# -*- Mode: Python; tab-width: 4 -*-

import string
import sys

class lisp_reader:

    # input buffering

    def __init__ (self, socket):
        self.socket = socket
        self.buffer = ''
        self.pos = 0

    def refill (self):
        self.buffer = self.socket.recv (8192)
        if not self.buffer:
            raise EOFError
        else:
            self.pos = 0

    def read_exact (self, size):
        left = len(self.buffer) - self.pos
        if size < left:
            result = self.buffer[self.pos:self.pos+size]
            self.pos += size
            return result
        else:
            result = self.buffer[self.pos:] + self.socket.recv_exact (size - left)
            self.buffer = ''
            self.pos = 0
            return result

    def peek (self):
        if (not self.buffer) or (self.pos >= len(self.buffer)):
            self.refill()
        return self.buffer[self.pos]

    def next (self):
        if (not self.buffer) or (self.pos >= len(self.buffer)):
            self.refill()
        self.pos += 1
        return self.buffer[self.pos - 1]

    # form reader

    def skip_whitespace (self):
        while 1:
            ch = self.peek()
            if not ch:
                break
            elif ch not in string.whitespace:
                # comments?
                if ch == ';':
                    while self.next() not in '\r\n':
                        pass
                else:
                    break
            else:
                self.next()

    def read (self):
        self.skip_whitespace()
        ch = self.peek()
        if ch == '':
            raise EOFError, "Unexpected end of file"
        elif ch == '(':
            return self.read_list()
        elif ch == '"':
            return self.read_string()
        elif ch == "'":
            self.next()
            return [('symbol', 'quote'), self.read()]
        elif ch in '-0123456789':
            a = self.read_atom()
            if a == '-':
                # bad, bad, bad
                return ('symbol', '-')
            all_digits = 1
            for ch in a:
                if ch not in '-0123456789':
                    all_digits = 0
                    break
            if all_digits:
                return int (a)
            else:
                return ('atom', a)
        elif ch == '\r':
            if self.read() != '\n':
                raise "Syntax Error"
            else:
                return
        else:
            atom = self.read_atom()
            if atom == 'NIL':
                return ('nil')
            else:
                return ('atom', atom)

    def read_atom (self):
        # read at least one character
        result = self.next()
        while 1:
            ch = self.peek()
            if ch in string.whitespace or ch in '()':
                return result
            else:
                result = result + self.next()

    def read_string (self):
        result = ''
        # thow away the quote.
        ch = self.next()
        while 1:
            ch = self.peek()
            if ch == '"':
                # throw away the close-quote
                ch = self.next()
                return ('string', result)
            else:
                result = result + self.next()

    def read_list (self):
        result = []
        # throw away the paren
        paren = self.next()
        while 1:
            self.skip_whitespace()
            p = self.peek()
            if p == ')':
                # throw away the paren
                ch = self.next()
                return result
            else:
                x = self.read ()
                result.append(x)

    def read_all (self):
        forms = []
        try:
            while 1:
                form = self.read()
                forms.append (form)
        except EOFError:
            return forms

if __name__ == '__main__':
    import pprint
    import sys

    if len (sys.argv) < 2:
        file = sys.stdin
    else:
        file = open (sys.argv[1], 'r')

    p = reader (file)
    pprint.pprint (p.read_all())