From b77f872bb976251d6cb09eda3e08b4542b9f35bc Mon Sep 17 00:00:00 2001
From: Anton Maminov <anton.linux@gmail.com>
Date: Tue, 30 Apr 2024 12:25:57 +0300
Subject: [PATCH] more operations

---
 spec/haversine/distance_spec.cr | 1 +
 src/haversine/distance.cr       | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/spec/haversine/distance_spec.cr b/spec/haversine/distance_spec.cr
index 519627c..bf72999 100644
--- a/spec/haversine/distance_spec.cr
+++ b/spec/haversine/distance_spec.cr
@@ -23,5 +23,6 @@ describe Haversine::Distance do
 
     it { (dist1 + dist2).distance.should eq(3) }
     it { (dist1 - dist2).distance.should eq(1) }
+    it { [dist1, dist2].sum.distance.should eq(3) }
   end
 end
diff --git a/src/haversine/distance.cr b/src/haversine/distance.cr
index 30bd6a4..81406fb 100644
--- a/src/haversine/distance.cr
+++ b/src/haversine/distance.cr
@@ -17,6 +17,10 @@ module Haversine
       distance <=> other.distance
     end
 
+    def self.zero : Haversine::Distance
+      new(0)
+    end
+
     # Adds the value of `self` to *other*.
     def +(other : Haversine::Distance) : Haversine::Distance
       Haversine::Distance.new(distance + other.distance)