diff --git a/Using-Specter-Recursively.md b/Using-Specter-Recursively.md index e52ed0a..b3678e0 100644 --- a/Using-Specter-Recursively.md +++ b/Using-Specter-Recursively.md @@ -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`, 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`, 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).