1 files changed, 32 insertions, 0 deletions
diff --git a/src/main/scala/cc/spray/json/lenses/UpdateLens.scala b/src/main/scala/cc/spray/json/lenses/UpdateLens.scala
new file mode 100644
index 0000000..c532b15
--- /dev/null
+++ b/src/main/scala/cc/spray/json/lenses/UpdateLens.scala
@@ -0,0 +1,32 @@
+package cc.spray.json
+package lenses
+
+trait Update extends (JsValue => JsValue) {
+  outer =>
+  def apply(value: JsValue): JsValue
+
+  def &&(next: Update): Update = new Update {
+    def apply(value: JsValue): JsValue = next(outer(value))
+  }
+}
+
+/**
+ * The UpdateLens is the central interface for updating a child element somewhere
+ * deep down a hierarchy of a JsValue.
+ */
+trait UpdateLens {
+  /**
+   * Applies function `f` on the child of the `parent` denoted by this UpdateLens
+   * and returns a `Right` of the parent with the child element updated.
+   *
+   * The value passed to `f` may be `Left(e)` if the child could not be found
+   * in which case particular operations may still succeed. Function `f` may return
+   * `Left(error)` in case the operation fails.
+   *
+   * `updated` returns `Left(error)` if the update operation or any of any intermediate
+   * projections fail.
+   */
+  def updated(f: Operation)(parent: JsValue): SafeJsValue
+
+  def !(op: Operation): Update
+}
+\ No newline at end of file