I think this is perhaps only a repository for keeping things or approaches, which has surfaced here, because of the fame of the author. The results and code mi

I think this is perhaps only a repository for keeping things or approaches, which has surfaced here, because of the fame of the author. The results and code might be rather individual preferences or ad-hoc solutions to typical problems. The data in the example does not require a lot of recursion to be elegantly processed. It is too simple an example for that. The second aspect is, that the example code might have different priorities than the viewer. If I want to process a tree concurrently on multiple cores, then perhaps I should not be using much mutable state. However, if my priority is not concurrency and multi-core, then perhaps I can write it in very little code in Python and similar languages. When my priorities shift to concurrency and multi-core and lets say I got a deeply nested tree, I might have to adapt all these examples and suddenly the FP languages shine.