composing lazy evaluation functions

map.js

function* random(limit = 4) {
  let count = 0
  while(count < limit) {
      yield Math.random();
      count++;
  }
}

function* map(f, gen){
  let next;
  let result = gen.next();
  while(!result.done){
    next = yield f(result.value)
    result = gen.next();
  }
  return result.value
}

const toFixed = n => +n.toFixed(2);
const add1 = n => +n + 1;
const log = console.log.bind(console);

// const x = map(log, map(toFixed, map(add1, random())));
// [...x];

//const compose = (...f) => seed => f.reduce((gx, fn) => (map(fn, gx)), seed);

// const x = compose(add1, toFixed);
// console.log([...x(random(4))]);

// const pipe = (...f) => seed => f.reduceRight((gx, fn) => (map(fn, gx)), seed)

// const x = pipe(toFixed, add1);
// console.log([...x(random(4))]);

function* reduce(gen, f) {
  let next;
  let result = gen.next();
  while(!result.done){
    next = yield f(result.value)
    result = gen.next();
  }
  return result.value
}

const compose = (...f) => seed => f.reduce(reduce, seed);
const pipe = (...f) => seed => f.reduceRight(reduce, seed);
console.log([...x(random(4))]);