babel-plugin-transform-pipeline

Compile pipeline operator (|>) to ES5

Proposal: mindeavor/es-pipeline-operator

---

Example

Basic

In

var user = { name: 'SuperPaintman' };

function capitalize(str) {
  return str.toUpperCase();
}

function sayHello(name) {
  return 'Hello, ' + name + '!';
}

var res = user.name
  |> capitalize
  |> sayHello;

// => "Hello, SUPERPAINTMAN!"

Out

var user = { name: 'SuperPaintman' };

function capitalize(str) {
  return str.toUpperCase();
}

function sayHello(name) {
  return 'Hello, ' + name + '!';
}

var res = sayHello(capitalize(user.name));

// => "Hello, SUPERPAINTMAN!"

With multi-argument functions

In

var user = { score: 40.49138 };

var res = user.score
  |> (_ => _ * 2)
  |> (_ => _.toFixed(2));

// => 80.98

Out

var user = { score: 40.49138 };

var res = (_ => _ * 2)((_ => _.toFixed(2))(user.score));

// => 80.98

Real use-case

var path = require('path');

var pathToUrl = (rootDir, filePath) => [rootDir, filePath]
  |> ((args) => path.relative(...args))
  |> path.dirname
  |> ((res) => res.split(path.sep).join(path.posix.sep))
  |> ((res) => '/' + (res === '.' ? '' : (res + '/')));

pathToUrl('./controllers', './controllers/api/users/index.js');
// => "/api/users/"

pathToUrl('./controllers', './controllers/index.js');
// => "/"

Out

var path = require('path');

var pathToUrl = (rootDir, filePath) => (res => '/' + (res === '.' ? '' : res + '/'))((res => res.split(path.sep).join(path.posix.sep))(path.dirname((args => path.relative(...args))([rootDir, filePath]))));

pathToUrl('./controllers', './controllers/api/users/index.js');
// => "/api/users/"

pathToUrl('./controllers', './controllers/index.js');
// => "/"

---

FAQ

Why do we need parentheses around multi-argument functions?

Because they separate the => from the |>.

Ie. the following code:

var res = user.score
  |> _ => _ * 2
  |> double;

Is equivalent to:

var res = user.score
  |> _ => _ * double(2);


// or


var secondArg = 2
  |> double;

var res = user.score
  |> _ => _ * secondArg;

Why |>?

Firstly, it is a invalid token in terms of javascript (ES3-ES2017).

Secondly, in vanilla javascript there are only 3 token starting with |: |, || and |=;

---

Installation

npm install --save-dev babel-plugin-transform-pipeline

# or

yarn add --dev babel-plugin-transform-pipeline

---

Usage

Via .babelrc (Recommended)

.babelrc

{
  "plugins": ["transform-pipeline"]
}

Via CLI

babel --plugins transform-pipeline script.js

Via Node API

require("babel-core").transform("code", {
  plugins: ["transform-pipeline"]
});

---

Build

npm run build

---

Test

npm run test

---

Contributing

1. Fork it (https://github.com/SuperPaintman/babel-plugin-transform-pipeline/fork)
2. Create your feature branch (git checkout -b feature/<feature_name>)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin feature/<feature_name>)
5. Create a new Pull Request

---

Contributors

• SuperPaintman SuperPaintman - creator, maintainer

---

License

MIT