A collection of ESLint rules for fp-ts

Assuming ESlint is installed locally in your project:

# npm
npm install --save-dev eslint-plugin-fp-ts

# yarn
yarn add --dev eslint-plugin-fp-ts

Then enable the plugin in your .eslintrc config

{
  "plugins": ["fp-ts"]
}

and enable the rules you want, for example

{
  "plugins": ["fp-ts"],
  "rules": {
    "fp-ts/no-lib-imports": "error"
  }
}

If you want to enable rules that require type information (see the table below), then you will also need to add some extra info:

module.exports = {
  plugins: ["fp-ts"],
  parserOptions: {
    tsconfigRootDir: __dirname,
    project: ["./tsconfig.json"],
  },
  rules: {
    "fp-ts/no-discarded-pure-expression": "error",
  },
};

If your project is a multi-package monorepo, you can follow the instructions here.

⚠️ Note that you will need to make the ESLint config file a .js file, due to the need of setting tsconfigRootDir to __dirname. This is necessary to make both editor integrations and the CLI work with the correct path. More info here: typescript-eslint/typescript-eslint#251

🔧 = auto-fixable via --fix (or via the appropriate editor configuration)

💡 = provides in-editor suggestions that need to be applied manually

The plugin defines a recommended configuration with some reasonable defaults.

To use it, add it to the extends clause of your .eslintrc file:

{
  "extends": ["plugin:fp-ts/recommended"]
}

The rules included in this configuration are:

• fp-ts/no-lib-imports
• fp-ts/no-pipeable

We also provide a recommended-requiring-type-checking which includes recommended rules which require type information.

This configuration needs to be included in addition to the recommended one:

{
  "extends": [
    "plugin:fp-ts/recommended",
    "plugin:fp-ts/recommended-requiring-type-checking"
  ]
}

👉 You can read more about linting with type information, including performance considerations here

The plugin also defines an all configuration which includes every available rule.

To use it, add it to the extends clause of your .eslintrc file:

{
  "extends": ["plugin:fp-ts/all"]
}