Add first class option catamorphism

jbgi · jbgi · commit 7c2605ec48ce · 2016-06-21T22:54:48.000+02:00
diff --git a/core/src/main/java/fj/data/Option.java b/core/src/main/java/fj/data/Option.java
@@ -688,6 +688,18 @@ public static <T> F<T, Option<T>> fromNull() {
     return Option::fromNull;
   }
 
+  /**
+   * First-class catamorphism for Option: return a function that will performs
+   * a reduction on an optional value using the given arguments.
+   *
+   * @param none The value to return if this optional value has no value.
+   * @param some The function to apply to the value of this optional value.
+   * @return the reducing function.
+   */
+  public static final <A, B> F<Option<A>, B> cata(final B none, final F<A, B> some) {
+    return o -> o.option(none, some);
+  }
+
   /**
    * Joins the given optional value of optional value using a bind operation.
    *
