@zireal/eslint-plugin-result-kit

Type-aware ESLint rules that enforce @zireal/result-kit's Result contract — the full-fidelity host of the must-use-result vocabulary. Closes the gap between Result in TypeScript and in Rust: a Result you produce but never handle should be an error, the way #[must_use] makes it one.

Install

pnpm add -D @zireal/eslint-plugin-result-kit

Peer dependencies (you almost certainly already have these): eslint >= 9, typescript >= 5, and @typescript-eslint/parser for type-aware linting.

Usage (flat config)

These rules are type-aware, so they need the TypeScript parser with type information enabled — exactly like any @typescript-eslint type-aware rule.

// eslint.config.js
import tseslint from "typescript-eslint";
import resultKit from "@zireal/eslint-plugin-result-kit";

export default tseslint.config({
  files: ["**/*.ts", "**/*.tsx"],
  languageOptions: {
    parser: tseslint.parser,
    parserOptions: { projectService: true }, // or: project: "./tsconfig.json"
  },
  plugins: { "@zireal/result-kit": resultKit },
  rules: {
    "@zireal/result-kit/must-use-result": "error",
    "@zireal/result-kit/no-throw-in-result-fn": "error",
  },
});

Or spread the bundled recommended config and add the type-aware parser options:

import tseslint from "typescript-eslint";
import resultKit from "@zireal/eslint-plugin-result-kit";

export default tseslint.config(
  resultKit.configs.recommended,
  { languageOptions: { parser: tseslint.parser, parserOptions: { projectService: true } } },
);

Rules

| Rule | Description | Fixable | |---|---|---| | must-use-result | A Result-returning expression whose value is dropped is an error. | ✅ (void) | | no-throw-in-result-fn | A function declared to return a Result should not throw. | — |

How detection works

Result is identified structurally (spec §2: { ok: true, value } | { ok: false, error }), never by where it was imported from — so a consumer's local type MyResult = Result<…> alias and a hand-rolled { ok, value } are both caught. must-use-result resolves the type through wrappers, aliases, and unions; carves out any (no false positives); and defers Promise<Result> to no-floating-promises. "Consumed" is emergent from the types — a terminal like unwrapOr / match returns a non-Result, so dropping it is fine; a transform like map / andThen returns another Result, so dropping it is flagged.

Related

• @zireal/oxlint-plugin-result-kit — the syntax-tier Oxlint port of must-use-result.
• @zireal/result-kit — the core library.

License

MIT © Ali Farooq