The debugger gets control at the end of a completed sentence, which may complete with error. Sentences in calling functions are in mid-execution. There is no way to resume a sentence in execution except by returning to it to let it finish.
Therefore, I think 'cut stack' must return to executing the calling function to let the suspended sentence complete before picking up in debug mode again. In your case the suspended sentence modifies z, and it might use the default value of (I. 0 0) as the value for the aborted function. I can't verify this at the moment but I bet something like this is happening. Henry Rich On Thu, Jun 16, 2022, 1:49 PM Raul Miller <[email protected]> wrote: > The f ing assert is a test on N which I introduced to prevent a > stack error. The stack error is a consequence of the state machine > defined by Kid -- it should be a tree, but was instead a directed > graph containing a loop. These details are relevant for understanding > what's happening here, but are a distraction from the problem. > > The problem here is that cutting back the stack updates z. And, at the > same time, it leaves the "current line" set to re-run the line which > was executed to update z. > > -- > Raul > > -- > Raul > > > On Thu, Jun 16, 2022 at 4:48 AM Henry Rich <[email protected]> wrote: > > > > The failing assert is line 0, right ? At that point local z has not been > > set. Do you have a public definition somewhere? > > > > (Still away from computer) > > > > Henry Rich > > > > On Wed, Jun 15, 2022, 11:43 PM Raul Miller <[email protected]> > wrote: > > > > > Sure, ... > > > > > > Kid=: 1 2,_ 1,:_ _ > > > Key=: 94 48 92 > > > Red=: 0 1 1 > > > N=: 4 > > > > > > clean=: 3 :0 > > > b=. (#y) > +/y e."1,9!:6'' > > > }.}:b #inv b# |:y > > > ) > > > > > > dbg=: 4 :0 > > > echo clean^:2 ":x;('#',":#$y);('$',":$y);'';y > > > ) > > > > > > > > > safeshow=: 3 : 0 > > > assert. 0 < N=:N-1 > > > 1 dbg z=. '' > > > assert. 1=#$z > > > 'l r'=. y{Kid > > > if. l<#Kid do. > > > 2 dbg z=. '(',(safeshow l),') ' > > > assert. 1=#$z > > > end. > > > 3 dbg z=. z,(":y{Key),':','BR'{~y{Red > > > assert. 1=#$z > > > if. r<#Kid do. > > > 4 dbg z=. z,' (',(safeshow r),')' > > > assert. 1=#$z > > > end.EMPTY > > > ) > > > > > > safeshow 0 > > > 1 #1 $0 > > > 1 #1 $0 > > > 3 #1 $4 48:R > > > 1 #1 $0 > > > 3 #1 $4 48:R > > > |assertion failure: safeshow > > > > > > After every assignment, z has a rank of 1, > > > > > > None of the assignments are from the result of safeshow. > > > > > > This suggests that cutting back the stack is implemented in an > > > inconsistent fashion -- at least some of the time it may complete > > > execution of the "current line" but despite that it leaves the code in > > > a state which suggests that that "current line" has yet to be > > > executed. > > > > > > Thanks, > > > > > > -- > > > Raul > > > > > > On Wed, Jun 15, 2022 at 2:49 PM Henry Rich <[email protected]> > wrote: > > > > > > > > Since I don't have a machine, I can't verify that anything is > wrong. You > > > > are failing in the third execution of show, using values that derive > from > > > > echo & might have rank 2. Why don't you type out the value of z at > each > > > > recursion? > > > > > > > > Henry Rich > > > > > > > > On Wed, Jun 15, 2022, 6:53 PM Raul Miller <[email protected]> > wrote: > > > > > > > > > That missing final z would not be ok for 'safeshow' to function > > > properly. > > > > > > > > > > But the problem here is not "how should 'safeshow' be changed to > > > > > function properly?" -- the problem here is "how do we use the > debugger > > > > > to help us understand how J functions?" or perhaps "what is wrong > with > > > > > the debugger? / how do we get the debugger to work properly? / how > do > > > > > we understand J?" > > > > > > > > > > Specifically, why is z rank 1 for assert and echo when the computed > > > > > result was rank 2? > > > > > > > > > > Thanks, > > > > > > > > > > -- > > > > > Raul > > > > > > > > > > On Wed, Jun 15, 2022 at 1:49 PM Henry Rich <[email protected]> > > > wrote: > > > > > > > > > > > > I am away from my machine, but I observe that the result of > safeshow > > > > > comes > > > > > > from echo, not z. Is that ok? > > > > > > > > > > > > Henry Rich > > > > > > > > > > > > On Wed, Jun 15, 2022, 7:03 AM Raul Miller <[email protected] > > > > > wrote: > > > > > > > > > > > > > I am running into a problem, in J903 and J904 -- I haven't yet > > > > > > > installed earlier versions of J on this machine. > > > > > > > > > > > > > > safeshow=: 3 :0 > > > > > > > assert. 0 < N=:N-1 > > > > > > > z=. '' > > > > > > > assert. 1=#$z > > > > > > > echo #$z > > > > > > > 'l r'=. y{Kid > > > > > > > if. l<#Kid do. > > > > > > > z=. '(',(safeshow l),') ' > > > > > > > assert. 1=#$z > > > > > > > echo #$z > > > > > > > end. > > > > > > > z=. z,(":y{Key),':','BR'{~y{Red > > > > > > > assert. 1=#$z > > > > > > > echo #$z > > > > > > > if. r<#Kid do. > > > > > > > z=. z,' (',(safeshow r),')' > > > > > > > assert. 1=#$z > > > > > > > echo #$z > > > > > > > end. > > > > > > > ) > > > > > > > > > > > > > > Kid=: 1 2,_ 1,:_ _ > > > > > > > Key=: 94 48 92 > > > > > > > Red=: 0 1 1 > > > > > > > N=: 3 > > > > > > > safeshow 0 > > > > > > > 1 > > > > > > > 1 > > > > > > > 1 > > > > > > > |assertion failure: safeshow > > > > > > > > > > > > > > Now, there's a problem here with my data which triggers the > > > assertion > > > > > > > -- Kid should not contain any duplicate values other than _. > But > > > > > > > that's not what I am concerned with here. > > > > > > > > > > > > > > In Jqt, I enable debugging (control-K) and when the debugger > pops > > > up > > > > > > > on the assert, I go back to the previous stack frame, and I > find > > > that > > > > > > > z has rank 2, instead of rank 1. > > > > > > > > > > > > > > Specifically, it has the value '48:R',' (',:' ' > > > > > > > > > > > > > > So, now I am trying to figure out what's gone wrong. > > > > > > > > > > > > > > Conceptually, I could accept that z was being modified by > virtual > > > > > > > block handling -- except there's no update to z which would > have > > > given > > > > > > > it a rank 2 value. > > > > > > > > > > > > > > Another possibility here is that there's something specifically > > > wrong > > > > > > > with my machine. So: can anyone else reproduce this issue? > > > > > > > > > > > > > > And, ... the next most likely possibility is that there's > something > > > > > > > wrong with the J engine itself. > > > > > > > > > > > > > > Anyways, I'd like to get someone else's perspective here. > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > -- > > > > > > > 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 > > > > > > ---------------------------------------------------------------------- > > > > > 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
