ReadFile broken on DuckDB

[MikeBeller]

Hi! I'm new to Logica. Looking to use datalog for some AI-related work I am doing right now. Logica is a really intriguing project! Thanks for making it available.

I believe there is a bug in the duckdb implementation of ReadFile:

 logica - run Inp <<<'Inp() = ReadFile("input.txt");'
Traceback (most recent call last):
  File "/Users/mike/tmp/logi/.venv/bin/logica", line 10, in <module>
    sys.exit(run_main())
             ~~~~~~~~^^
  File "/Users/mike/tmp/logi/.venv/lib/python3.13/site-packages/logica/logica.py", line 345, in run_main
    main(sys.argv)
    ~~~~^^^^^^^^^^
  File "/Users/mike/tmp/logi/.venv/lib/python3.13/site-packages/logica/logica.py", line 290, in main
    cur = connection.sql(formatted_sql)
_duckdb.CatalogException: Catalog Error: Scalar Function with name pg_read_file does not exist!
Did you mean "pg_has_role"?

The implementation, in https://github.com/EvgSkv/logica/blob/0ce1da4576c1bbaa524c8b0daf5a98ee7b3bd766/compiler/dialect_libraries/duckdb_library.py#L50 seems to have been copied from the PostgreSQL implementation. Duckdb does not have a pg_read_file function, but it does have a read_text function. I tried just swapping the functions in the duckdb_library.py source, butread_text is a table function in duckdb, so that just produces a different error.:

_duckdb.BinderException: Binder Error: Function "read_text" is a table function but it was used as a scalar function. This function has to be called in a FROM clause (similar to a table).

As yet, I don't understand logica well enough to understand what the fix is, but I'm guessing its pretty simple.

Regards
Mike Beller

[EvgSkv]

Welcome, @MikeBeller !

Thank you for heads up!

Since read_text is a table function you can call it like so

$ python3 logica.py - run Inp <<<'Inp(content) :- `(read_text("../input.txt"))`(content:);'
+-------------+
| col0        |
+-------------+
/˙˙˙˙˙˙˙˙˙˙˙˙˙\
| hello world |
| aaa         |
|             |
|             |
\............./
+-------------+

But I don't find this pretty, so I did fix the ReadFile duckdb function (in main), so now it works:

$ logica - run Inp <<<"
Inp(result:,
    size: result.size,
    content: result.content,
    filename: result.filename,
    lines: Split(result.content, '\n')) :-
  result =  ReadFile('../input.txt');
"
+-----------------------------------------------------------------------------+------+-------------+--------------+--------------------------------+
| result                                                                      | size | content     | filename     | lines                          |
+-----------------------------------------------------------------------------+------+-------------+--------------+--------------------------------+
/˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙|˙˙˙˙˙˙|˙˙˙˙˙˙˙˙˙˙˙˙˙|˙˙˙˙˙˙˙˙˙˙˙˙˙˙|˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙\
| {'size': 17, 'content': 'hello world\naaa\n\n', 'filename': '../input.txt'} | 17   | hello world | ../input.txt | ['hello world', 'aaa', '', ''] |
|                                                                             |      | aaa         |              |                                |
|                                                                             |      |             |              |                                |
|                                                                             |      |             |              |                                |
\.............................................................................|......|.............|..............|................................/
+-----------------------------------------------------------------------------+------+-------------+--------------+--------------------------------+

Please let me know if you have questions or hit any other issues!

[MikeBeller]

Thank you @EvgSkv . I appreciate the quick fix!

Note: I was aware there was a ``...`` syntax from seeing it used on the the logica.dev home page, but I couldn't find it documented anywhere. After you sent this, I searched through the documentation in the github repo, and found that it is explained in syntax.md (the BNF page). But that syntax.md does not appear to be linked to the main body of documentation (e.g. not accessible via the website) as far as I can tell.

-Mike