of functions for mathematical and statistical manipulations -- with still more capabilities available in optional packages... The (GPL'd) R programming language has two parents, the proprietary S/S-PLUS programming language, from which it gets most of its syntax, and the Scheme programming language, from which it gets many (more subtle) semantic aspects.R and S were touched on fairly briefly in the LtU discussion about Regression Analysis. A more detailed introduction can found be found at An Introduction to R.
It's different enought that I don't really know what to make of it - is this the future? Or a testbed for ideas that will find more durable expression in another context?
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