# thread-first


## Navigation

[[thread-first]] `->` is ideal for navigating large, nested structures.

<code clojure>
(-> results
    :matches
    (nth 3)
    :scores
    (get "total_points"))
</code>

This works with Java objects too

<code clojure>
(-> results
    .getMatches
    (nth 3)
    .getScores
    (.getKey "total_points"))
</code>

## Transformation

The second use case of `->` is performing a series of functional transformations on a single value:

<code clojure>
(-> username
    string/trim
    string/lower-case
    (string/replace #"[^a-z]" "-"))
</code>

<code clojure>
(-> game-state
    (assoc :next-player :player2)
    (update :turn-counter inc)
    (update-in [:scores :player1] + 10)
    (update-in [:scores :player2] - 3))
</code>