djfm

const scale = {
    c: 0,
    'c#': 1,
    d: 2,
    'd#': 3,
    e: 4,
    f: 5,
    'f#': 6,
    g: 7,
    'g#': 8,

djfm

const {
  Cluster,
  N1qlQuery,
  MutationState,
} = require('couchbase');

const URL = require('url');

const addQueryParams = params => url => {
  const parsed = URL.parse(url);

djfm

const just = x => Promise.resolve(x);
const nothing = () => Promise.reject();

chain(
  () => just(1),
  () => nothing(),
  (_, x, y) => just(x / y)
)()
 .should.be.rejected;
 

djfm

const chainStep = fn => (argSource, history) => {
  if (argSource && (typeof argSource === 'object')) {
    const then = argSource.then;
    if (typeof then === 'function') {
      return Promise.all(history).then(
        settledHistory =>
          then.call(argSource, arg => fn(arg, ...settledHistory))
      );
    }
  }

djfm

do
  a <- makeId "dress"
  b <- makeId "dress"
  c <- makeId "dress"
  return checkOrdered a b c

djfm

storage.makeId('dress')
.then(
  a =>
    storage.makeId('dress')
    .then(
      b =>
        storage.makeId('dress')
        .then(
          c => {
            a.should.be.lessThan(b);

djfm

chain(
  () => storage.makeId('dress'),
  () => storage.makeId('dress'),
  () => storage.makeId('dress'),
  (_, a, b, c) => {
    a.should.be.lessThan(b);
    a.should.be.lessThan(c);
    b.should.be.lessThan(c);
  }
)()

djfm

const chain = (...fns) =>
  initialValue => fns.reduce(
    (result, fn) => {
      if (result && (typeof result === 'object')) {
        const then = result.then;
        if (typeof then === 'function') {
          return then.call(result, fn);
        }
      }
      return fn(result);

djfm

const chain = (...fns) => initialValue =>
  fns.reduce((previousOutput, fn) => fn(previousOutput), initialValue);
  
chain(x => x + 1, x => x / 2)(0).should.equal(0.5);
chain(x => x / 2, x => x + 1)(0).should.equal(1);

// run it: https://jsfiddle.net/s8hwae47/

djfm

const chai = require('chai');
chai.should();

const listMonad = {
  // make :: a -> m a
  // make :: a -> [a]
  make: (...args) => args,
  // bind :: m a -> (a -> m b) -> m b
  // bind :: [a] -> (a -> [b]) -> [b]
  bind: someList => listReturningFunction =>