When introducing J, we often point to +/ # % as a sterling example of J's stark clarity. In fact, we've done it so much, it's become something of a cliche; though true, it begins to ring hollow.
So let's introduce some variety. What other phrases could we substitute as exemplars? Perusing http://www.jsoftware.com/jwiki/Essays/Polyminoes this morning, I am reminded of the phrase for all permutations: A.&i.~ ! NB. For input N, produces all permutations of order N (in lex. order) This monad is a good candidate for several reasons, particularly those which render it lean and spare with nothing superfluous (a characteristic it shares with +/%#, and which greatly contributes to the latter's fame). - succinctly describes a well-known concept (permutations, AKA anagrams). - leverages J's unique train syntax. - whereas +/%# is a good example of a fork, A.&i.~! is a good example of a hook. - doesn't mention its arguments (even by reference with []), and so a great specimen of tacit expression. - &i. is a sophisticated use of duality (one of J's more unique composition operations). - mnemonic (A. recalls Anagrams, ! recalls permutations [factorials and permutations are closely related]) - aesthetically balanced (the inflections on A and i reflect each other, as the ! reflects the i) What other Jems are suitable to introduce the language? Why do you think so? -Dan ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
