The issue:
ipm =: 3 : 0
ip =: 2 (0}) ip
)
ip =: i. 3
(ipm '') ] ip
2 1 2
As you see, ip was modified by call to ipm, which did an in-place
assignment. This violates the rules, which say that the value of ip
should have been stacked. In fact, a pointer to the value is stacked.
This requires a decision. I think we need a committee of J Language
Experts to decide how to resolve issues like this, and future enhancements.
The choices as I see them are:
1 - Fix to conform to the Dictionary. Possible; would slow things down
a little; would make some assignments currently done in-place perform a
copy.
2 - Ignore it. Leave as is.
3 - Embrace it - declare that in-place assignments to global variables
may affect previously-stacked references to the same name. [With local
variables the problem does not arise]
Now we need a Language Committee, and a decision.
Henry
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