unless(fboundp(‘HowFar) procedure(HowFar(a b) prog(() return(sqrt((car(a) - car(b)) ** 2 + (cadr(a) - cadr(b)) ** 2)) ) ) )
HowFar(0:0 1:1) =>1.414214
Skill计算两点距离
原文：https://www.cnblogs.com/yeungchie/p/12823609.html
