Hysen Labsjunify
JUnify ― JavaScript Unification Library
Unification, in JavaScript
junify brings the unification algorithm to JavaScript for matching patterns against objects and arrays, with an API that reads like destructuring.
What unification means here
Unification is an algorithm for finding the substitutions that make two expressions match. If the expressions contain variables, those get bound to values so the match succeeds; if the expressions are not identical and the variables cannot be bound, it fails. The README compares the syntax and use case to destructuring assignment in JavaScript 1.7, and points out that extracting fields is only one use. Pattern matching and expert systems are listed as other things you could build.
The small API
All the code lives in the junify package, and the README notes the package name is left out of examples to keep them short. The important methods are unify, which takes two patterns and returns false or an object of variable bindings, and variable, which creates a named variable with an optional type. A wildcard constant matches any atom, array, or object without creating a binding, and there is a visit pattern method for traversing a pattern with a visitor object.
Matching both ways
Unification is bidirectional here. Both patterns can contain variables, so the example shows two patterns where bindings flow across both sides. A typed variable only matches when the types are identical in both patterns. That symmetry is what makes the library feel like real unification rather than a one directional matcher.
Where the limits are
The scope is explicit: junify can unify objects and arrays, not atoms. The atoms it refuses are Boolean, Number, String, Function, NaN, Infinity, undefined, and null. The wildcard constant can even stand in for an object property name, matching any property, but it must not be renamed because the library identifies wildcards internally by the symbol.
What you could build with it
Beyond extracting fields from JSON, the README points at pattern matching and expert systems, with a book reference for the classic example. The visit pattern method exists so you can rewrite custom pattern syntax before handing it to unify. For a library this small, the reach of those ideas is the interesting part.
Editorial conclusion
junify implements unification for objects and arrays in the browser and in Node.js. The API is small, unify and variable plus a wildcard constant and a pattern visitor, and the limits are clear: no atoms, and both patterns may carry variables.
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