As I contemplate the structure of the Fold operations, I note that appplying the v-verb after the u-verb is alphabetically sensible, but contrary to the application order of u@v, and to the right-to-left flow of attention and data in J-expression evaluation.
I recommend an early revision of the Fold definition, interchanging the meanings (not the positions) of u and v (left and right operands), and thus their locations in the descriptive diagram. It would also help psychologically to flip the diagram side-to-side. ------ On Sat, 28 Mar 2020 19:19:07 -0400 Henry Rich wrote: You can do whatever you need without Fold, but it has these features: * iteration can be forward or backward through items of a noun * initial value can be provided as its own argument * early termination is allowed * either one result for the whole iteration or a result item per iteration ** result of an iteration can be a subset of the complete internal state passed to the next iteration ** results of individual iterations can be put into the overall result or not * iteration can be by item or on the entire argument until a condition is met Henry Rich ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
