Lazy Lambda

lazy.js

'use strict';

var R = require('ramda');
var expensiveMap = R.compose(R.join(''), R.repeat(R.__, 10000));

var data = R.range(1, 10000);

// $ time node lazy.js
// node lazy.js  3.42s user 0.16s system 99% cpu 3.584 total
R.take(1, R.map(expensiveMap, data)); 

// $ time node lazy.js
// node sdfsdf.js  0.10s user 0.01s system 94% cpu 0.119 total
R.into([], R.compose(R.take(1), R.map(expensiveMap)), data);