array lenght by catamorhism

by dimitrs_papadimitriou

HTML

<script src="https://rawgit.com/eu81273/jsfiddle-console/master/console.js"></script>

JavaScript

Array.prototype.matchWith = function (pattern) {
           
        return this.length == 0 ?
            pattern.empty() :
            pattern.concat(this[0], this.slice(1));// informed decesion not to clone
    }
 

 Array.prototype.lenght1=function(){
   return this.matchWith({
        empty: () => 0,
        concat: (v, r) => 1 + r.lenght1()
    });
 } 
 var lenght = [1, 2, 3, 4, 5, 2].lenght1()
 console.log(lenght);