#SurviveJS 05 LT「forループを越えて」

beyond_for_loop.js

const double = x => x * 2;
const over5 = x => x > 5;

const a = [1, 2, 3].map(double).filter(over5);
console.log('********* a', a);

import * as R from 'ramda';

const times2Over5 = R.compose(
  R.tap(console.log),
  R.filter(over5),
  R.tap(console.log),
  R.map(double)
);

const b = times2Over5([1, 2, 3]);
console.log('********* b', b);

const c = times2Over5({ a: 1, b: 2, c: 3, str: 'string' });
console.log('********* c', c);

// error!
// const hoge = { a: 1, b: 2, c: 3 };
// hoge.map(x => x);

// error!
// const e = times2Over5(null);
// console.log('********* e', e);