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Merge pull request #22 from mwfogleman/recursive-continue-then-stay

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Add continue-then-stay example.
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Nathan Marz 2017-10-09 12:57:19 -07:00 committed by GitHub
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30
Using-Specter-Recursively.md
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@ -210,6 +210,30 @@ Here are some other examples of using Specter recursively with `recursive-path`.
{:a {:aaa 4, :b {:c {:aaa 3}, :aaa 2}}}
```
## Recursively navigate to every map in a map of maps
You have a deeply nested map of maps:
```clojure
(def data
{:a {:b {:c 1} :d 2}
:e {:f 3 :g 4}})
```
You want to recursively navigate this data structure and add a key-value pair to every map at every level. This example, `MAP-NODES`, shows you how to do so:
```clojure
=> (def MAP-NODES
(recursive-path [] p
(if-path map?
(continue-then-stay MAP-VALS p))))
=> (setval [MAP-NODES :X] 0 data)
{:a {:b {:c 1, :X 0}, :d 2, :X 0}, :e {:f 3, :g 4, :X 0}, :X 0}
```
`MAP-NODES` illustrates how to combine recursive paths with `[continue-then-stay](https://github.com/nathanmarz/specter/wiki/List-of-Navigators#continue-then-stay)`, which navigates to the provided path and then to the current element. This should also point to how you might use recursive paths with `[stay-then-continue](https://github.com/nathanmarz/specter/wiki/List-of-Navigators#stay-then-continue)`, which navigates to the current element and then to the provided path.
## Find the "index route" of a value within a data structure
This example comes from [a Stack Overflow question](https://stackoverflow.com/questions/45764946/how-to-find-indexes-in-deeply-nested-data-structurevectors-and-lists-in-clojur).
@ -220,9 +244,9 @@ This example comes from [a Stack Overflow question](https://stackoverflow.com/qu
(if-path sequential?
[INDEXED-VALS
(if-path [LAST (pred= v)]
FIRST
[(collect-one FIRST) LAST p])]))
ret (select-first walker data)]
FIRST
[(collect-one FIRST) LAST p])]))
ret (select-first walker data)]
(if (or (vector? ret) (nil? ret)) ret [ret])))
#'playground.specter/find-index-route
=> (find-index-route :my-key '(1 2 :my-key))