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

// 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

;;;;;;;;;; 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

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

HASKELL PROGRAMMING FROM FIRST PRINCIPLES

CHAPTER1. ALL YOU NEED IS LAMBDA

1.1 All You Need is Lambda

lambda calculus:

computation model, 1930s, Alonzo Church, formalizing a method, Turing machines

DadgadCafe

-- lambda 
data Term = Lam Var Term
          | Var Var
          | App Term Term -- func application

data Var = V String

instance Show Var where
    show (V s) = s
    

DadgadCafe

I ii  iii  IV V   vi  vii'
i ii' IIIb iv v   VIb VIIb
  II7 III7    Vb7 VI7
  IIb

?: iib iiib vb vib viib vii VII

DadgadCafe

# naming conventions: 
# module_name, package_name, method_name, function_name, global_var_name, instance_var_name, function_parameter_name, local_var_name
# ClassName, ExceptionName
# GLOBAL_CONSTANT_NAME

*a = *range(3),  #(1, 2, 3)

#################
# http://sahandsaba.com/thirty-python-language-features-and-tricks-you-may-not-know.html

DadgadCafe

import signal

# broken in eventloop things
class Promise:
    def __init__(self, f):
        self.status = 'PENDING'
        self.cb = None
        f(self.__resolve)

    def resolve(v):

DadgadCafe

# http://sahandsaba.com/interview-question-groupon-probability.html
import random

def bernoulli_process(p):
    if p > 1.0 or p < 0.0:
        raise ValueError("p should be between 0.0 and 1.0.")
    while True:
        yield random.random() > p

def von_neumann_extractor(process):