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Nathan Marz 2016-04-20 22:20:45 -04:00
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@ -181,7 +181,7 @@ user> (select [ALL AccountPath :funds]
[50 51 1 2]
```
The next example demonstrates recursive navigation. Here's how to double all the even numbers in a tree:
The next examples demonstrate recursive navigation. Here's how to double all the even numbers in a tree:
```clojure
(defprotocolpath TreeWalker [])
@ -194,6 +194,26 @@ The next example demonstrates recursive navigation. Here's how to double all the
;; => [:a 1 [4 [[[3]]] :e] [8 5 [12 7]]]
```
Here's how to reverse the positions of all even numbers in a tree (with order based on a depth first search). This example uses conditional navigation instead of protocol paths to do the walk:
```clojure
(declarepath TreeValues)
(providepath TreeValues
(if-path vector?
[ALL TreeValues]
STAY
))
(transform (subselect TreeValues even?)
reverse
[1 2 [3 [[4]] 5] [6 [7 8] 9 [[10]]]]
)
;; => [1 10 [3 [[8]] 5] [6 [7 4] 9 [[2]]]]
```
You can make `select` and `transform` work much faster by precompiling your selectors using the `comp-paths` function. There's about a 3x speed difference between the following two invocations of transform:
```clojure