Exercise 07 - add closure

gistfile1.txt

function isPrime( num ) {
  // everything but 1 can be prime
  var prime = num != 1;
  for ( var i = 2; i < num; i++ ) {
    if ( num % i == 0 ) {
      prime = false;
      break;
    }
  }
  return prime;
}

var cachify = function (fn) {
  var cache = {};
  return ((function(fn, cache) { 
      return function (arg) { 
      if (arg in cache) { 
          console.info('cache hit');
          return cache[arg];
        } 
        return cache[arg] = fn(arg);
      };
    })(fn, cache));
};

var isPrime = cachify(isPrime);