We can compose lenses to get value: const addrs = [{street: '99 Walnut Dr.', zip: '04821'}, {street: '2321 Crane Way', zip: '08082'}] const user = {id: 3, name: 'Charles Bronson', addresses: addrs} const addresses = R.lensProp('addresses') const stre…

Curry: The idea of Curry is to spreate the data from the function. Using Curry to define the function logic and later pass the data into the function logic. Example1: const get = R.curry(function(prop, obj){ return obj[prop]; }); const obj1 = { foo:…

In this lesson, we'll refactor a React component to use Ramda lenses to update our component state. We'll create a lens to focus on the property we want to target and use over to apply the existing state value to a utility function and we'll get back…

In this lesson we'll take some existing code and refactor it using some functions from the Ramda library, most notably, compose and converge. When we're done, we'll have taken a function with a couple of local variables and parameter references and c…

In this lesson we'll learn the basics of using lenses in Ramda and see how they enable you to focus changes on specific properties of an object while keeping your data immutable. what 'R.lens' do is able to get or set prop value but keep the object i…

const log = function(x){ console.log(x); return x; } const get = R.curry(function(prop, obj){ return obj[prop]; }) var people = [ {name: "Wan"}, {name: "Zhentian"} ]; var res = R.compose( get('name'), log, R.head )(people); console.log…

const log = function(x){ console.log(x); return x; } const get = R.curry(function(prop, obj){ return obj[prop]; }) var people = [ {name: "Wan"}, {name: "Zhentian"} ]; var res = R.compose( get('name'), log, R.head )(people); console.log…

const curry = R.curry((fns, ary) => R.ap(fns, ary)); ), R.add()]); ,,]); console.log(res); //[2, 4, 6, 4, 5, 6] const compose = R.compose( R.reverse, R.ap([R.multiply(), R.add()]) ); ,,]); console.log(res1); //[6, 5, 4, 6, 4, 2] , x)) const pipe = R.…

函数式编程中有一种模式是通过组合多个函数的功能来实现一个组合函数.一般支持函数式编程的工具库都实现了这种模式,这种模式一般被称作compose与pipe.以函数式著称的Ramda工具库为例. const R = require('ramda'); function inc (num) { return ++num; } const fun1 = R.compose(Math.abs, inc, Math.pow) const fun2 = R.pipe(Math.pow, Math.abs, i…

学习函数式编程的过程中,我接触到了 Ramda.js. 我发现,这是一个很重要的库,提供了许多有用的方法,每个 JavaScript 程序员都应该掌握这个工具. 你可能会问,Underscore 和 Lodash 已经这么流行了,为什么还要学习好像雷同的 Ramda 呢? 回答是,前两者的参数位置不对,把处理的数据放到了第一个参数. var square = n => n * n; _.map([4, 8], square) // [16, 64] 上面代码中,_.map的第一个参数[4, 8]…