bs-most

BuckleScript bindings for Most.js.

In Reason:

let add x y => x + y;
let isEven x => x mod 2 === 0;

Most.(
  fromList [0,1,2,3,4,5,6,7,8]
  |> map (add 2)
  |> filter isEven
  |> observe (fun x => Js.log x)
  |> Js.Promise.then_ (fun _ => {
    Js.log "Stream completed";
    Js.Promise.resolve ()
  })
);

/**
 * Logs:
 * 2
 * 4
 * 6
 * 8
 * 10
 * Stream completed
 **/

How do I install it?

Inside of a BuckleScript project:

npm install --save bs-most

Then add bs-most to your bs-dependencies in bsconfig.json:

{
  ...
  "bs-dependencies": [
    "bs-most"
  ]
}

How do I use it?

The Most.js API docs are probably the best source of information about each method. This library attempts to provide very low-level bindings, except for what's noted in the What's different section.

The bindings are a single file in src/most.re. I try to provide comments next to each binding and am working on flushing out tests so that users can refer to them.

I am also available by e-mail or DM on the Reason discord (username: @lilactown).

What's missing

1. generate - Reason doesn't have generator support yet
2. transduce - Awkward to use in Reason/OCaml without a solid transducer impl (maybe coming soon?? 😉)
3. combineArray - the callback for this is variadic (depending on how many streams you have in the array), not sure how to type it yet 😞

What's different

1. Predicates that normally return "truthy" values, now only accept returning booleans
2. sample is variadic so we offer sample1, sample2, sample3... sample6
3. fromEvent - DOM events are supported, but generic EventEmitter's are not yet
4. from only works on arrays right now; generic iterators must be coerced
5. fromList is a function that creates a stream from a Reason List type, e.g. fromList([1, 2, 3])
6. unfold is modeled a bit differently - instead of taking in a JS object { done, value, seed }, it takes an option (value, seed). Example:

/* emits 2,4,6 then completes */
Most.unfold
  (
    fun seed =>
      if (seed < 4) {
        let nextSeed = seed + 1;
        Some (seed * 2, nextSeed)
      } else {
        None
      }
  )
  1;

Subjects

This library also includes some bindings for Subjects. Subjects are very useful for e.g. implementing a state store/dispatch system. The API is a little bit different from the raw most-subject library:

• Subject.make: creates an asynchronous Subject
• Subject.asStream: casts a subject to a stream, to be used by the rest of the Most module
• Subject.next: emits a value on a subject
• Subject.error: emits an error on a subject
• Subject.complete: completes a subject with no value
• Subject.completeWith: completes a subject with a value

Build

npm run build

Build + Watch

npm run watch

Testing

npm run test