^ ^                 ^ ^
=(o.o)=  ~byakuren  =(o.o)=
  m m                 m m

ISO Conformance (flowlog.c)

Flowlog targets ISO/IEC 13211-1 behavior: if you write portable ISO Prolog, it should run the same here as in other ISO-focused systems.

This document describes the conformance strategy for Flowlog built from flowlog.c.

What “ISO compliant” means here

ISO/IEC 13211-1 defines the language and its built-in predicates. It does not define what an interactive REPL must look like.

Flowlog aims to match ISO semantics for:

• Terms, unification, and control constructs (SECTIONS 12/14/15/22/23/24)
• Arithmetic evaluation and ISO error conditions (SUBSECTION 15.2 and SECTION 19)
• Dynamic database predicates (asserta/1, assertz/1, retract/1, abolish/1, clause/2, current_predicate/1, …) (SECTION 13)
• Streams and term I/O (open/3, close/1, read_term/3, write_term/3, set_input/1, set_output/1, …) (SECTION 08 and SUBSECTION 17.5)
• Prolog flags (current_prolog_flag/2, set_prolog_flag/2) and per-call I/O options (SECTION 05.4 and SECTIONS 22/23/24)

Code references (section markers in flowlog.c):

• Terms, unification, and ordering: SECTIONS 12/14/15/16
• Arithmetic evaluation and numeric errors: SUBSECTION 15.2 and SECTION 19
• Dynamic database: SECTION 13
• Streams and term I/O: SECTION 08 and SUBSECTION 17.5
• Prolog flags and CLI defaults: SECTION 05.4 and SUBSECTION 26.1

The predicate/flag checklist is tracked in:

• ISO_CHECKLIST.md

Non-ISO behavior (top-level UI)

These are deliberate UX choices for the binary and are not part of the ISO language definition:

• The TTY REPL supports interactive ; (next), f (next 5), and a (stream all) like classic Prolog. In non-TTY mode, Flowlog prints all solutions for scripting.
• The REPL supports the common top-level consult shorthand ([file].) as a convenience for loading source files.
• Parallelism flags are Flowlog extensions; they can change ordering when enabled (see PARALLELISM.md).

Suites

This directory includes:

• A regression runner in tests/
• An INRIA ISO suite runner in tests/
• A quad (QUAD - Query Using Answer Description) conformance runner in tests/ (see QUAD_TESTS.md)

Notes:

• The suite is downloaded into build/inria_suite/.
• tests/inria/setup_inria_suite.sh applies a couple of small, documented normalizations so the suite matches modern ISO-focused systems.
• The conformance runner forces classic mode (--engine interp --parallel-profile off) so suite expectations about ordering/side-effects match ISO-focused interpreters.
• You can also run the suite under --engine wam (or --engine wamvm) by setting FLOWLOG_ENGINE=wam (or FLOWLOG_ENGINE=wamvm); this is useful for verifying WAM engine coverage.
• To ensure the wamvm engine does not fall back to wam, set FLOWLOG_WAMVM_REQUIRE_VM=1 (VM-only mode). Flowlog also provides make inria-wamvm-vmonly to lock this in.

Interpreting warnings

Some suite files temporarily set unknown=warning and intentionally call missing predicates to check the flag’s behavior. Flowlog prints a warning in that case; the suite still passes.

The runner tests/run_inria_suite.sh suppresses per-test stderr by default to keep output clean. To show warnings/errors for every file:

• FLOWLOG_INRIA_SHOW_STDERR=1 make inria

What conformance does not guarantee

Passing the INRIA suite is a strong signal, but it is not a mathematical proof of full ISO compliance. If you find a behavioral mismatch with another ISO-focused system, please reduce it to a small repro program and add it to tests/.