lodash.js

function head (arr) { 
  var [start, ...rest] = arr; 
  return start;
}

function tail (arr) { 
  var [start, ...rest] = arr; 
  return rest;
}

function pick (object, keys) { 
  var returnObj = {}
  for(var i = 0;i<keys.length;i++) { 
    returnObj[keys[i]] = object[keys[i]]
  }
  return returnObj
}

function pipe (functions) { 
  return function (data) { 
    return functions.reduce(function (val, func) {
      return func(val)  
    }, data)
  }
}

const pipe = functions => data => functions.reduce((val, func) => func(val), data)