Add Tree Keys

[mitchelllisle]

Hi! Big fan of funcy - thought I'd add something that I find really useful and I believe fits in with the library. Basically, this function allows you to generate a list of keys within a nested dict.

This can then be used to iterate over a dictionary and make sure you're able to access any level of nested dicts. For example:

Given

payload = {
    "foo": "bar",
    "parent": {
        "val": True,
        "child": {
            "foo": "bar"
        }
    }
}

ltree_keys returns a list: [['parent'], ['parent', 'child'], ['parent', 'child', 'foo'], ['parent', 'val'], ['foo']]

That then works nicely with funcy.get_in and the like - for example: fn.lmap(lambda x: type(fn.get_in(payload, x)), keys)

Happy to make any updates or add anything else I may have missed.

[Suor]

Hello, @mitchelllisle, thank for your involvement and sorry for slow feedback. There are, however, several issues with this:

• your usage example might be much easier implemented using tree_nodes(), doesn't look like you need key paths here. I need to see a valid and common enough use case to consider adding this - I try to keep funcy scope sane.
• fn.lmap(lambda x: type(fn.get_in(payload, x)), keys) is an inefficient because get_in() traverses those structures over and over. Lots of flattening inside also raise my consideration.
• your implementation is not generic enough, see follow and children args in tree_nodes() and tree_leaves(). You are simply calling .get() and checking collection class.

[Suor]

Feel free to reopen if you see something not covered above.