이터러블 중심 프로그래밍 실무 코드

var users=[
  {name:'a', age:21, family:[
    {name:'a1', age:53}, {name:'a2', age:47},
    {name:'a3', age:16}, {name:'a4', age:15}
    ]},
  {name:'b', age:24, family:[
    {name:'b1', age:58}, {name:'b2', age:51},
    {name:'b3', age:19}, {name:'b4', age:22}
    ]},
  {name:'c', age:31, family:[
    {name:'c1', age:64}, {name:'c2', age:62}
    ]},
  {name:'d', age:20, family:[
    {name:'d1', age:42}, {name:'d2', age:42},
    {name:"d3", age:11}, {name:'d4', age:7}
    ]}
  ];

go(users,
   L.map(u=>u.family),
   L.flatten,
   takeAll,
   log);
// 0: {name:"a1",age:53}...13: {name:"d4",age:7}

go(users,
   L.map(u=>u.family),
   L.flatten,
   L.filter(u=>u.age<20),
   L.map(u=>u.name)
   take(4),
  log);
// (4) ["a3","a4","b3","d3"]

go(users,
   L.map(u=>u.family),
   L.flatten,
   L.filter(u=>u.age<20),
   L.map(u=>u.age),
   take(3),
   reduce(add),
  log);        // 50