> Backus had a reciprocal relationship with APL. > He admired it but didn't think it had gone far > enough. In his FP he described an "insert" > function which was later adopted by APL, as a > better way to describe what was then called > "reduction" in APL.
I don't think this description of how "insert" got into APL is accurate. APL had slash and slash-bar many years prior to Backus' August 1978 paper. Iverson in his "Operators and Function" (1978-04-26) described a innerproduct/ example, and innerproduct slashbar was interpreted exactly the same as how innerproduct/ is interpreted in J today. It _is_ better to call / "insert" rather than "reduction" because for an arbitrary function f, f/ may not reduce anything. In older APLs f/ was restricted to scalar functions, and in such cases f/ does reduce an axis. Backus discussed APL in section 8 of his 1978 paper. He erroneously described APL as having "exactly three functional forms, called inner product, outer product, and reduction". As of 1978, there were two others: bracket axis (APL\360 circa 1966) and scan (APLSV circa 1972). ----- Original Message ----- From: Eugene McDonnell <[EMAIL PROTECTED]> Date: Monday, March 19, 2007 8:13 pm Subject: Re: [Jgeneral] John Backus Died > > On Mar 19, 2007, at 7:53 PM, June Kim wrote: > > > http://www.nytimes.com/2007/03/19/obituaries/20cnd-backus.html? > > _r=1&oref=slogin > > ----------------------------------------------------------------- > ----- > > For information about J forums see > http://www.jsoftware.com/forums.htm > Backus had a reciprocal relationship with APL. He admired it but > didn't think it had gone far enough. In his FP he described an > "insert" function which was later adopted by APL, as a better way > to > describe what was then called "reduction" in APL. > > It was some of his cohorts who,without meaning it, benefitted APL; > > they were in charge of a computer, but chose not to give all 8 > bits > of a byte. Since this was required by the APL group, they had to > go > their own way, successfully. > > My first manager at IBM was Andy Kinslow, who was another one of > the > group that included Backus. With Andy, I helped create the first > IBM > time-sharing system. > > Eugene ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
