From 0f34e7cf8934b4538220f4c774635e27b92dec62 Mon Sep 17 00:00:00 2001
From: Kailuo Wang <kailuo.wang@gmail.com>
Date: Mon, 18 Dec 2017 11:13:40 -0500
Subject: [PATCH] added hash conversion

---
 core/src/main/scala/cats/instances/hash.scala          | 2 +-
 kernel/src/main/scala/cats/kernel/Hash.scala           | 6 ++++++
 kernel/src/main/scala/cats/kernel/instances/all.scala  | 1 +
 kernel/src/main/scala/cats/kernel/instances/hash.scala | 6 ++++++
 4 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 kernel/src/main/scala/cats/kernel/instances/hash.scala

diff --git a/core/src/main/scala/cats/instances/hash.scala b/core/src/main/scala/cats/instances/hash.scala
index 443ef96e394..2401313148a 100644
--- a/core/src/main/scala/cats/instances/hash.scala
+++ b/core/src/main/scala/cats/instances/hash.scala
@@ -2,7 +2,7 @@ package cats
 package instances
 
 
-trait HashInstances {
+trait HashInstances extends kernel.instances.HashInstances {
 
   implicit val catsContravariantForHash: Contravariant[Hash] =
     new Contravariant[Hash] {
diff --git a/kernel/src/main/scala/cats/kernel/Hash.scala b/kernel/src/main/scala/cats/kernel/Hash.scala
index ef8e88d742a..4579f121848 100644
--- a/kernel/src/main/scala/cats/kernel/Hash.scala
+++ b/kernel/src/main/scala/cats/kernel/Hash.scala
@@ -54,3 +54,9 @@ object Hash extends HashFunctions[Hash] {
     }
 
 }
+
+trait HashToHashingConversion {
+  implicit def catsKernelHashToHashing[A](implicit ev: Hash[A]): Hashing[A] = new Hashing[A] {
+    override def hash(x: A): Int = ev.hash(x)
+  }
+}
diff --git a/kernel/src/main/scala/cats/kernel/instances/all.scala b/kernel/src/main/scala/cats/kernel/instances/all.scala
index 1b5866c7c18..1af2f0b0dad 100644
--- a/kernel/src/main/scala/cats/kernel/instances/all.scala
+++ b/kernel/src/main/scala/cats/kernel/instances/all.scala
@@ -16,6 +16,7 @@ trait AllInstances
     with DurationInstances
     with FloatInstances
     with FunctionInstances
+    with HashInstances
     with IntInstances
     with ListInstances
     with LongInstances
diff --git a/kernel/src/main/scala/cats/kernel/instances/hash.scala b/kernel/src/main/scala/cats/kernel/instances/hash.scala
new file mode 100644
index 00000000000..38220965962
--- /dev/null
+++ b/kernel/src/main/scala/cats/kernel/instances/hash.scala
@@ -0,0 +1,6 @@
+package cats.kernel
+package instances
+
+trait HashInstances extends HashToHashingConversion
+
+object hash extends HashInstances