lazy_tail_call.js

// Attempt to do tail-recursion in JavaScript without getting a stack-overflow exception. 
// This is horribly slow because of all of the extra stack frames pr. thunk.
// What would you call this? Lazy-tail-recursion? 

var tailrec = function(f) {
    for(var x = f() ; typeof x == "function" ; x = x()){}
    return x;
};

var counter = function(){
    var counter_tail = function(cnt){
        if (cnt === 100000) {
            return cnt;
        } else {
            return function(){ return counter_tail(cnt+1); };
        }
    };
    return tailrec(function(){ return counter_tail(0); });
};

console.log(counter());