//Combinators
const I = x => x;

//Function composition
const compose = f => g => x => f(g(x));

//List manipulation
const head = xs => xs[0];
const tail = xs => xs.slice(1);
const append = x => xs => [...xs, x];

//Iteration
const foldl = f => y => xs => xs.length > 0 ? foldl(f)(f(y)(head(xs)))(tail(xs)) : y;
const foldr = f => y => xs => xs.length > 0 ? f(foldr(f)(y)(tail(xs)))(head(xs)) : y;
const map = f => foldl(y => x => append(f(x))(y))([]);

//Lib
const add = a => b => a + b;
const mult = a => b => a * b;
const pipe = foldr(compose)(I);

//Program
map(pipe([add(1), mult(2)]))([1, 2, 3]);