Ramda chain usage

Question

From the documentation:

var duplicate = n => [n, n];
R.chain(duplicate, [1, 2, 3]); //=> [1, 1, 2, 2, 3, 3]
R.chain(R.append, R.head)([1, 2, 3]); //=&g         


        

Answer 1

Hope this helps

let R = require('ramda')

// using vanillajs
let append = (arr1) => (arr2) => arr2.concat(arr1)
let double = (arr1) => arr1.map( x => 2*x )

let chain = (f, g) => arr => {
   let yarr = g(arr)
   return f(yarr)(arr)
}

console.log(chain(
   append,
   double
)([10, 15, 20]))

//using Ramda
console.log(R.chain(append, double)([10, 15, 20]))