@greffon/eslint-plugin

The lint surface of Greffon, expression trees for TypeScript: ESLint rules that enforce the expression-lambda subset, in ESLint and in oxlint.

One validator backs three hosts: the rules share @greffon/capture's subset checks with the build transform and @greffon/ts-plugin, so an invalid lambda gets the same Rxxxx code and span as a squiggle, a lint finding, and a build error.

Install

npm install -D @greffon/eslint-plugin

Usage

In ESLint, use the flat-config preset (the peer dependency is eslint >=8):

import greffon from "@greffon/eslint-plugin";

export default [greffon.configs.recommended];

oxlint loads ESLint plugins too, through jsPlugins (alpha, not semver-guarded). Greffon's own .oxlintrc.json:

{
  "jsPlugins": [{ "name": "greffon", "specifier": "@greffon/eslint-plugin" }],
  "rules": {
    "greffon/valid-expression": "error",
    "greffon/no-opaque-callback": "warn"
  }
}

Rules

• greffon/valid-expression (error in recommended): rejects out-of-subset syntax with the shared codes, and autofixes ==/!= to ===/!== (R1103).
• greffon/no-opaque-callback (warn in recommended): flags a function passed by reference where a provider would need a tree (R2003), the lint-time face of the boundary rule.

The rules run without type information. They check expr() calls and query calls whose receiver roots at a createContext() result from @greffon/query, traced within one file. A context imported from another module is not checked at lint time; the build transform and the editor plugin resolve receivers across modules and catch it.

Docs

• Editor & lint
• Error reference

License

MIT