En attendant les notes de cours et l’énoncé du TP, voici un article que j’avais écrit juste après avoir découvert Factor.
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John Haugeland said:
“Uh, no, it isn’t. J and APL share the same damning problem: they see the world as arrays, so when it comes time to do anything that isn’t array bound, you get ground to a halt. That’s why they’re both dead languages.”

John,

I routinely perform queries and calculations on huge amounts of data using J. The performance of J has changed the game for me.
No longer do I build large databases with queries that take minutes or hours to run, now I can load the same data in J’s data engine (JDB) and run the same queries in sub-second times. In addition, I have the freedom to do manipulate the query results in ways that would be very difficult in other languages. I’m not saying that J is easy to learn, but the time you spend with J is time well spent.

Pour une bonne raison d’utiliser les monads, vous pouvez lire cet article où j’expliquais comment le fait d’avoir choisi un type monadique plutôt qu’un simple Maybe augmente automatiquement les possibilités du programme. Nous…

Have you seen Richard Bird’s approach to sudoku? He gave it as a Functional Pearl talk at the Portland ICFP (2006, I think); it was also written up as a JFP pearl, apparently in Volume 16, #6.

Hmm, sudoku is naturally array-oriented … there must be a good J solution that fits in one line! (Sorry, I just came here from your “J programming language” blog entry and couldn’t resist.) Nested arrrays, á là APL 2, would be better, if J has them.

“J isn’t even particularly efficient in the few data structures it knows how to do.”

“… J and APL aren’t particularly expressive. Whereas yes, their syntax and notation are surprisingly dense, and well suited to trivial math toys, …”

Regarding efficiency, IBM’s APL compiler from the mid 1980’s actually beat their optimizing “H” FORTRAN compiler on boolean array manipulation (presumably because it could “see” the forest of an algorithm expressed in APL better than the “trees” expressed in FORTRAN-style nested loops). So I would be cautious before assuming that J can’t be implemented efficiently.

Regarding paucity of data structures, APL 2 at least has nested arrays, which can make up for some of the blinders (I don’t honestly know if J has them or not). One could just as easily toss tomatoes at LISP and Scheme for “only” having S-expressions, or at Haskell for “only” having algebraic data types (although neither of these is quite true). I have actually heard exactly this done over the years in various venues. Of course for real-world problem solving, one would like to have the widest variety of concepts that can fit comfortably in one’s paradigm, but there is great value in exploring ways of expressing things with a “restricted” set of concepts and language. (E.g., pure functional style, or logic programming, constraint-based, etc.)

But I find your “trivial math toys” remark especially ironic: many, many people would level the same criticism against Haskell (and Clean and Erlang and others you mention as well). Many, many people did, especially a couple of years ago, before STM, RWH, etc.

Can’t we just leave it at “J is interesting, fun, and will change your perspective on what’s possible”? As will Haskell, Clojure, Scheme, Erlang, etc., albeit in different ways.

Why rain on someone’s parade as they experience the joy of a new language? Why not be more charitable? (Hey, Sam, Joy and Charity are another fun couple of languages: check ‘em out!)

I guess I just find the “X isn’t a REAL programming language” kind of talk counter-productive and a little tiresome, independent of the X involved. I’ve heard it said about APL, LISP, C, SML, Scheme, Haskell, Java, Miranda and lots of others over the years, and I’ve enjoyed using all those languages in their own way.

Can’t we leave this kind of “trash talk” to the high school football crowd, or their “grown-up” counterparts, the war and religion crowds? Do we really have to constantly hear this kind of stuff from the programming language geek crowd?

(Yeah, I know: me and Rodney King, both. I’ll get off my own soapbox now . And nothing personal, John, everyone seems to do it … .)

the speed is good. It is a fully dynamic language so good is relative to other dynamic languages.

IMO, data structures is a huge strength of J. Weaknesses, IMO, are the maintainers refusal to add enhancements useful for DSLs, and a lack of batteries.