add-unifier

name	add-unifier
description	Add a new unifier module to deep6. Use when asked to create custom pattern matching logic or extend unification behavior.

Add a New Unifier

Create a new unifier that extends deep6's pattern matching capabilities.

Steps

1. Create the unifier file at src/unifiers/foo.js:

   • Import Unifier from ../env.js
   • Create a class extending Unifier
   • Implement the unify(val, ls, rs, env) method
   • Export a factory function and the class

2. Example structure:

   import {Unifier, isVariable} from '../env.js';
   
   class MyUnifier extends Unifier {
     constructor(options) {
       super();
       this.options = options;
     }
   
     unify(val, ls, rs, env) {
       // Return true for match, false for failure
       // Push to ls/rs to continue unification with sub-values
       if (isVariable(val)) return false;
       // Your matching logic here
       return true;
     }
   }
   
   const myUnifier = options => new MyUnifier(options);
   
   export {MyUnifier};
   export default myUnifier;
   

3. Add tests in tests/tests.js:

   • Import the unifier: import myUnifier from '../src/unifiers/myUnifier.js';
   • Test matching success cases
   • Test matching failure cases
   • Test with variables and wildcards

4. Run tests: npm test

5. Create wiki documentation at wiki/myUnifier.md:

   • Description and use cases
   • API reference
   • Usage examples

6. Update wiki/Home.md — Add link under Unifiers section

7. Update ARCHITECTURE.md:

   • Add to project layout tree
   • Add to dependency graph
   • Add to unifier list

8. Update llms.txt and llms-full.txt:

   • Add unifier to API reference
   • Include example usage

9. Verify: npm test

Unifier Conventions

• Class name: PascalCase (e.g., MatchString, MyUnifier)
• Factory function: camelCase (e.g., matchString, myUnifier)
• File name: camelCase (e.g., matchString.js, myUnifier.js)
• Extend Unifier class from env.js
• Implement unify(val, ls, rs, env) method
• Return true for success, false for failure
• Use ls.push() and rs.push() to queue sub-value comparisons
• Check for isVariable(val) if variables should not match directly

Key Patterns

Simple predicate

unify(val, ls, rs, env) {
  return typeof val === 'number' && val > 0;
}

Capture values

unify(val, ls, rs, env) {
  ls.push(this.capture);
  rs.push(val);
  return true;
}

Delegate to unification

unify(val, ls, rs, env) {
  ls.push(this.pattern);
  rs.push(val);
  return true; // Continue unification with pushed values
}

See Also

• Existing unifiers: src/unifiers/
• Unifier base class: src/env.js
• Unification algorithm: src/unify.js