ramda- 函数式编程库

npm install ramda

import * as R from 'ramda'

R.and(true, true); //=> true
R.and(true, false); //=> false
R.and(false, true); //=> false
R.and(false, false); //=> false

R.append('tests', ['write', 'more']); //=> ['write', 'more', 'tests']
R.append('tests', []); //=> ['tests']
R.append(['tests'], ['write', 'more']); //=> ['write', 'more', ['tests']]

const nums = [1, 2, 3, -99, 42, 6, 7];
R.apply(Math.max, nums); //=> 42

由返回值可与 < 和 > 比较的函数，创建一个升序比较函数
const byAge = R.ascend(R.prop('age'));
const people = [
  { name: 'Emma', age: 70 },
  { name: 'Peter', age: 78 },
  { name: 'Mikhail', age: 62 },
];
const peopleByYoungestFirst = R.sort(byAge, people);
  //=> [{ name: 'Mikhail', age: 62 },{ name: 'Emma', age: 70 }, { name: 'Peter', age: 78 }]

由首个参数是否小于第二个参数的判断函数，生成一个比较函数
const byAge = R.comparator((a, b) => a.age < b.age);
const people = [
  { name: 'Emma', age: 70 },
  { name: 'Peter', age: 78 },
  { name: 'Mikhail', age: 62 },
];
const peopleByIncreasingAge = R.sort(byAge, people);
  //=> [{ name: 'Mikhail', age: 62 },{ name: 'Emma', age: 70 }, { name: 'Peter', age: 78 }]

R.concat('ABC', 'DEF'); // 'ABCDEF'
R.concat([4, 5, 6], [1, 2, 3]); //=> [4, 5, 6, 1, 2, 3]
R.concat([], []); //=> []

由返回值可与 < 和 > 比较的函数，创建一个降序比较函数。
const byAge = R.descend(R.prop('age'));
const people = [
  { name: 'Emma', age: 70 },
  { name: 'Peter', age: 78 },
  { name: 'Mikhail', age: 62 },
];
const peopleByOldestFirst = R.sort(byAge, people);
  //=> [{ name: 'Peter', age: 78 }, { name: 'Emma', age: 70 }, { name: 'Mikhail', age: 62 }]

求差集。求第一个列表中，未包含在第二个列表中的任一元素的集合。对象和数组比较数值相等，而非引用相等。
R.difference([1,2,3,4], [7,6,5,4,3]); //=> [1,2]
R.difference([7,6,5,4,3], [1,2,3,4]); //=> [7,6,5]
R.difference([{a: 1}, {b: 2}], [{a: 1}, {c: 3}]) //=> [{b: 2}]

删除对象中指定 prop 属性。
R.dissoc('b', {a: 1, b: 2, c: 3}); //=> {a: 1, c: 3}

两数相除。等价于 a / b
R.divide(71, 100); //=> 0.71

const half = R.divide(R.__, 2);
half(42); //=> 21

const reciprocal = R.divide(1);
reciprocal(4);   //=> 0.25

R.includes(3, [1, 2, 3]); //=> true
R.includes(4, [1, 2, 3]); //=> false
R.includes({ name: 'Fred' }, [{ name: 'Fred' }]); //=> true
R.includes([42], [[42]]); //=> true
R.includes('ba', 'banana'); //=>true

R.indexOf(3, [1,2,3,4]); //=> 2
R.indexOf(10, [1,2,3,4]); //=> -1

R.innerJoin(
  (record, id) => record.id === id,
  [{id: 824, name: 'Richie Furay'},
   {id: 956, name: 'Dewey Martin'},
   {id: 313, name: 'Bruce Palmer'},
   {id: 456, name: 'Stephen Stills'},
   {id: 177, name: 'Neil Young'}],
  [177, 456, 999]
);
//=> [{id: 456, name: 'Stephen Stills'}, {id: 177, name: 'Neil Young'}]