ReasonML inheritance interop

Base.bs.js

// Generated by BUCKLESCRIPT VERSION 3.1.5, PLEASE EDIT WITH CARE
'use strict';



class BaseModel {
    static findById() {
        return new this();
    }

    updateAttribute(k, v) {
        this[k] = v;
        return this;
    }

    toJSON() {
        return this;
    }
}

class Todo extends BaseModel {
    constructor(props) {
        let {title, completed} = props || {};
        super();
        this.title = title || "";
        this.completed = completed || false;
    }
}

let todo1 = Todo.findById().updateAttribute("title", "Done");
console.log('todo1', todo1);
  
;

var Instance = /* module */[];

var Model = /* module */[/* Instance */Instance];

var todo2 = Todo.findById(1).updateAttribute("title", "Done");

console.log("todo2", todo2);

console.log(todo2.toJSON().completed);

exports.Model = Model;
exports.todo2 = todo2;
/*  Not a pure module */

Base.re

%bs.raw
{|
class BaseModel {
    static findById() {
        return new this();
    }

    updateAttribute(k, v) {
        this[k] = v;
        return this;
    }

    toJSON() {
        return this;
    }
}

class Todo extends BaseModel {
    constructor(props) {
        let {title, completed} = props || {};
        super();
        this.title = title || "";
        this.completed = completed || false;
    }
}

let todo1 = Todo.findById().updateAttribute("title", "Done");
console.log('todo1', todo1);
  |};

module Model = {
  module Instance = {
    type t('a);
    [@bs.send.pipe: t('a)] external toJSON : unit => 'a = "toJSON";
    [@bs.send.pipe: t('a)]
    external updateAttribute : (string, 'b) => t('a) = "updateAttribute";
  };

  type t('a);
  [@bs.send.pipe: t('a)]
  external findById : int => Instance.t('a) = "findById";
};

type todoAttributes = {
  .
  "title": string,
  "completed": bool,
};

[@bs.val] external todoModel : Model.t(todoAttributes) = "Todo";

let todo2 =
  todoModel
  |> Model.findById(1)
  |> Model.Instance.updateAttribute("title", "Done");

Js.log2("todo2", todo2);

Js.log((todo2 |> Model.Instance.toJSON())##completed);