Sorry, did not explain that very well. Unlike most APL systems, Dyalog allows
the result of an expression to be a function/verb. So as J allows you to write:
add =: +
Dyalog allows
add←+
or add←{a+w}
Now, while ". in J seems not to want to return verbs or (and you CAN understand
its reluctance), the Dyalog execute primitive is less picky ("Explicit" in J
seems a rather odd beast too, even the term "special syntax" doesn't quite seem
sufficient to describe the workings of 3:0 :-)). So you can write:
add←exec'{a+w}'
... after which:
add/1 2 3
6
... and if you load up the dfns workspace which contains a "user-defined" rank
operator (http://www.dyalog.dk/dfnsdws/n_rank.htm):
1 2 (add rank 0 1) 2 2 {reshape} 10 20 30 40
11 21
32 42
Morten
-----Original Message-----
From: Raul Miller [mailto:[EMAIL PROTECTED]
Sent: 24. december 2007 14:09
To: Chat forum
Subject: Re: [Jchat] J readability
On Dec 24, 2007 4:53 AM, Morten Kromberg <[EMAIL PROTECTED]> wrote:
> Also, I don't see how 3: can be "more flexible than DFNS".
> I can use execute to turn a string into a DFN, which surely
> gives me the same functionality as 3: ?
I am not familiar enough with the syntactic capabilities of Dyalog's
execute to say for sure.
But, 3 : can be used in place, with modifiers or any other part
of J's execution capability.
Also, I tend to think of 3 : not as an entity to itself but as
an instance of the : operator. So things that hold for 3 :
also hold for 0 :, for 1 :, for 2 :, for 4 : and maybe for 13 :
(I do tend to think of u : as something not so related,
because u : does not treat strings, nor boxed strings,
nor 0 in the same fashion as the other : forms treat
them.)
Anyways, can you use ({thorn}DFN)/1 2 3 in Dyalog,
as a simple example? (Practical examples in
J are more likely to use the rank conjunction, but I do
not want to push this into territory I know is currently
irrelevant.)
--
Raul
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
