one-thing-functions

Strict function-design checker CLI.

Rules default to FP-first domain records:

• one function does one thing
• max one argument
• max 25 lines by default
• no currying tricks
• no array packs
• no object bags outside boundary/factory records

Setup

npx one-thing-functions init
npm install -D one-thing-functions
npm run lint:functions:audit

init detects common roots (src, lib, app, scripts, packages, etc.). If none exist, it falls back to .. lint:functions:audit is advisory and exits successfully after reporting findings. Use lint:functions when ready for CI enforcement.

Custom roots:

npx one-thing-functions init --roots=src,scripts

CLI

npx one-thing-functions check src --advisory
npx one-thing-functions check src
npx one-thing-functions check src --profile=legacy-migration
npx one-thing-functions check src --config=one-thing-functions.config.mjs

Config

export default {
  profile: "fp-first",
  roots: ["src"],
  maxLines: 25,
  utilityAllowlist: ["clamp"],
};

Profiles:

• fp-first default
• oo-friendly
• legacy-migration

Agent skill

The skill lives once at repo root:

../../skills/engineering/one-thing-function/SKILL.md

Install it with the open skills CLI:

npx skills add <owner>/arc-forge --skill one-thing-function