Skip to main content

Concept Layers

Nudo is designed so you only learn what you need.

Day 0 — Zero concepts​

Write plain JavaScript. Run inference:

npx nudojs infer ./src/app.js

You get call-site cases: concrete inputs → inferred results. No annotations, no config.

Open the same file in VS Code with the Nudo extension for hover and inlays.

Default analysis mode: nudo.analysis.mode defaults to "exports". Files with export / sidecar / directives are analyzed by the IDE; set "all" for every target path or "directives" for the conservative gate. CLI infer on a named path still analyzes any target file.

Stop here if you only want types for existing JS.

Day 1 — Sidecar contracts​

When you need obligations (check gates in CI), add a sidecar next to the source:

// math.js
export function add2(x) {
  return x + 2;
}
// math.nudo.js
export const add2 = number().gt(0);
npx nudojs check ./src/math.js

Contracts come only from:

  • explicit sidecars (*.nudo.js) / @nudo:refine
  • call-site facts observed by the analyzer

No evidence → any/unknown. Nudo does not invent required slots from body AST scans.

Advanced — Abs​

The internal type is Abs (shape × term × pred × conf): types are computable values. nudo check --verbose shows the lossless Abs face. You rarely need this for day-to-day work.

Next​