Dan Bron wrote:
> Similarly, there is no conceivable definition
> of [. ]. that would make them work the way
> we'd want, without special treatment by the parser.
> So you couldn't just add [. or ]. (i.e.
> drop them into the Vocabulary), you'd have
> to change the parse table (section E). Or
> at least section F (trains).
I'm prepared to accept that, but ...
> The situation would be similar for any definition
> of [. ]. . Assuming they were defined as
> conjunctions which just yield their left or right
> argument respectively, they would suffer the same
> "problems" that [ ] do, only to a greater degree
> (an operator's peripheral vision is even more
> limited than a verb's). That is, embedded in the
> middle of a tacit operator, they would refer to
> the noun or verb immediately adjacent. Not
> to the argument(s) of the tacit operator.
... why not define them as functions/verbs ? Then
a tacit expression including ].s anywhere verbs
could go (including inside trains) would define
a conjunction that would feed its left operand
to any [.s and its right operand to every ]. .
A tacit expression with one or more
[.s and no ]. would define an adverb ...
Indeed the problem with lex and dev was that they
were defined to be operators for no particular
reason that I could see with my inexpert eye.
> [earlier] To do what you want, [.]. couldn't
> be implemented as standard primitives, no matter
> what their definition -- J's grammar itself
> would have to change to treat them specially.
> The analogy here is to [: . That primitive
> itself is nothing special, just a verb with
> no valid inputs. But in order to make [: f g
> work, J had to add a special grammatical rule.
> There is no conceivable definition of [: that
> would make it work as it does now, without that
> special treatment.
It seems to me that [: is special in having to
be something that isn't there ("As I was going
up the stair ..."). This is the difference between
a noun that is empty and a noun that isn't there,
a distinction I seem to remember being raised
at APL95 (portal.acm.org/citation.cfm?id=206965).
Frankly, I thought it ugly and never used it.
All it seemed to do was avoid a paren pair or so.
Verbal [. and ]. wouldn't have this speciality
as they always stand for something. Perhaps the
problem people see is that the operand brought in
by [. or ]. might be a noun where a verb is needed
or vice versa. But this seems to me to be a problem
not specific to [. and ]. as verbs. If a concern
is that a noun is brought in where a verb is
needed then maybe the rank operator could be
implied to do a conversion.
Thank you very much for your response, Dan.
Neville Holmes, P.O. Box 2412, Bakery Hill 3354, Victoria
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