On 7/5/07, david alis <[EMAIL PROTECTED]> wrote:
Raul's method of reducing the replacement problem into simple arithmetic is a classic.rpl2=: ] - (0 ,~ -/)@[ {~ ] i.~ [EMAIL PROTECTED] It'd be nice to know when he first used it
First, I should note that (if you're going for conciseness) that expression contains a token which can be eliminated with a fairly obvious rephrasing. Second, I used analogous mechanisms in APL back in the '90s (but my memory is not good enough for me to say much more than that). Third, I have frequently wished for an operation analogous to addition (1-to-1, with an identity element and an inverse operation) which worked across the full domain of J's verbs. But I have never been able to comfortably decide what other properties it should have for literals and boxes. But, even without an inverse and support for nothing beyond the identity operation, this could be useful (for example, assembling data in a list using two different mechanisms, using "zeros" (fills, presumably) as placeholders for elements coming from the other mechanism -- this hypothetical operation could then combine the two results. -- Raul ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
