Javascript placeholder currying

gistfile1.js

var _ = {};

var placeholder = function(f /*, ...*/) {
    var bound = [].slice.call(arguments, 1);
    return function(/*...*/) {
        var indx = 0;
        return f.apply(f, [].reduce.call(arguments, function(p, c) {
            while (indx in bound) {
                var val = bound[indx];
                if (val === _)
                    break;
                p[indx] = val;
                ++indx;
            }
            p[indx] = c;
            ++indx;
            return p;
        }, bound.slice()));
    };
};