lisp parser

lispy.py

def read_from_tokens(tokens):
	token = tokens.pop(0)
	if token == '(':
		L = []
		while tokens[0] != ')':
			L.append(read_from_tokens(tokens))
		tokens.pop(0)
		return L
	elif token == ')':
		raise SyntaxError('unexpected )')
	else:
		return token


tk = str.split('( + 1 ( * ( - 10 9 ) 2 ) )', ' ')
print read_from_tokens(tk)