Pipeline & compose functions

pipeline-and-compose.js

/* ES5 version */
function pipeline(seed) {
  var fns = [].slice.call(arguments, 1);
  
  return fns.reduce(function(result, fn) {
    return fn(result);
  }, seed);
}

function compose() {
  var fns = [].slice.call(arguments, 0);
  
  return function(seed) {
    return fns.reduceRight(function(val, fn) {
      return fn(val);
    }, seed); 
  }
}

/* ES6 version */
const pipeline = (seed, ...fns) => fns.reduce((result, fn) => fn(result), seed);
const compose = (...fns) => (seed) => pipeline.apply(seed, [seed, ...fns.reverse()]);

/* Pipelines examples */
console.log(pipeline()); // undefined
console.log(pipeline(42)); // 42
console.log(pipeline(42, n => -n)); // -42

/* Compose examples */
const greet = (name) => `hi: ${name}`;
const exclaim = (statement) => `${statement.toUpperCase()}!`;
const welcome = compose(greet, exclaim);
console.log(welcome('Yozh')); // 'hi: YOZH!'