We have talked it over & we agree with this change. The 'v before u'
has mnemonic value as you say. In addition it puts the programmer in a
right-to-left frame of mind, which might make it easier to remember that
the computation moves right to left, like u/, with the result of one
cell feeding into the right argument of the next cell.
This is an incompatible change. It will come in with the first 9.02
beta. Hear that, Ruda?
The other change that has been suggested to Fold is to reverse the use
of u/v to have the new cells come in on the right rather than the left.
We are not going to make that change.
Henry Rich
On 4/3/2020 12:06 AM, Arthur Anger wrote:
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.
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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
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