Reimplement coral::optional::and_then

source/coral.cpp

@@ -382,6 +382,13 @@ export namespace coral {
 			}
 		}
 
+		/**
+		 * Invokes the `apply` procedure if the optional is not empty, otherwise having no side-effects.
+		 */
+		void and_then(closure<void(element &)> const & apply) {
+			if (this->has_value()) apply(**this);
+		}
+
 		/**
 		 * Returns `true` if the optional contains a value, otherwise `false`.
 		 */