monad.js

function MONAD(modifier) {
  const prototype = Object.create(null);

  function unit(value) {
    const monad = Object.create(prototype);
    monad.bind = function(f, ...args) {
      return f(value, ...args);
    };
    if (typeof modifier === 'function') {
      modifier(monad, value);
    }
    return monad;
  };

  unit.lift = function (name, func) {
    prototype[name] = function (...args) {
      return unit(this.bind(func, args));
    };
    return unit;
  }
  
  return unit;
}

var ajax = MONAD().lift('alert', alert);
var monad = ajax('Hello world.');
monad.alert();

const maybe = MONAD(function (monad, value) {
  if (value === null || value === undefined) {
    monad.is_null = true;
    monad.bind = function() {
      return monad;
    }
  }
});

var monad = maybe(null);
monad.bind(alert);