Playground

Type Datalog facts and rules below and hit Run. The program is evaluated entirely in your browser by the real C engine, compiled to WebAssembly — no server, no filesystem. The goal relation’s tuples are streamed back as plain text.

Output

(no results)

Supported subset

The in-browser engine supports the in-memory feature set of the language:

• Facts — bare lowercase symbols, double-quoted strings, integers, and flat list literals (elements are single values; nested lists aren’t yet accepted in a fact).
• Rules — including recursion (semi-naive fixpoint), stratified negation (!q(X)), and conjunctions.
• Aggregates — count(), sum(), min(), max().
• Equality & comparisons — =, < <= > >= !=.
• Arithmetic — + - * / %.
• Strings — concat, length, lower, upper, prefix, suffix, contains.
• Lists — cons, car, cdr, append, member, [X|Xs] patterns.
• Range predicate — range(X, Rel, Lo, Hi).
• Regex pattern walks — the ~ '...' form.

Not supported in the browser: publish/snapshot, time-travel (as-of) queries, variadic relations, and the WAL / incremental-maintenance API — all of which require the disk-backed engine.

Rendering caveat: the engine uses the CLI’s value heuristic, so a raw integer result (including one inside a list literal) that happens to equal a small symbol id can display as that symbol instead of the number. This is the documented B6 int-vs-symbol collision — a display heuristic, not a bug. Examples above use integer data to stay unambiguous.

The WebAssembly bundle is rebuilt from the C source with make wasm; see docs/README for details.