How To Extend Js Class In Reasonml

For example, I have an es6-like class: class Foo {...} And I want to extend it: class Bar extends Foo {...} In reason-react documentation I found examples, but I'm not sure that it

Solution 1:

let foo bar => { ...baz, quux: ... } is not a syntax for inheritance, it's a syntax for composition. Specifically, it's taking the baz record value (not object) and updating its quux member (not method).

If you want to extend a JS class in Reason/BuckleScript, first keep in mind that BuckleScript generates code that's backwards-compatible with ES5, so that you don't need to use Babel. In fact BuckleScript doesn't directly support extending a class.

But, you can include raw JavaScript in your Reason source code using BuckleScript's [%%bs.raw] attribute ( https://bucklescript.github.io/bucklescript/Manual.html#_embedding_raw_js_code_as_statements ):

/* MyProject_Animal.re */

[%%bs.raw {|

// Dummy class for example:classAnimal {
  speak() {}
}

// or:// import Animal from "somewhere";classDogextendsAnimal {
  _name;

  constructor(name) {
    super();
    this._name = name;
  }

  speak() {
    console.log(`${this._name} says woof!!`);
    super.speak();
  }
}
|}];

And then you can write a binding to the Dog class in the code below that:

moduleAnimal_Dog = {
  type t;

  [@bs.new] external make: string => t = "Dog";
  /* Need this to ensure correct usage in other modules */let make = make;

  [@bs.send] external speak: t => unit = "";
};

let spot = Animal_Dog.make("Spot");
Animal_Dog.speak(spot);

But, remember that since this ES2015, you will need to run it through Babel if you want it to be backwards-compatible with pre-ES2015 browsers.