This whole idea of verbs returning any part of speech seems like a
disaster. Perhaps after reflection it will be workable, but I would
start by assuming that Ken and Roger weren't just thoughtless in
restricting the range of verbs.
It is pretty basic that every name must have a part of speech; otherwise
how can you parse? And if verbs are unrestricted, if I see
q =: V1 V2 V3
what part of speech can I assign to q?
I think it's a bug and should be fixed.
I do wish I had the old tacit language back, though.
Henry Rich
On 1/26/2013 5:03 PM, Marshall Lochbaum wrote:
First, let me say: wow. Using a (or the more general dont from Dan's
post, which I will use and call d), we can PUT ANY J OBJECT IN A BOX.
This means it can be passed around as a noun and invoked in an explicit
context.
d =. (]^:(1:`(<'@.')) nest2Box)@:gTxt
]infix =: <@d '/'
┌─┐
│/│
└─┘
+ (>infix) 3 4 5
12
As long as we are inside the same tacit verb where d was called, its
output will be treated as a noun, despite the fact that it isn't:
d@> '@&'
@
([: $ d@>) '@&'
2
([: |. d@>) '@&'
&
([: (<"0) 3 3 $ d@>) '@&'
┌─┬─┬─┐
│@│&│@│
├─┼─┼─┤
│&│@│&│
├─┼─┼─┤
│@│&│@│
└─┴─┴─┘
Note that this clearly shows that the output of d@> '@$' is still a
list, even though it's displayed and treated as a single conjunction.
Once we exit the verb into an explicit context, the parser figures out
that it is dealing with a non-noun and starts treating it like one.
use =: 3 : 'y 2 3 4'
use@:d '+/'
9
I don't think it's possible to use the result of d in a tacit context,
but I could be wrong. Of course explicit helper verbs that take boxed
things and apply them to other boxed things could be used, and they
could even be made polymorphic using 3!:0 .
This is, of course, a bug. I can't find anywhere in the dictionary where
it says a verb must return a noun, but it's assumed throughout, and
explicit verbs are specifically made to throw a domain error rather than
return something that's not a noun. However, it's really cool and quite
possible useful--passing arbitrary J objects through verbs without the
overhead of gerunds or the hassle of names is very cool.
Marshall
On Sat, Jan 26, 2013 at 07:58:49AM -0500, Raul Miller wrote:
On Sat, Jan 26, 2013 at 1:38 AM, Jose Mario Quintana
<[email protected]> wrote:
I guess this is the final proof that given J and a sufficiently
POWERful
AGENDA, you can DO anything!
agenda=. ]^:(1:`(<'@.'))
(atop=. (<'@') agenda 0)
Or:
a=: ]^:(1:`(<'@.'))&0@<
atop=: a '@'
type 'a'
+----+
|verb|
+----+
type 'atop'
+-----------+
|conjunction|
+-----------+
The pun is different, of course.
Of course, the results are not necessarily consistent:
a&.> '@&'
+-+-+
|@|&|
+-+-+
a&> '@&'
@
But I suppose that since we already have inconsistent behavior for
displaying complex objects, maybe that's ok?
--
Raul
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