trace can be confusing. It runs in its own locale, and names that you
think are defined are not defined to trace. In this case, a is not
defined to trace, and trace thinks it is a verb.
Define a in z locale, and trace will do what you expect.
load 'trace'
erase <'a'
1
a_z_ =: /
trace 'a /'
--------------- 6 Bident -----
/
/
//
==============================
trace 'a a'
--------------- 6 Bident -----
/
/
//
==============================
Henry Rich
Viktor Cerovski wrote:
>
> Brian Schott wrote:
>> The console session below is meant to suggest a way that execution can
>> be observed. Also, notice that one of the examples is an Adverb
>> execution and the other is a Bident.
>>
>> load'trace'
>> erase <'a'
>> 1
>> a =. /
>> trace 'a /'
>> --------------- 3 Adverb -----
>> a
>> /
>> a/
>> ==============================
>>
>> trace 'a a'
>> --------------- 6 Bident -----
>> a
>> a
>> a a
>> ==============================
>>
> Brian, I know both of these rules. My claim is that the evaluation rules of
> J can
> be formulated in such a way that both (a /) as well as (a a) are evaluated
> using the Bident rule without any effect on the results of an arbitrary J
> program,
> and because of that the above demonstration is irrelevant.
>
> In particular, it doesn't explain why in the previous examples
> (v a) evaluated to v/ while (a a) evaluated to itself rather than //
>
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