Recursion is mentioned a few times in this chapter, so perhaps rearrange so the recursion chapter comes first? I'll need to revisit this after I see that chapter.
Edit: After having read Chapter 9, I can see there's not a ton of overlap between the chapters. If you want to swap 8 and 9, that would be a minor improvement to Chapter 8, because the handful of mentions of recursion would be clearer. Chapter 9 doesn't depend on any of the list content found in 8 (that I can see), so I don't think there's any harm done in swapping them.
Filtering-Out and Filtering-In section
I don't think you need this heading here. The heading basically applies to everything you've been saying in the "Filter" section up to this point. If you want to have a heading here because you're defining the solution, then I suggest you add a parallel heading earlier where you define the problem.
Looking for Lists section
"If this version is harder for you read right now than the original," Well, yeah, it is, so thanks for that.
Beyond Lists section
In your definition of binary search trees, you should probably mention the "binary" part (each node has no more than two children).
Recursion is mentioned a few times in this chapter, so perhaps rearrange so the recursion chapter comes first? I'll need to revisit this after I see that chapter. Edit: After having read Chapter 9, I can see there's not a ton of overlap between the chapters. If you want to swap 8 and 9, that would be a minor improvement to Chapter 8, because the handful of mentions of recursion would be clearer. Chapter 9 doesn't depend on any of the list content found in 8 (that I can see), so I don't think there's any harm done in swapping them.
Filtering-Out and Filtering-In section
I don't think you need this heading here. The heading basically applies to everything you've been saying in the "Filter" section up to this point. If you want to have a heading here because you're defining the solution, then I suggest you add a parallel heading earlier where you define the problem.
Looking for Lists section
"If this version is harder for you read right now than the original," Well, yeah, it is, so thanks for that.
Beyond Lists section
In your definition of binary search trees, you should probably mention the "binary" part (each node has no more than two children).