bs-result

Monadic interface for Belt.Result

This implementation is inspired by JavaScript Fantasy Land and closely follows the Funfix.org Either implementation.

Installation

1. Install the bs-result package.

yarn add bs-result

2. Add bs-result to your bsconfig.json

{
  "dependencies": [
    "bs-result"
  ]
}

Usage

Basic

let r =
  Result.return(20)
  |> Result.map(x => x + 20)
  |> Result.flatMap(x => Result.return(x + 2))
  |> Result.getOrElse(-1);
Js.log2("Result: ", r);

Integrations

Belt.Result

let r =
  Belt.Result.Ok(x => x + 10)
  |> Result.ap(Result.return(20))
  |> Belt.Result.map(_, x => x + 10)
  |> Result.flatMap(x => Belt.Result.Ok(x + 2))
  |> Belt.Result.getWithDefault(_, -1);
Js.log2("Result: ", r);

Js.Promise

  Js.Promise.resolve(20)
  |> Js.Promise.then_(x => Result.Promise.return(x))
  |> Result.Promise.flatMap(x => Result.return(x + 10))
  |> Result.Promise.map(x => x + 10)
  |> Result.Promise.andThen(x =>
       x + 2 |> Result.return |> Js.Promise.resolve
     )
  |> Result.Promise.unsafeResolve
  |> Js.Promise.then_(result => {
       Js.log2("Result: ", result);
       Js.Promise.resolve();
     })

Full API Docs

TODO

• Integration with reason-future.
• Comonad implementation - functions are mis-named.