small, pythonic lisp

Grab it here.

It's < 256 LOC toy lisp. Nothing super-fancy. If you don't count unit tests and Guido's mm.py it's even < 128 LOC.

It's quite pythonic. When you write eval in LISP it's just a big cond. It translates directly to if/elif/elif/... which doesn't look good. I used dict of functions instead, which looks better in my eyes. Uses as many Python features as possible. Python functions, python lists. etc.

Talking about Python and lisp lists:

class slist(object):
    class iterator(object):
        def __init__(self, lst):
            self.lst = lst
        def next(self):
            if self.lst:
                result = self.lst.car
                self.lst = self.lst.cdr
                return result
            else: raise StopIteration

    def __iter__(self):
        return slist.iterator(self)

    def __init__(self, a, b=None):
        self.car = a
        self.cdr = b

    def __str__(self):
        return '(%s)' % ' '.join(str(elem) for elem in self)

list_123 = slist(1, slist(2, slist(3)))
a, b, c = list_123

Yes, this is just a linked list, not a true scheme cons, since it doesn't support improper lists, I posted it just to show how Python iterators are neat.