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ClojureScript Unraveled

1. 关于此书

本书涵盖了 ClojureScript 编程语言，可作为其开发工具的详细指南，并提供了一系列适用于 ClojureScript 日常编程的主题文章。

这不是一本入门编程的书，它假定读者至少有一种语言的编程经验。不过，并不要求有 Clojure 或者函数式编程经验。当谈到一些不是人尽皆知的 ClojureScript 理论基础时，我们会尝试给出参考材料的链接。

ClojureScript 文档虽很好但太过松散，因此我们想写一个参考资料的纲要，并提供全面的示例，作为 ClojureScript 的入门书和实用指南。本文档作为语言特性的参考和实战的手册，会随着 ClojureScript 语言更新。

本书将非常适合你，如果：

DadgadCafe

;;;;;;;;;; Last Element
;; (= (__ [1 2 3 4 5]) 5)
;; (= (__ '(5 4 3)) 3)
;; (= (__ ["b" "c" "d"]) "d")

#(nth % (- (count %) 1))
#(nth % (dec (count %)))

;;;;;;;;;; Penultimate Element
;; (= (__ (list 1 2 3 4 5)) 4)

DadgadCafe

// must return or await next() in koa2, otherwise promise chain will be terminated.

const delay = () => new Promise(resolve => {
    console.log('delay...')

    setTimeout(() => {
      resolve()
    }, 1000)
  })

DadgadCafe

const obj = {
  x: 10,
  foo: function foo () {
    function bar () {
      console.log(x) // undefined, scope foo
      console.log(y) // 30, scope bar
      console.log(this.x) // 20
      console.log(this.y) // undefined
    }

DadgadCafe

function proxied (obj) {
  const o = Object.assign({}, obj)

  function filterPrivate (key) {
    if (key[0] === '_') {
      throw Error('cannot access private key: ${key}')
    }
  }

  const handler = {

DadgadCafe

;; detailed continuation usage, see previous gist: https://gist.github.com/DadgadCafe/07b0b50bf9537522fed09b3dc8df2784

(define call/cc call-with-current-continuation)

(let* ((yin
         ((lambda (cc) (display #\@) cc)
          (call/cc (lambda (c) c))))
       (yang
         ((lambda (cc) (display #\*) cc)
          (call/cc (lambda (c) c)))))

DadgadCafe

(function () {
  setImmediate(function () {
    console.log(6) // run macro-task
  })

  setTimeout(function () {
    console.log(8) // 4ms delay
  }, 0)

  Promise

DadgadCafe

'use strict'

const isObject = obj => typeof obj === 'object'
const hasKey = (obj, key) => key in obj

const Undefined = new Proxy({},{
  get (target, key, receiver) {
    //  always return Undefined when accessing Undefined.whatever
    return receiver
  }

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function fakeGen (fromV = 0, toV, step = 1) {
  // only one arg
  if (toV == undefined) {
    toV = fromV
    fromV = 0
  }

  // init status
  const status = {
    done: false,

DadgadCafe

const fakeAjax = (time, cb) => {
  setTimeout(() => {cb('data...')}, time)
}

const noopPromise = new Promise(() => {})

// cancel promise when timeout reached, using Promise.race
const timer = (fn, time) =>
  Promise
    .race([