stream head tail

stream.js

function node(head, tail) {
    return [head, tail];
};
 
function head(stream) {
    return stream[0];
};
 
function tail(stream) {
    var tail = stream[stream.length - 1];
    return (tail instanceof Function) ? tail() : tail;
};
 
function drop(stream) {
    var h = head(stream);
    var t = tail(stream);
    stream[0] = t ? t[0] : null;
    stream[1] = t ? t[1] : null;
    return h;
};
 
function iterate(stream, callback, limit) {
    while (head(stream) && ((undefined == limit) || (limit > 0))) {
        limit && limit--;
        callback(drop(stream));
    };
};
 
function show(stream, limit) {
    iterate(stream, function (x) {
        console.log(x);
    }, limit);
};
 
//Examples
function upto(from, to) {
    return (from > to) ? null : node(from, function() {
        return upto(from + 1, to);
    });
};
function upfrom(start) {
    return node(start, function() {
        return upfrom(start + 1);
    });
};
 
console.log("upto:");
show(upto(3, 6));
 
console.log("upfrom:");
show(upfrom(7), 10);