That also would mean that Paul's solution could be simplified as assignment of
m is not required, just the mention of it.
now=: 1 : 0
y[m
)
1 now 'cat'
cat
Great explanation Henry
Cheers, bob
> On Aug 7, 2020, at 09:10, Henry Rich <[email protected]> wrote:
>
> Is it a bug? More a continuing penance for an initial faulty design.
>
> https://code.jsoftware.com/wiki/Vocabulary/com#Details note 11 describes the
> situation.
>
> In early J, the names u/v/m/n had not been invented, and an explicit modifier
> had only the names x and y to work with. x was what we now call u, and y v.
> Obviously, such a modifier was very restricted: to produce a modifier as we
> now know it, with access to u/v/x/y, the modifier would have to create the
> text after substituting its x/y, and have that reinterpreted by (3 : n) to
> create a verb. That definition didn't last long, but while it was in force a
> few simple system modifiers were written, for example
>
> bind
> 2 : 'x@(y"_)'
>
> Nowadays we would write 'u@m' or 'u@(m"_)'. The language wasn't even weaned
> and it had a compatibility problem!
>
> The 'solution', still in place today, was to inspect the text of the
> modifier. If no reference to u/v/m/n is found, the modifier is assumed to be
> old-style, and the names x and maybe y are defined as the modifier arguments.
> With your example, an adverb has no y, so y is left undefined and you get a
> value error. This error is detected when (1 now) is executed. You want a
> new-style modifier that defers execution until the (modifier+u/v) sees 'cat'.
>
> To get a new-style modifier, you have to have u/v/m/n in there somewhere.
> Just as you discovered.
>
> Henry Rich
>
>
> On 8/7/2020 11:28 AM, Paul Jackson wrote:
>> This is not where I began. I had lots of use of the m argument, but all of
>> it in quotes. It took me a while to isolate the problem to something this
>> simple. Now that I have, I have also found other errors are signaled with
>> the dyadic case of an adverb, and both cases of a conjunction. As my second
>> example shows, I can avoid the problem with an unnecessary use of the name.
>> I can provide details if anyone has trouble replicating the rest of the
>> issues. What I'm hoping for is a confirmation that this is a bug.
>>
>> Paul
>>
>> now=: 1 : 0
>> y
>> )
>> 1 now'cat'
>> |value error: now
>> | y
>>
>> now=: 1 : 0
>> y [m=. m
>> )
>> 1 now'cat'
>> cat
>>
>> JVERSION
>> Engine: j901/j64/android
>> Release-f: commercial/2020-06-12T10:01:40
>> Library: 9.01.24
>> J Android: 1.4.09/9/28
>> Platform: Android 64 (arm64-v8a)
>> Installer: unknown
>> InstallPath: /storage/emulated/0/Android/data/com.jsoftware.j.android/files
>> Contact: www.jsoftware.com
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>
>
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