Summary.md

4.11 Summary

本章将 flatMap 视为一种 排列计算（函数） 的 操作符，函数必须按照 flatMap 指定的 顺序 依次执行，从这个角度看：

• Option represents a computation that can fail without an error message
• Either represents computations that can fail with a message
• List represents multiple possible results
• Future represents a computation that may produce a value at some point in the future