Dyalog Forums

Posted: **Fri Nov 15, 2019 7:10 am**

Here is some odd INTERPRETER behaviour!!! I'm generating a SIGNAL with an unusual, but legit, unicode character: ⃠ ⎕UCS 128683 (hex 1F6AB) (Note: I replaced Unicode 128683 with 8416 (which looks similar) in this post, because the former triggered an SQL error in the FORUM on SUBMIT). Dyalog APL on MacOS decides there's a rank error in the ⎕SIGNAL message string (left arg), even though said string checks out as a proper character vector.

Code: Select all

)clear
clear ws
      ERRch←⎕UCS 128683
      ERRch
 ⃠      ⍝ a non-combining DO NOT ENTER (error) Symbol; contrast  ⃠ 8416
      (ERRch,'Help me!')⎕SIGNAL 11     ⍝ Bad interpreter?
RANK ERROR: A signalled message must be a character vector or scalar
      (ERRch,'Help me!')⎕SIGNAL 11
                        ∧
      ('Help me!') ⎕SIGNAL 11      ⍝ Expected behaviour
Help me!
      ('Help me!')⎕SIGNAL 11
                  ∧
      m←ERRch,'Help me!'           ⍝ Same song, next verse
      m
 ⃠Help me!                         
      m ⎕SIGNAL 11                  ⍝ Same refrain
RANK ERROR: A signalled message must be a character vector or scalar
      m ⎕SIGNAL 11
        ∧
      (m~⎕UCS 128683) ⎕SIGNAL 11    ⍝ Remove the symbol. All is well.
Help me!
      (m~⎕UCS 128683)⎕SIGNAL 11

Lesson learned: Don't use cute characters in error messages.
Here are the system details:

Interpreter:
Version: 17.1.36845
Platform: Mac-64
Edition: Unicode/64
Date: Aug 15 2019 at 00:08:18
Version: 4.2.3437
Platform: MacIntel
Date: 2019-08-13 14:55:17 +0200
Git commit: 691f47856e05a36f70847313b23e061a0cf95392

Posted: **Sat Nov 16, 2019 1:28 pm**

Hi, seemingly the []DR of the left argument cannot be 32 bit character:

      ⎕DR ⎕UCS 65535
160
      ⎕DR ⎕UCS 65536
320
      ((⎕UCS 65535),'Help me!')⎕SIGNAL 11 
�Help me!
      ((⎕UCS 65535),'Help me!')⎕SIGNAL 11
                              ∧
      ((⎕UCS 65536),'Help me!')⎕SIGNAL 11
RANK ERROR: A signalled message must be a character vector or scalar
      ((⎕UCS 65536),'Help me!')⎕SIGNAL 11
                              ∧

-Veli-Matti

Posted: **Sat Nov 16, 2019 10:14 pm**

Thanks. That's a very good summary of the problem. I had tried Chinese characters (like UCS 20004), but I forgot, those are 16-bit chars and work fine.

Even the other "DO NOT ENTER" ⎕UCS 8416 misbehaves on output depending on what's before or after it, sometimes appearing as blanks and other times as defined, but that may relate to (non-standard) behaviour of combining characters in Dyalog's terminal output routines.

Posted: **Tue Nov 19, 2019 11:46 am**

I have a two part answer:

"That's bonkers" was the response to the RANK ERROR - we'll replace that with a DOMAIN ERROR in the next version of Dyalog APL.
Indeed the interpreter does not support 32-bit characters in ⎕SIGNAL. I've raised an RFE to ask for this, but there's no guarantee that we'll ever implement this.

Posted: **Tue Nov 19, 2019 11:05 pm**

Thanks for this. It would be great if the reference guide could point out the limitation. Documentation that matches the actual behaviour pays for itself many times over.

Dyalog Forums

Interpreter bug with ⎕SIGNAL: a spurious RANK ERROR.

Interpreter bug with ⎕SIGNAL: a spurious RANK ERROR.

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Re: Interpreter bug with ⎕SIGNAL: a spurious RANK ERROR.

Re: Interpreter bug with ⎕SIGNAL: a spurious RANK ERROR.

Re: Interpreter bug with ⎕SIGNAL: a spurious RANK ERROR.