patch-prolog

A Prolog compiler for linting generative AI output. You write rules in standard Prolog, compile them into a self-contained Rust binary, and query that binary at runtime — no interpreter, no file loading, no runtime dependencies.

How It Works

1. Write Prolog rules (.pl files) in the knowledge/ directory
2. cargo build compiles them into the binary via build.rs
3. Run the binary with a query — it resolves against the embedded knowledge base

The rules are baked in. The binary is the program.

Example: Lint an AI-Generated Schema

The examples/linting.pl file defines rules for checking AI-generated API schemas:

% Flag sensitive fields that should not be exposed
violation(Field, sensitive_field) :-
    field(user, Field, _),
    sensitive(Field).

sensitive(ssn).
sensitive(password).

To compile and run it:

# Copy rules into the knowledge base
cp examples/linting.pl knowledge/

# Compile — rules are baked into the binary
cargo build --release

# Query for violations
./target/release/patch-prolog --query "violation(Field, Reason)"
# → {"solutions":[{"Field":"ssn","Reason":"sensitive_field"},{"Field":"password","Reason":"sensitive_field"}],"count":2,"exhausted":true}

# Exit code 1 = violations found
echo $?
# → 1

# Text output
./target/release/patch-prolog --query "violation(Field, Reason)" --format text
# Field = ssn
# Reason = sensitive_field
# Field = password
# Reason = sensitive_field

Example: Family Relationships

cp examples/family.pl knowledge/
cargo build --release

./target/release/patch-prolog --query "grandparent(tom, X)" --format text
# X = bob
# X = carol

Exit Codes

Code	Meaning
0	No solutions (compliant)
1	Solutions found (violations)
2	Parse error
3	Runtime error

Writing Rules

Place .pl files in knowledge/. They are compiled into the binary on cargo build — the binary has no runtime file dependencies.

The standard library (knowledge/stdlib.pl) is always included and provides: member/2, append/3, length/2, last/2, reverse/2, nth0/3, nth1/3.

Built-in Predicates

~55 built-in predicates covering core operations, type checking, control flow, arithmetic, I/O, term ordering, introspection, sorting, and number conversion. See docs/ARCHITECTURE.md for the full list.

Documentation

• docs/ARCHITECTURE.md — System structure, module responsibilities, data flows
• docs/TESTING.md — Test organization, running tests, writing tests
• docs/design/ — Design decisions and technical rationale
• ROADMAP.md — Completed phases and future work

Development

cargo test --all    # Run all 277 tests (134 unit + 143 integration)
cargo build         # Debug build
cargo run -- --query "true" --format text   # Quick smoke test

Architecture

Rust workspace with two crates:

• patch-prolog — CLI binary (src/main.rs, build.rs)
• patch-prolog-core — Engine library (crates/patch-prolog-core/) — tokenizer, parser, unifier, solver, built-ins

The engine compiles Prolog at build time via build.rs, serializes with bincode, and embeds the compiled database in the binary. At runtime, queries are parsed and resolved against the embedded knowledge base. See docs/ARCHITECTURE.md for details.