Shakespeare would have enjoyed this listbox topic (Much Ado About Nothing :-) … 
(joke)

> On 7 Jun 2017, at 12:33 pm, robert therriault <[email protected]> wrote:
> 
> To further illustrate  Raul's post using Shape ($)
> 
>    my_empty =: }. 1
>   my_empty        NB. Empty list
> 
>   $ my_empty      NB. Shape of empty list
> 0
>   f my_empty      NB. 1 prepended to empty list
> 1
>   $ f my_empty    NB. Shape is now 1 --  $ 1,my_empty
> 1
>   < my_empty      NB. my_empty is boxed
> ┌┐
> ││
> └┘
>   $ < my_empty    NB. Box is an atom -- shape is empty
> 
>   $ each < my_empty NB. Inside box is shape 0 -- each=:&.> is an adverb that 
> opens the box, then performs the action on contents, and closes the box
> ┌─┐
> │0│
> └─┘
> 
> I would add to Raul's observation about which problems 'fit' J; it is usually 
> my 'way of thinking' about the problem that does not 'fit' J. If you state 
> the problem then you may find that the solution is found by changing the 
> structure of the data or some other paradigm shift. I am always amazed at the 
> creativity of the people on this list when it comes to problem solving.
> 
> Cheers, bob
> 
>> On Jun 7, 2017, at 10:11 AM, Raul Miller <[email protected]> wrote:
>> 
>> What you are seeing here is not an empty list of boxes but a box
>> containing an empty. Or, ok, yes: "an empty box".
> 
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