Missing builtins: evaluable \/1 (bitwise complement) and writeq/1 #33

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opened 2026-06-23 17:22:41 +00:00 by navicore · 1 comment

navicore commented

2026-06-23 17:22:41 +00:00

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Summary

Two standard ISO builtins are missing/unimplemented in plgc 0.3.0:

The unary arithmetic functor \/1 (bitwise complement) is not a
recognized evaluable functor for is/2.
writeq/1 is an undefined procedure.

Version

plgc 0.3.0.

Reproduction

Given any program file p.pl (e.g. p.):

$ plgc run p.pl --query "X is \ 0" --format text
Error: Runtime error: error(type_error(evaluable, /(\, 1)), Unknown arithmetic operator: \/1)

$ plgc run p.pl --query "writeq(foo)" --format text
Error: Runtime error: error(existence_error(procedure, /(writeq, 1)), Undefined procedure: writeq/1)

Expected (ISO)

X is \ 0 should evaluate to -1 (bitwise complement of the integer 0);
\/1 is a standard evaluable functor.
writeq/1 is a standard I/O builtin (writes a term with quoting so it reads
back).

Notes

The binary bitwise operators all work correctly: /\ (AND), \/ (OR),
xor, <<, >>. Only the unary complement \/1 is missing.
Filed together as both surfaced while authoring the
loglings arithmetic-depth
chapter; split if you'd prefer separate tracking.

## Summary Two standard ISO builtins are missing/unimplemented in `plgc 0.3.0`: 1. The **unary arithmetic functor `\/1`** (bitwise complement) is not a recognized evaluable functor for `is/2`. 2. **`writeq/1`** is an undefined procedure. ## Version `plgc 0.3.0`. ## Reproduction Given any program file `p.pl` (e.g. `p.`): ``` $ plgc run p.pl --query "X is \ 0" --format text Error: Runtime error: error(type_error(evaluable, /(\, 1)), Unknown arithmetic operator: \/1) $ plgc run p.pl --query "writeq(foo)" --format text Error: Runtime error: error(existence_error(procedure, /(writeq, 1)), Undefined procedure: writeq/1) ``` ## Expected (ISO) - `X is \ 0` should evaluate to `-1` (bitwise complement of the integer `0`); `\/1` is a standard evaluable functor. - `writeq/1` is a standard I/O builtin (writes a term with quoting so it reads back). ## Notes - The **binary** bitwise operators all work correctly: `/\` (AND), `\/` (OR), `xor`, `<<`, `>>`. Only the **unary** complement `\/1` is missing. - Filed together as both surfaced while authoring the [loglings](https://git.navicore.tech/navicore/loglings) arithmetic-depth chapter; split if you'd prefer separate tracking.

navicore referenced this issue from a commit

2026-06-23 19:59:06 +00:00

● All three issues are fixed, tested, and verified end-to-end. Full workspace test

navicore referenced this issue

2026-06-23 19:59:52 +00:00

● All three issues are fixed, tested, and verified end-to-end. Full workspace test #34

navicore commented

2026-06-23 20:00:33 +00:00

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#34

https://git.navicore.tech/navicore/patch-prolog/pulls/34