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02 — First Query

The second step in the Get started tutorial sequence. After this page you will have made your first interaction with the pr4xis engine, in your browser, with the same WASM build that runs in production.

This page assumes you have already completed 01 — Install.

dev-web is a workspace-provided dev script that builds the WASM bundle, watches crates/ for changes, and serves the chat surface locally with live reload. The interaction runs entirely in your browser tab — sandboxed, no local process to manage, exactly the same code path as the production pr4xis.dev demo.

dev-web

You will see something like:

Building WASM...
Starting pr4xis-web with live reload...
  /                — WASM chatbot
  /decks/technical — presentation
Watching crates/ for changes — WASM rebuilds automatically.

Open the URL it serves — dev-web prints the address and port on startup (currently http://localhost:4096). The page loads the English ontology (~107K WordNet concepts compiled into the WASM binary at build time) and gives you a chat input.

If you don’t have dev-web on your path, you are not in the dev shell. Run devenv shell first if you use Nix, or fall back to Option B below.

Try a few queries

is a cat a mammal
define telescope
is a guitar a string instrument

The system tokenizes each input, parses it through the Lambek pregroup grammar, looks up the entities in the WordNet taxonomy, and answers from the loaded category. The trace pane shows every step the engine took.

What you should expect

The chat surface is a working surface, not a polished product. Three classes of behavior you will see:

  1. Clean derivation. The query parses, the entities resolve, the taxonomy traversal answers. The trace shows every step.
  2. Honest “no” with a reason. The query parses, but the answer doesn’t follow from the loaded ontology. The system says so. This is correct behavior — pr4xis cannot make up answers that aren’t in its axioms.
  3. Grammar gap. The query doesn’t fit the current pregroup parser coverage. The system says so. This is a bug report — file an issue with the exact input.

The third case is the one we care most about closing. Pr4xis will get better the more grammar gaps users surface.

Option B: The CLI chatbot (no browser)

If you cannot use dev-web for any reason, the same engine ships as a CLI:

cargo run -p pr4xis-cli

This starts a chat loop in your terminal. It loads the English ontology from the WordNet XML you fetched in 01 — Install; if that file is missing it stops with a message pointing you at pr4xis update wordnet. With the data in place it runs the same engine on the same ontology and gives the same answers — it prints the response text for each query rather than the browser’s live trace pane. Useful for headless servers, CI debugging, or anywhere a browser isn’t available.

Option C: The hosted demo

If you don’t want to run anything locally at all, open pr4xis.dev. Same WASM build as Option A, hosted as a static site. Loads the English ontology at startup (a few seconds), then accepts the same queries.

Inspecting the trace

The browser surfaces (Options A and C) render a structured trace for each query. The trace is a sequence of PipelineTraceEntry records, one per pipeline stage:

  1. Tokenize — input → TypedToken[]
  2. Parse — tokens → Lambek pregroup reduction
  3. Interpret — parse tree → Montague semantic form
  4. Speech act classification — what kind of thing the user said
  5. Metacognition — which response strategy fits
  6. Entity lookup / taxonomy traversal / common ancestor / etc. — the actual reasoning
  7. Realization — semantic answer → human-readable text

When something goes wrong, the trace is where you look first. Every entry tells you which ontology produced it, which operation was performed, and whether it succeeded.

What you have now

  • A working interaction with the pr4xis engine
  • A sense of which queries land cleanly and which don’t
  • A way to see the full reasoning trace for any query

Next

Continue with 03 — First Ontology to write your own minimal ontology! block.

  • Document date: 2026-04-14