I am mostly thinking that flexibility would be good. But there are
other possible optimizations:
1. An argument to a verb is known to be sorted
2. An argument to a verb is a hash table
3. An argument is known to be 'read-only', and can skip some recopying
4. A result is known to be discardable immediately
5. An expression is guaranteed not to perform any assignments to
anything but nouns
6. A verb is guaranteed not to create any names except ones appearing in
name =.: assignments
(2) would require that the hash table become a primitive datatype, which
I think is something that should be discussed.
There are many things we might do, and as long as we are adding a
mechanism for directing interpretation, we ought to make it extensible.
Henry Rich
On 3/22/2016 11:02 AM, Thomas Costigliola wrote:
What kind of possibilities where you thinking of? Things not related
to $: as well?
On 03/21/2016 07:19 PM, Henry Rich wrote:
Would it make sense for O. to be a conjunction where v is a bitmask
indicating the type of optimization requested? There might be many
possibilities.
Henry Rich
On 3/21/2016 7:15 PM, Jose Mario Quintana wrote:
One reason might be that Jx's adverb O. expects a verb in
tail-recursive
form and bad things might happen if it is not and currently it cannot
determine automatically if it is. Jx is not for the faint of heart and
will stay there but I am not sure about J Unbox or the official
interpreter.
On Mon, Mar 21, 2016 at 6:21 PM, Pascal Jasmin <[email protected]>
wrote:
Can't think of a reason why we wouldn't want this in the official
interpreter
----- Original Message -----
From: Jose Mario Quintana <[email protected]>
To: Programming forum <[email protected]>
Sent: Monday, March 21, 2016 9:54 AM
Subject: Re: [Jprogramming] Tail recursion (bug hijack)
Right, I never saw or found a satisfactory coding of a genuine while
conjunction. However, in Jx one can afford, thanks to Thomas'
effective
implementation of the adverb O. for the Jx interpreter, to do the
unthinkable: code a genuine while conjunction recursively! That is, a
conjunction wTCO such that,
u wTCO v
]`($:^:(1:`u))@.v O.
This is how it works for the case at hand,
whileO =: v1@:(v0 wTCO (-. @: v2)) NB.
power i.20
0 7 8 9 10 11 12 13 14 15 16 17 18 19
recursive i.20
0 10 11 12 13 14 15 16 17 18 19
whileO i.20
0 10 11 12 13 14 15 16 17 18 19
recursiveO i.20
0 10 11 12 13 14 15 16 17 18 19
stp=. ([ ((<;._1 '|Sentence|Space|Time|Space * Time') , (,
*/&.:>@:(1
2&{))@:(] ; 7!:2@:] ; 6!:2)&>) (10{a.) -.&a:@:(<;._2@,~) ]) ".@:('0 :
0'"_)
Y=. i.111
stp 11
recursive Y
whileO Y
recursiveO Y
)
┌──────────────┬──────┬────────────┬────────────┐
│Sentence │Space │Time │Space * Time│
├──────────────┼──────┼────────────┼────────────┤
│ recursive Y│222592│0.0475173844│10576.9896 │
├──────────────┼──────┼────────────┼────────────┤
│ whileO Y│36992 │0.0397433474│1470.18591 │
├──────────────┼──────┼────────────┼────────────┤
│ recursiveO Y│37376 │0.0434088376│1622.44871 │
└──────────────┴──────┴────────────┴────────────┘
On Sat, Mar 19, 2016 at 2:39 PM, Dan Bron <[email protected]> wrote:
Louis wrote:
The problem is that u^:v^:_ y terminates
either when 0 = v y OR when y -: u y .
Yeah, this has bitten us all at one time or another. The traditional
solution is to add a little tag to the data structure which you
mutate
(along with the normal processing) at every iteration. Most
commonly we
just do (u@:>@:{. ; -.&.>@:{:)^:v^:_ y ; 0 (adjusting the boxing
logic
as
needed).
I asked for better alternatives than this a few years back [1],
but we
didn’t come up with anything compelling.
-Dan
[1] J Programming thread, “Limit limitation, Oct 2009:
http://www.jsoftware.com/pipermail/programming/2009-October/016513.html
<
http://www.jsoftware.com/pipermail/programming/2009-October/016513.html>
----------------------------------------------------------------------
For information about J forums see
http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
