Question

I am programming a Lisp like language on JavaScript for learning purposes. Every object is part of a tree so it must keep track of its parent. The only problems are numbers and strings:

foo = {};
var a = 1;
a.parent = foo;

This will not work. I have to do this instead:

foo = {};
var a = {type:'number',value:1,parent:foo}

So I would have to box every number and string on my language in a hash like that. I pretend to do some extensive matrix math on said language, so I am worried. Would this approach be a hit on performance?

Answer 1

As Reid suggested:

function number(n){
    return {type:'number',parent:undefined,value:n};
}
function sum(a,b){
    return {type:'number',parent:undefined,value:a.value+b.value};
}
var i = number(0);
for (var t=Date.now(); Date.now()-t < 1000;){
    var i=sum(i,number(1));}
console.log('Operations with boxing: ',i.value);
var i = 0;
for (var t=Date.now(); Date.now()-t < 1000;){
    var i=i+1;}
console.log('Operations without boxing: ',i);

Output:

Operations with boxing: 1911258
Operations without boxing: 16805783

This probably answers the question. I wonder if there is an alternative that won’t be such a performance hit.