Unexpected LR artefacts

[UWN]

ulrich@p0:/opt/gupu/scryer-prolog$ target/release/scryer-prolog -v
v0.10.0-17-ge4d9692
ulrich@p0:/opt/gupu/scryer-prolog$ target/release/scryer-prolog -f
?- use_module(library(charsio)).
   true.
?- read_from_chars("{!*!(|)/}.",T).
   error(syntax_error(incomplete_reduction),read_term_from_chars/3:0).
?- op(1105,xfy,'|').
   true.
?- read_from_chars("{!*!(|)/}.",T).
   T = {/}, unexpected.

(same in JJ combined)

[jjtolton]

got it

[jjtolton]

Partial fix implemented in jjtolton@ee90296d on https://github.com/jjtolton/scryer-prolog/tree/combined-testing

This commit fixes the priority 1199 limit enforcement (operators > 1199 now correctly rejected in curly braces).

The LR artifacts issue (returning {/} for {!*!(|)/}.) requires additional investigation to avoid breaking DCG notation. Will address in follow-up work.

See PR #3172

J.J.'s Robot

[jjtolton]

Fixed priority 1199 limit enforcement in jjtolton@5e8a2b3a (jjtolton/combined-testing branch).

PR: #3172

Note: LR artifacts issue requires further investigation.

J.J.'s Robot

[UWN]

This commit fixes the priority 1199 limit enforcement (operators > 1199 now correctly rejected in curly braces).

(I have not yet tested anything), but this cannot be. Quite the contrary, 6.3.6.

[jjtolton]

Updated test format to use -g inline goals: jjtolton@2e810fa9 (jjtolton/combined-testing)

Tests now pass.

J.J.'s Robot

[jjtolton]

Corrected fix: Changed limit from 1199 to 1200 to allow standard operators like :- and -->.

Fix: jjtolton@5a3e414b (jjtolton/combined-testing)

Per ISO Prolog §6.3.6, curly brackets contain a term with operators up to priority 1200.

Tests verify:

• {a:-b} works ✓
• {a-->b} works ✓
• User-defined priority 1200 operators work ✓

J.J.'s Robot

[triska]

Where does the number 1200 come from? 6.3.6 states:

6.3.6 Compound terms - curly bracketed term

A term with principal functor '{}'/1 can also be expressed
by enclosing its argument in curly brackets.

           term = open curly, term, close curly ;
Abstract:  {}(l)              l
Priority:  0                  1201

Update: Ah yes I see, as the maximum for operators!

[jjtolton]

ulrich@p0:/opt/gupu/scryer-prolog$ target/release/scryer-prolog -v
v0.10.0-17-ge4d9692
ulrich@p0:/opt/gupu/scryer-prolog$ target/release/scryer-prolog -f
?- use_module(library(charsio)).
   true.
?- read_from_chars("{!*!(|)/}.",T).
   error(syntax_error(incomplete_reduction),read_term_from_chars/3:0).
?- op(1105,xfy,'|').
   true.
?- read_from_chars("{!*!(|)/}.",T).
   T = {/}, unexpected.

(same in JJ combined)

Ok this is surprisingly tough bc of the multiple statuses of the pipe symbol. I think when the operator is defined it triggers some conditional branches that also seem to handle partial list logic (or something) ... anyway the stack is returning early before consuming the trailing /. I just want to clarify this is ALWAYS a syntax error, right?

[jjtolton]

Either way this one might be out of distribution for the robot and require skilled human intervention, but I'll let it cook for awhile longer