From f70043f4757bd4be69f02c0d9ce4663ef429fa2f Mon Sep 17 00:00:00 2001
From: Mike Ryan <mike.ryan52@gmail.com>
Date: Sun, 27 Mar 2016 09:35:25 -0600
Subject: [PATCH] chore(docs): Add documentation about applySelector utility

---
 docs/utilities.md | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/docs/utilities.md b/docs/utilities.md
index 83bb41c..11e2b8a 100644
--- a/docs/utilities.md
+++ b/docs/utilities.md
@@ -66,3 +66,23 @@ return saga$ => saga$
   .map(toPayload)
   .do(payload => { ... });
 ```
+
+#### applySelector<T,V>(selector: Observable<T> => Observable<V>)
+Applies a selector function to the _state_ part of a saga iteration, returning
+a new saga iteration composed of the action and the selected piece of state
+
+__Params__
+* `selector` __Observable<T> => Observable<V>__ Selector function to apply to the state
+
+_Returns_ `Observable<SagaIteration<V>>`
+
+```ts
+function selectTodos() {
+  return (state$: Observable<{ todos: string[] }>) => state$
+    .map(s => s.todos)
+    .distinctUntilChanged();
+}
+
+return saga$ => saga$
+  .let(applySelector(selectTodos))
+```