[Too]

Half of the list is equally premature conclusions. Without entertaining this too much: You have properties, slots, __setitem__, dict merging with inplace h1.update(h2) or returning {**h1, **h2, “key”:”toadd”}. Defaultdict being clunky, really? Mypy does catch assignment typos outside __init__. Chain failing on non-iterables sounds expected, what else should happen? Implicitly treating as list of 1…? Explicit returns is a good thing, it avoids ambiguity and allows static analysis on missing return paths or returning wrong type.

Still got some gems in there that python could benefit from. Like safe navigation and nested dig, you can sort of emulate it with .get(“top”, {}).get(..) but it’s messy.