If you use 0!:100 rather than ". you can do it more easily:
0!:100 'copyoflist=.', 5!:5<'list_z_'
copyoflist
3 : 0
w=.{.wcsize''
...
)
0!:100 is multi-line ". with only side-effects, no return value.
Henry Rich
On 2/18/2012 3:10 PM, Raul Miller wrote:
> In another thread, I was struggling to discuss issues which conflicted
> with the topic.
>
> So... I am making a new topic: Given a nameable entity, in J,
> construct a list of characters that can be used in ". to recreate that
> nameable entity. (A nameable entity, in J, is something that can be
> enclosed in parenthesis and still be syntactically valid.)
>
> This mechanism is very like the "serialization" that I use in other
> languages, so I will call it "serialization".
>
> Serialization is very like J's linear representation, but not quite.
> The problem with linear representation, is that it's not always valid
> for ".
>
> Here's an example of the reason we cannot use linear representation
> (5!:5) for serialization:
>
> ".'copyoflist=.',5!:5<'list_z_'
> |spelling error
>
> Or, more formally:
> ".'copyoflist=.(',(5!:5<'list_z_'),')'
> |spelling error
>
> 5!:5 does not always generate a character sequence which is valid
> between parenthesis, when it is presented with a name which is not a
> noun. Apparently, though, when given a noun, it always serializes the
> noun. [I do not have handy any written guarantees of this, but I also
> have not been able to construct any counter examples.)
>
> So, that suggests a serialization mechanism like this:
>
> serializeNamedEntity=: 3 :0
> select. nc<y
> case.0 do. 5!:5<y
> case. do. '(',')`:6',~5!:5<'m' [ m=. 5!:1<y
> end.
> )
>
> And, as a test:
>
> ".'example1=:',serializeNamedEntity 'serializeNamedEntity'
>
> 'example1' (-:&(5!:1)&<) 'serializeNamedEntity'
> 1
> ". ']&example3=:',serializeNamedEntity 'example2'[ example2=: a.
>
> 'example3' (-:&(5!:1)&<) 'example2'
> 1
>
> It's probably also good for adverbs and conjunctions (which is why I
> had the entity specified by name, rather than by value).
>
> This depends on undocumented behavior of 5!:5 and of `:6, but it seems
> reasonably robust.
>
> It might be worthwhile using 5!:5 directly, and testing its result and
> falling back to the longer mechanism only when necessary.
>
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