eq? eqv? equal?

参考：http://www.shido.info/lisp/scheme5_e.html

The eq?, eqv?, and equal? take exactly two arguments and are basic functions to check if the arguments are 'same'.These three functions are slightly different from each other.

eq?

     It compares addresses of two objects and returns #t if they are same.

eqv?

     It compares types and values of two object stored in the memory space.If both types and values are same, it returns #t.

equal?

     It is used to compare sequences such as list or string.

与这相关的有assq、assv、assoc，最快的是assq，最慢的是assoc