[developers] Bug in interactive unification

[John Carroll]

Hi Guy, thanks for the bug reports! Responses below.

On 13 Nov 2020, at 11:34, Guy Emerson <gete2 at cam.ac.uk<mailto:gete2 at cam.ac.uk>> wrote:

Hi John, Woodley, and Stephan,

Thank you all for your fast responses!  This has been really helpful.

I have come across two further small bugs, both to do with type names consisting entirely of numeric characters.  Such names are allowed internally in the LKB, and in terms of unification, they seem to behave exactly as I expect them to.  I couldn't find documentation suggesting that numeric characters should be treated differently.

You're right - types with all-numeric names should work fine. At http://moin.delph-in.net/TdlRfc the relevant clause is

  Identifier := /[^\s!"#$%&'(),.\/:;<=>[\]^|]+/

which allows any characters apart from whitespace and a few other non-alphanumerics.

However:

(1) in the View>Expanded type pop-up window, a string of numeric characters gives the message "Not defined - try again.", even if the type is defined.  (When the pop-up window shows a drop-down instead of a text box, such types appear in the list.)

Yes, this is a bug in the LKB. I'll email you a patch file which you can load to fix it - and I'll commit the changes to the LOGON and FOS branches of the LKB.

(2) Displaying such a type causes LUI to crash.  For example, a type named "1" causes a crash, with the following in the log file (where the value of RESULT is 1):

process_complete_command(): `
avm 3 #D[null-with-push-1-here RESULT: #D[1 REST: NULL]] "null-with-push-1-here - expanded"
 '

Type of dag was not a symbol or string (type 2)

This error message comes from LUI, and I think it needs fixing there.

John


Best,
Guy


Am Mi., 11. Nov. 2020 um 21:52 Uhr schrieb Stephan Oepen <oe at ifi.uio.no<mailto:oe at ifi.uio.no>>:
hi john:

> Aha, the constraint object in your LUI log has unbalanced brackets. Guessing which bracket is wrong, I've changed another LKB robust unifier function, and attach a new version of the file debug-unify2-patch.lsp

many thanks for the quick diagnostics and fixes!  i looked over both
your patches, and they seem like just the right fix to two genuine
bugs that have been lurking (for the past sixteen or so years :-) in
the interactive unifier behind the LUI drag-and-drop interface.  i
have just picked them up (and added my own fix for the LUI display of
atomic dags) and committed these changes to both the LOGON and FOS
repositories.

best wishes, oe

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