async.js

// fileIO style continuables example
// Note: All the three examples here are done based on the *same* API,
// namely the fileIO continuables API

// "Promise lite" style with either:
readFile("11.txt")(either(
function (e) {
  // handle an error
},
function (obj) {
  // handle a success
}));

// bentomas continuable style:
readFile("11.txt")(function (succeeded, obj) {
if (succeeded) {
  // handle success
} else {
  // handle error
});

// Pure continuable style, agnostic to number of outcomes:
readFile("11.txt")(function (x) {
if (x[0]) {
  // handle success
} else {
  // handle error
});