这学期在学programming language，以scheme为基础的。
想请问下scheme高手

Accept as input a infix expression. The program should be
able to handle fairly complex and lengthy expressions. Convert
this infix expression into a postfix expression. For example,
the prefix expression (2+(4* 5))/(8-6) will be converted to the
postfix expression 245*+86-/.

该如何用 scheme来解决
输入用什么形式，是 string还是list，如何用 schme模拟一个 stack呢 ，谢谢