tree pattern matching

• 树型模式匹配

tree pattern matching的用法和样例：

例句

1. Contrast to an ameliorative pattern,which is a pattern that tells how to go from a bad solution to a good solution.
   与优秀的改进型模式相反，反模式告诉我们避免这些糟糕的模式采用优秀的模式。