weird behavior of Dyalog 18.0 under Big Sur

[dyallaz]

My APL session runs with ⎕IO=0, as set by the configurations files. No index problems until Wednesday 17 Feb. at 19:00. Since then, when I execute some recently programmed dfns, I receive the message "INDEX ERROR." Looking at the process closer, one can notice that the ⎕IO changes to 1 by entering functions. But no such assignment is included in the function body.

This is infuriating, all the more so as I am a dogmatic supporter of index origin zero.

The attachment shows a simple example:

[dyallaz]

From midnight between 17 and 18 February, the APL session seems to behave properly again. I just closed APL at 8 o'clock pm and put the Mac Mini to sleep for 4 hours. Looks like an efficient cure ...

[AndyS|Dyalog]

Is it possible that you had a stop control set on ∆MinBlanks[0] ?

The code for ]display runs with ⎕io set to 1, and if I try

      ⎕fx'r←foo r' '⍝'
      0 ⎕stop 'foo'
      ]display foo 1

foo[0]
      ⎕io 
1

(note the blank line after the call to ]display, and the fact that the output includes "foo[0]".

And when you call )sic then the stack is cleared and ⎕io returns to 0.

When you next )loaded the workspace, then if you hadn't saved it with the stop control set, the output would not be as above.

If this is not the case, then you're welcome to send us a copy of the workspace and we'll see if we can work out what's going on.

[dyallaz]

Yes, I had stops in the function I was constructing. In the development phase you need them, especially to check index errors! I put the stops as red dots in the edit window. Things got better when I tested in the following form:

x←∆MinBlanks C
]display x C

Anyway, that "]display" forces its settings before the function whose result it shall display exits, is not gentlemanlike, to say the least.

My APL runs on a Mac Mini with Apple silicon, since January 2021. Once I couldn't leave the interpreter, which was using 80% of CPU-ressources as "busy idle process". The APL window was frozen. It didn't appear in the Force Quit menu either. I had to restart the system. Sometime, the 80% are used even after an exit with )off. The next time I start the interpreter, another 80% is added to Dyalog APL use of CPUs, as shown on Activity Monitor.

Many thanks for your speedy and informative answer.

[dyallaz]

Now Dyalog APL 18.0 runs perfectly. I changed few configuration settings. The problem with the ghost processes (hidden background session remaining after quit) appeared, I think, because I misspelled some file name in one of the configuration files.

I am to blame.