eslint-plugin-functional

ESLint plugin enforcing functional programming patterns in JavaScript and TypeScript, v9.0.4 (Feb 2026). Requires ESLint ^9.0.0 or ^10.0.0 and TypeScript >=4.7.4. Actively maintained with monthly releases. Provides presets (strict, recommended, lite) and categorized rulesets for immutability, no statements, no exceptions, currying, and stylistic rules. Differentiated by TypeScript-first design, type-aware rules (e.g., type-declaration-immutability), and support for Map/Set mutation detection. Recommended alternative to plugins like eslint-plugin-immutable or writing custom rules.