rubico

🏞 a shallow river in northeastern Italy, just south of Ravenna

functional programming for humans

Why?

well you can, and rubico can help you do it. And no, you do not need to know what a monad is.

Okay, show me some stuff

rubico's flow executes functions specified in its arguments sequentially,
plugging in the return value from one function directly into the next function
regardless of whether the function returns a promise.

Let's get some json data with just functions.

flow(
  fetch,
  response => response.json(),
  console.log,
)('https://jsonplaceholder.typicode.com/todos/1')
// > { userId: 1, id: 1, title: 'delectus aut autem', completed: false }

The above block executes fetch, response => response.json(), and console.log
in sequence. The url 'https://jsonplaceholder.typicode.com/todos/1' is passed to
fetch, the return value of which is passed to response => response.json(),
and so forth. it is the more expressive version of

void (async (url) => {
  const response = await fetch(url)
  const data = await response.json()
  console.log(data)
})('https://jsonplaceholder.typicode.com/todos/1')
// > { userId: 1, id: 1, title: 'delectus aut autem', completed: false }

Chaining functions is cool, but you don't need a whole library to do that.

Let's make a post request. This time, rubico is namespaced to _.

// url (string) => body (object) => response (object)
const makePostRequest = url => _.flow(
  JSON.stringify, // (5)
  _.diverge([ // (6)
    url,
    _.diverge({
      method: 'POST',
      body: _.id,
      headers: {
        "Content-type": "application/json; charset=UTF-8",
      },
    }),
  ]),
  _.spread(fetch), // (7)
  response => response.json(), // (8)
)

const postToHttpBin = makePostRequest('https://httpbin.org/post') // (4)

_.flow(
  postToHttpBin, // (1)
  _.get('json'), // (2)
  console.log, // (3)
)({ a: 1 })

What's going on at a high level:
(1) make a post request with body { a: 1 } to http bin
(2) get the json prop of that response
(3) log that value out to the console

What's going on in postToHttpBin:
(4) partially apply 'https://httpbin.org/post' to makePostRequest,
a higher order function that takes a url

What's going on in makePostRequest after applying url:
(5) json stringify the input body
(6) create a structure with stringified body that resembles [url, { method, body, headers }]
(7) spread that structure as arguments into fetch
(8) format the response payload

The powerful idea here is functions as modules; that you can solve a problem once,
name it something you can remember, and use it anywhere you see fit.

That's the gist of it. For more examples, see the examples folder.
For the full documentation, please visit rubico.land