Just in case I'm not the one misunderstanding, is there a counter example to
"There is no possible f such that f N differs from f N =: (anonymous noun)" ----- Original Message ----- From: Henry Rich <[email protected]> To: [email protected] Sent: Wednesday, October 5, 2016 3:58 PM Subject: Re: [Jprogramming] Early assignment WAS: Non-mutable arrays All I can say is, It doesn't work that way. (You have 2 statements, each with 2 versions. All 4 statements are false.) Henry Rich On 10/5/2016 10:10 AM, 'Pascal Jasmin' via Programming wrote: > >> Assignment to (a) increments the usecount, giving (a) a usecount of 2. > I think in the expression, > > > f N =: 1 2 3 NB.(where 1 2 3 is anonymous noun/result) > > > N or 1 2 3 has a use count of 1 here, right after the assignment. (more > precisely the anonymous "usecount" is freed) > > There is no possible f such that f N differs from f N =: (noun). ie. the line > is always identical to the 2 lines > > N =: (noun) > f N > > > > > ----- Original Message ----- > From: Henry Rich <[email protected]> > To: [email protected] > Sent: Tuesday, October 4, 2016 10:42 PM > Subject: Re: [Jprogramming] Early assignment WAS: Non-mutable arrays > > Yes, you're right, I misanalyzed. It goes like this: > > 1 2 3 starts with a usecount of 1, and a mark to indicate that the > usecount should be decremented when the sentence completes. [When the > usecount is decremented to 0 the block is freed]. > > Assignment to (a) increments the usecount, giving (a) a usecount of 2. > That makes (a) ineligible for in-place operations. > > > Henry Rich > > > On 10/4/2016 10:21 PM, 'Pascal Jasmin' via Programming wrote: >> this didn't seem to work in beta 12 (latest all in one installer) >> >> >> >> >> ----- Original Message ----- >> From: Henry Rich <[email protected]> >> To: [email protected] >> Sent: Tuesday, October 4, 2016 10:14 PM >> Subject: Re: [Jprogramming] Early assignment WAS: Non-mutable arrays >> >> Yes, this is executed in-place. >> >> In general, an assignment to a name whose value is not in use in another >> name causes that value to become eligible for in-place execution (with >> the possibility of early assignment) as long as the execution stack >> contains nothing beyond the value to be assigned. >> >> a=: ('b' ,~ 4,~])a =: 1 2 3 NB. in place >> >> (a=: ('b' ,~ 4,~])a =: 1 2 3) [ 1 NB. not in place >> >> Henry Rich >> >> >> >> >> >> On 10/4/2016 9:28 PM, 'Pascal Jasmin' via Programming wrote: >>> I made different suggestions in my beta post. namely, this expression >>> should also be optimized: >>> >>> >>> a=: ('b' ,~ 4,~])a =: 1 2 3 >>> >>> if possible, early assignment should also apply in scripts (even if through >>> tacit expressions). >>> >>> In general though, I think the advice "assign to new name to be safe", >>> works ok, but above line in console can be edited and reapplied with >>> consistent results. >>> >>> >>> >>> >>> >>> ----- Original Message ----- >>> From: Henry Rich <[email protected]> >>> To: [email protected] >>> Sent: Tuesday, October 4, 2016 7:25 PM >>> Subject: [Jprogramming] Early assignment WAS: Non-mutable arrays >>> >>> The whole point of operation in place is to avoid having to copy an >>> in-placeable argument; copying the argument would not be a good solution. >>> >>> After hearing the screams and dodging the dead cats, I have some proposals: >>> >>> 1. Early assignment (which is what we'll call the act of assigning an >>> intermediate value to a name that is about to be reassigned) will apply >>> only for sentences executed from an explicit definition. That will >>> eliminate the most likely source of confusion, which is erroneous >>> sentences typed into the console during debugging and exploration. >>> >>> For discussion here: >>> >>> 2. Early assignment could be disabled for sentences executed between >>> try. and catch. This would apply only to sentences from the same >>> execution that contains the try. Verbs called from within the try. >>> block will continue to have early assignment enabled as specified by the >>> setting of 9!:52''. >>> >>> 3. Error message text could be modified to indicate that an early >>> assignment occurred. I worry about this because existing code might >>> rely on the text of messages. >>> >>> Henry Rich >>> >>> >>> On 10/4/2016 3:01 PM, Louis de Forcrand wrote: >>>> I second Raul; the behaviour described is very counter-intuitive. Maybe >>>> add a third setting to 9!:53 which copies a at the start of a tacit verb >>>> involving in place operations? >>>> >>>> Also, what is the current (j804) behaviour when an in-place ammend fails? >>>> Since there's only one operation, if it fails a shouldn't be modified >>>> should it? >>>> If so, copying a at the beginning of a tacit verb containing more than one >>>> in-place operation (IPO) should always be faster than the current >>>> implementation, since copying would only be needed when two or more IPOs >>>> take place. >>>> >>>> Louis >>>> >>>>> On 04 Oct 2016, at 07:15, Raul Miller <[email protected]> wrote: >>>>> >>>>> When there are many verbs involved, it seems like the relative cost to >>>>> make a copy of the original at the start should be minor. >>>>> >>>>> Thanks, >>>>> >>>>> -- >>>>> Raul >>>>> >>>>> >>>>>> On Mon, Oct 3, 2016 at 10:52 PM, Henry Rich <[email protected]> wrote: >>>>>> The shape is just the tip of the iceberg. If the verb in question were >>>>>> m}, >>>>>> there would be no way to restore (a). >>>>>> >>>>>> And in general, many in-place verbs may have executed before the error. >>>>>> The >>>>>> original (a) may be long gone. >>>>>> >>>>>> If you foresee this as a problem, you should execute 9!:53(0) to turn off >>>>>> early assignment. >>>>>> >>>>>> Henry Rich >>>>>> >>>>>>> On 10/3/2016 10:34 PM, Raul Miller wrote: >>>>>>> >>>>>>> There are two reasons to be concerned about the value of a in the error >>>>>>> case. >>>>>>> >>>>>>> The minor one is error recovery. This is a simple example, and easy to >>>>>>> understand. What happens, though, when someone uses try./catch. with a >>>>>>> large code base? This issue would not be easy to isolate, nor will it >>>>>>> be easy to understand. >>>>>>> >>>>>>> A bigger issue is the one you mentioned here: debugging. When >>>>>>> debugging code which takes a long time to run, you will at times want >>>>>>> to fix the issue and continue, rather than burning the time necessary >>>>>>> to restart from the beginning. >>>>>>> >>>>>>> And, also, this seems like it will be hard to explain and at the same >>>>>>> time distract from issues which are more important. >>>>>>> >>>>>>> But keep in mind that I am not recommending the (a=:0)](a) mechanism >>>>>>> for this example. I made that suggestion for hypothetical cases. >>>>>>> >>>>>>> I am instead recommending that the shape of a be saved somewhere and >>>>>>> that a have its shape set to what it originally was, in the error >>>>>>> case. >>>>>>> >>>>>>> Is there some reason why you think that restoring a's shape in the >>>>>>> error case is not a viable approach here? >>>>>>> >>>>>>> Thanks, >>>>>> ---------------------------------------------------------------------- >>>>>> 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 > ---------------------------------------------------------------------- > 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
