It's hard to describe what immutable/persistent data structures do to your thinking. A lot of responsibilities move to the edges and you're left being able to

It's hard to describe what immutable/persistent data structures do to your thinking. A lot of responsibilities move to the edges and you're left being able to think and tests pieces of code in isolation. The repl becomes usable, and you code from inside your running program. It's a steep step to get started but it's going to transform how you think about some problems.