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volrath / treepy.el

Generic tree traversing tools for Emacs Lisp
GNU General Public License v3.0
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Examples? #1

Open alphapapa opened 7 years ago

alphapapa commented 7 years ago

Hi,

This is really cool, thanks for sharing it.

It would help a lot to have some examples, especially for Emacers who haven't used Clojure before. I was hoping the links to the Clojure docs would have some examples, but it seems as sparse as the definitions here. :)

For example, treepy-walk seems confusing to me: from the docstring, it sounds like it applies inner to each leaf of the tree, but looking at the code, it doesn't seem like it would do that for a list like:

(list a
      (list b
            c))

Maybe I'm misunderstanding it, though.

Thanks.

volrath commented 7 years ago

Hey,

You are right, it's missing some examples.

For the time being, the best way to see the functions in action is by going through the tests, particularly:

https://github.com/volrath/treepy.el/blob/master/test/treepy.el-walker-test.el#L75 https://github.com/volrath/treepy.el/blob/master/test/treepy.el-walker-test.el#L103

Which show the traversal order for treepy-prewalk and treepy-postwalk respectively.

Regarding treepy-walk, it applies inner to each element of the given form. In your example list, it would apply inner to a and then to (list b c). treepy-walk doesn't really take care of recursion, that's the job for treepy-prewalk and treepy-postwalk. You can think of it as a helper function that you can use to create your own "walkers" or "reducers". This test might also help with that clarification.

Also, you can go through the zipper tests to see examples of the zipper structure. And Alex Miller's article on tree visitors in Clojure is really useful as well.

I'll leave this issue open and close it when better examples are provided. Thanks for the feedback!

alphapapa commented 7 years ago

Thanks!