[Jprogramming] Definition: Frame of an argument

[Henry Rich]

It sounds like your original confusion was between empty arguments 
(where the frame contains 0) and an empty frame (which simply means that 
the verb operates on a single cell).

http://code.jsoftware.com/wiki/Vocabulary/EmptyArguments

has more on this topic.

Whenever an earnest user has confusion with the documentation, I want to 
improve the documentation.  Can you think where a timely word would have 
helped?

Henry Rich

On 1/15/2016 2:43 AM, Matthew Baulch wrote:
> Thanks Roger. That's perfect. I see what you mean: frames with 0 sometimes
> make sense, and zero frames prevent unnecessary awkwardness and ambiguity
> in these cases. Very good examples!
>
> On Fri, Jan 15, 2016 at 5:57 PM, Roger Hui <rogerhui.canada at gmail.com>
> wrote:
>
>> Empty frame, or more accurately zero frames, if it is said to be for
>> anything, is to allow edge cases, the case where the frame contains a 0, to
>> work without a lot of exceptions, without the programmer having to write
>> extra code.  An example hopefully illustrates this point.
>>
>>     x ,"1 y=: i.3 4
>> 10 20 30 0 1  2  3
>> 10 20 30 4 5  6  7
>> 10 20 30 8 9 10 11
>>
>> In this case the left frame is '' and the right frame is }:$y, (,3) in this
>> case.
>>
>>     x ,"1 y=: i.2 4
>> 10 20 30 0 1 2 3
>> 10 20 30 4 5 6 7
>>     x ,"1 y=: i.1 4
>> 10 20 30 0 1 2 3
>>     x ,"1 y=: i.0 4
>>
>> The right frames in the successive examples are (,2), (,1), and (,0).  The
>> last is an example of a zero frame, and the example worked with no fuss.
>> The following sequence makes more salient the consistent treatment of
>> frames, including zero frames.
>>
>>     $ x,"1 y=: i.3 4
>> 3 7
>>     $ x,"1 y=: i.2 4
>> 2 7
>>     $ x,"1 y=: i.1 4
>> 1 7
>>     $ x,"1 y=: i.0 4
>> 0 7
>>
>> The reason why zero frames requires extra discussion is because ordinarily
>> you have argument cell(s) for the verb to apply to, and the result cells
>> and hence the result is not in question.  With zero frames, there are no
>> argument cells, so the system needs to do something extra (so that you
>> don't have to).  (x,"1 y appends vectors to vectors, but when y is i.0 4 it
>> does not have any vectors.)
>>
>>
>>
>> On Thu, Jan 14, 2016 at 10:35 PM, Matthew Baulch <baulch.matt at gmail.com>
>> wrote:
>>
>>> And the dictionary defines frame.... such that it may be empty? I'm most
>>> interested in whether, supposing this is the case, allowing empty frames
>>> serve (an)other purpose(s) in the structure of the language.
>>>
>>> Apologies if my original phrasing was unclear.
>>>
>>> Every decision in the design of J seems very deliberate—which I really
>>> appreciate. It just seems that empty frames must serve a purpose. Trying
>> to
>>> work it out.
>>> On 15 Jan 2016 4:21 pm, "bill lam" <bbill.lam at gmail.com> wrote:
>>>
>>>> The J dictionary is always correct.
>>>>
>>>> Пт, 15 янв 2016, Matthew Baulch написал(а):
>>>>> Fair enough, though I can't work out whether the dictionary agrees
>> with
>>>>> NuVoc here or not. Either way, which definition of frame is correct?
>>>>> On 15 Jan 2016 3:48 pm, "bill lam" <bbill.lam at gmail.com> wrote:
>>>>>
>>>>>> For J implemention, the only authority is the J dictionary since
>>>>>> it defines the J language.  You need not worry anything else.
>>>>>>
>>>>>> http://www.jsoftware.com/help/dictionary/dictb.htm
>>>>>>
>>>>>> Пт, 15 янв 2016, Matthew Baulch написал(а):
>>>>>>> I assume the intended definition of 'frame', in relation to verb
>>>>>> arguments,
>>>>>>> is that given on
>>>>>>>
>>>>>>> http://code.jsoftware.com/wiki/Vocabulary/FramingFill
>>>>>>>
>>>>>>> I'm just trying to understand verb/argument combinations with
>> empty
>>>>>>> frame--the most common case, I suppose.
>>>>>>>
>>>>>>>  From the wording "each argument is ... an array of [r-cells]. The
>>>> frame
>>>>>> ...
>>>>>>> is the shape of this array of [r-cells]", it seems that a frame
>>>> should
>>>>>>> never be empty, but in fact have a minimum shape of '1'. Of
>> course,
>>>> this
>>>>>>> ties into the wording of many other statements. In the case of
>>> dyadic
>>>>>>> verbs, for instance,
>>>>>>>
>>>>>>> "frames must agree ... they must be identical or one must be a
>>>> prefix of
>>>>>>> the other" (stated in link above)
>>>>>>>
>>>>>>> as opposed to
>>>>>>>
>>>>>>> "frames must agree ... one must have shape 1 or be a prefix of
>> the
>>>> other"
>>>>>>> (the way I see it, assuming equality implies prefix-of)
>>>>>>>
>>>>>>> Can anyone shed some light on this? Is there an important reason
>>> for
>>>> this
>>>>>>> convention that I'm missing, or is it of little consequence?
>>>>>>>
>>>>>>> I'm implementing (or trying to...) a subset of J for the JVM, and
>>>> this is
>>>>>>> one little detail that's bothering me.
>>>>>>>
>>>>>>> Thanks.
>>>>>>>
>>>>>>> Matt Baulch
>>>>>>>
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