jhall

Like dhall, but with a language you already know

Are you tired of your config files developing their own domain specific languages?

Feel like your static, declarative configuration files could stand to be a little more dynamic?

Want to use functions to declare your data?

We can probably fix some of those.

Installation

npm install -g jhall

or with yarn,

yarn global add jhall

Usage

You now have the jhall binary on your path. Call it with the path to a CJS JavaScript file, and it will output your configuration to stdout.

You can optionally pass the -y flag to transform the output into YAML.

$ jhall config.js > config.json
# or
$ jhall -y config.js > config.yaml

Examples

DRY static config

const homeDir = userName => `/home/${username.toLowerCase()}`;
const users = ['Mark', 'Jet', 'Dave', 'Shay'];

module.exports = {
  users: users.map(u => ({homeDir: homeDir(u), name: u})),
};

Checking program arguments

module.exports = args => ({
  inYaml: args.yaml, // true/false
  flagB: args.b, // true/false
  optionX: args.x, // 'someValue'/undefined
  positionalArguments: args._, // ['arg1', 'arg2', 'arg3']
});

Asynchronous results

module.exports = async () => {
  const response = await fetchSomeData();

  return { remoteIp: response.data.requestIp };
};