Compatibility

What cl-prolog promises to keep working, and what it deliberately does not.

Supported surface

Changes preserve the documented cl-prolog public API, the CPS query surface, and the separation between rule data and solver logic. Specifically:

• documented public cl-prolog behavior, as described in API Reference
• macro-first rule definition and CPS query semantics, as described in Rule DSL and Querying
• reproducible packaging and example execution through the flake

Not supported

• Undocumented %... internals. Symbols prefixed with % are private. They are not exported, they are not in API Reference, and they change without a changelog entry.
• Full ISO Prolog behavior. This is a focused Prolog runtime, not a standalone ISO system. Semantics records which parts of ISO/IEC 13211-1 the engine implements and where it departs; the INRIA conformance corpus in t/iso/ measures how far that goes.
• Unbounded relational enumeration in every argument direction. A goal that is relational in one mode is not guaranteed to enumerate in all of them. Builtin Goals states the modes each builtin supports.

Implementation support

SBCL only. sb-posix is used directly and CI runs SBCL exclusively, so portability to other Common Lisp implementations is neither claimed nor verified.

Versioning

The :version in cl-prolog.asd is the single source of truth: flake.nix reads it, and the release workflow refuses to publish a tag that disagrees with it. Breaking changes to the supported surface above are recorded under their release heading in CHANGELOG.md.