parser.js

var readtable = {
	"(": form,
	" ": space, "\t": space, "\n": space, "\r": space,
}
var white = " \t\n\r"
var atomEnd = " \t\n\r);"
var formEnd = ")"
var escape = "\\"
function parse(s) {
	s.marker = s.cursor
	return (readtable[s.ch] || atom)(s)
}
function next(s) {s.ch = s.code.charAt(++s.cursor)}
function token(s) {return s.code.slice(s.marker, s.cursor)}
function is(set, s) {return set.indexOf(s.ch) > -1}
function form(s) {
	var list = []
	next(s)
	while (!is(formEnd, s)) {
		var item = parse(s)
		if (item) list.push(item)
	}
	next(s)
	return list
}
function space(s) {
	next(s)
	while (is(white, s)) next(s)
}
function atom(s) {
	do {ch(s)} while (!is(atomEnd, s) && !(s.ch in readtable))
	return token(s)
}
function ch(s) {
	if (is(escape, s)) next(s)
	next(s)
}
function p(s) {
	return parse({cursor: 0, marker: 0, ch: "(", code: "(program " + s + ")"})
}

yeah maybe I should clean up the code and put it up in a repo when I get some time. I was mostly just toying w/ this code, but it's grown quite a bit since I posted this gist and it's not so toy-ish anymore.