50 lines of code to achieve the snake of specific ideas and code

One of the little demos I've been preparing for interviews with recently, designed and implemented by myself in order to present myself, is to implement a snake in 50 lines of code, in order to illustrate one of the ways I practice programming on my own -- writing code short, in order to understand the language details.

 
<SPAN style="FONT-SIZE: 14px">import sys, pygame 
from pygame.locals import * 
from random import randrange 
up =lambda x:(x[0]-1,x[1]) 
down = lambda x :(x[0]+1,x[1]) 
left = lambda x : (x[0],x[1]-1) 
right = lambda x : (x[0],x[1]+1) 
tl = lambda x :x<3 and x+1 or 0 
tr = lambda x :x==0 and 3 or x-1 
dire = [up,left,down,right] 
move = lambda x,y:[y(x[0])]+x[:-1] 
grow = lambda x,y:[y(x[0])]+x 
s = [(5,5),(5,6),(5,7)] 
d = up 
food = randrange(0,30),randrange(0,40) 
FPSCLOCK=pygame.time.Clock() 
pygame.init() 
pygame.display.set_mode((800,600)) 
pygame.mouse.set_visible(0) 
screen = pygame.display.get_surface() 
screen.fill((0,0,0)) 
times=0.0 
while True: 
time_passed = FPSCLOCK.tick(30) 
if times>=150: 
times =0.0 
s = move(s,d) 
else: 
times +=time_passed 
for event in pygame.event.get(): 
if event.type == QUIT: 
sys.exit() 
if event.type == KEYDOWN and event.key == K_UP: 
s = move(s,d) 
if event.type == KEYDOWN and event.key == K_LEFT: 
d=dire[tl(dire.index(d))] 
if event.type == KEYDOWN and event.key == K_RIGHT: 
d=dire[tr(dire.index(d))] 
if s[0]==food: 
s = grow(s,d) 
food =randrange(0,30),randrange(0,40) 
if s[0] in s[1:] or s[0][0]<0 or s[0][0] >= 30 or s[0][1]<0 or s[0][1]>=40: 
break 
screen.fill((0,0,0)) 
for r,c in s: 
pygame.draw.rect(screen,(255,0,0),(c*20,r*20,20,20)) 
pygame.draw.rect(screen,(0,255,0),(food[1]*20,food[0]*20,20,20)) 
pygame.display.update()</SPAN> 

Screenshot of the game:
< img SRC = "border = 0 / / files.jb51.net/file_images/article/201304/2013427145053477.png? 2013327145126 ">
Description:
1. In fact, don't use pygame, in some conditions to judge changes, estimates can be short half. After their python level is high again to try again.
2. But 50 lines of snake code, or readable, write too short to really no.
3. The key is to rotate, move, and so on these algorithms with lamda expression, and function objects.
4. Which "walker" can write shorter, little brother is willing to give advice...
Author: aiqier