but J .. beautiful as it is, isn't just for looking at .. it's for constructing. Design may be top down, but our thoughts in terms of construction form an expression beginning with the detail and develop towards the final outocome - and our characters appear on the page from L->R.
So, taking the example from http://www.jsoftware.com/papers/EvalOrder.htm to determine the divisiblity of a number(n) by 9 ... (d : n's digits) L->R flows naturally from the keyboard d/+|9=0 .. unlike L<-R ( 0=9|+/d ) , there's no having to keep in mind an imagined expression which is being operated on on the right while construction is taking place. for L<-R there's conflict between natural direction of construction and the direction of the expression on the line. On 2011-08-14 06:56, Raul Miller wrote: > On Sat, Aug 13, 2011 at 11:05 PM, mijj<[email protected]> wrote: >> .. plus .. while on the subject of direction .. why was APL thus J >> direction of evaluation set to be right to left? .. wouldn't it'd be >> more natural as left to right? (ie. the same direction as writing, or >> the direction which represents the progression of time) > > If you look at J top down, it is left to right. > > If you look at J bottom up, it is right to left. > > V=: 1 + 1 > > If J reversed its evaluation order, how would that work? > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
