fluture/src/map-rej.js

FantasyLand compliant (monadic) alternative to Promises

import {call} from './internal/utils.js';
import {createTransformation, Reject, application1, application, future, func} from './future.js';

export var MapRejTransformation = createTransformation(1, 'mapRej', {
  rejected: function MapRejTransformation$rejected(x){
    return new Reject(this.context, call(this.$1, x));
  }
});

export function mapRej(f){
  var context1 = application1(mapRej, func, arguments);
  return function mapRej(m){
    var context2 = application(2, mapRej, future, arguments, context1);
    return m._transform(new MapRejTransformation(context2, f));
  };
}