address feedback

build.sbt

@@ -393,9 +393,8 @@ def mimaSettings(moduleName: String) = Seq(
       exclude[ReversedMissingMethodProblem]("cats.kernel.instances.MapInstances.catsKernelStdCommutativeMonoidForMap"),
       exclude[IncompatibleResultTypeProblem]("cats.data.KleisliInstances0.catsDataMonadForKleisliId"),
       exclude[InheritedNewAbstractMethodProblem]("cats.kernel.PartialOrderToPartialOrderingConversion.catsKernelPartialOrderingForPartialOrder"),
-      exclude[InheritedNewAbstractMethodProblem]("cats.kernel.HashToHashingConversion.catsKernelHashToHashing"),
-      exclude[InheritedNewAbstractMethodProblem]("cats.kernel.PartialOrderToPartialOrderingConversion.catsKernelPartialOrderingForPartialOrder"),
-      exclude[InheritedNewAbstractMethodProblem]("cats.kernel.HashToHashingConversion.catsKernelHashToHashing")
+      exclude[InheritedNewAbstractMethodProblem]("cats.kernel.EqToEquivConversion.catsKernelEquivForEq"),
+      exclude[InheritedNewAbstractMethodProblem]("cats.kernel.OrderToOrderingConversion.catsKernelOrderingForOrder")
     )
   }
 )

core/src/main/scala/cats/instances/eq.scala

@@ -1,7 +1,7 @@
 package cats
 package instances
 
-trait EqInstances {
+trait EqInstances extends kernel.instances.EqInstances {
   implicit val catsContravariantMonoidalForEq: ContravariantMonoidal[Eq] =
     new ContravariantMonoidal[Eq] {
       /**

core/src/main/scala/cats/instances/hash.scala

@@ -2,7 +2,7 @@ package cats
 package instances
 
 
-trait HashInstances extends kernel.HashToHashingConversion {
+trait HashInstances {
 
   implicit val catsContravariantForHash: Contravariant[Hash] =
     new Contravariant[Hash] {

core/src/main/scala/cats/instances/order.scala

@@ -1,7 +1,7 @@
 package cats
 package instances
 
-trait OrderInstances extends cats.kernel.OrderToOrderingConversion {
+trait OrderInstances extends kernel.instances.OrderInstances {
   implicit val catsContravariantMonoidalForOrder: ContravariantMonoidal[Order] =
     new ContravariantMonoidal[Order] {
       /**

core/src/main/scala/cats/instances/partialOrder.scala

@@ -1,7 +1,7 @@
 package cats
 package instances
 
-trait PartialOrderInstances {
+trait PartialOrderInstances extends kernel.instances.PartialOrderInstances {
   implicit val catsContravariantSemigroupalForPartialOrder: ContravariantSemigroupal[PartialOrder] =
     new ContravariantSemigroupal[PartialOrder] {
       /** Derive a `PartialOrder` for `B` given a `PartialOrder[A]` and a function `B => A`.

core/src/main/scala/cats/instances/partialOrdering.scala

@@ -1,7 +1,7 @@
 package cats
 package instances
 
-trait PartialOrderingInstances extends kernel.PartialOrderToPartialOrderingConversion {
+trait PartialOrderingInstances {
   implicit val catsContravariantSemigroupalForPartialOrdering: ContravariantSemigroupal[PartialOrdering] =
     new ContravariantSemigroupal[PartialOrdering] {
       /** Derive a `PartialOrdering` for `B` given a `PartialOrdering[A]` and a function `B => A`.

kernel/src/main/scala/cats/kernel/Eq.scala

@@ -32,7 +32,17 @@ abstract class EqFunctions[E[T] <: Eq[T]] {
 
 }
 
-object Eq extends EqFunctions[Eq] {
+trait EqToEquivConversion {
+  /**
+   * Implicitly derive a `scala.math.Equiv[A]` from a `Eq[A]`
+   * instance.
+   */
+  implicit def catsKernelEquivForEq[A](implicit ev: Eq[A]): Equiv[A] = new Equiv[A] {
+    def equiv(a: A, b: A) = ev.eqv(a, b)
+  }
+}
+
+object Eq extends EqFunctions[Eq] with EqToEquivConversion {
 
   /**
    * Access an implicit `Eq[A]`.
@@ -66,13 +76,6 @@ object Eq extends EqFunctions[Eq] {
       def eqv(x: A, y: A) = eq1.eqv(x, y) || eq2.eqv(x, y)
     }
 
-  /**
-   * This gives compatibility with scala's Equiv trait
-   */
-  implicit def catsKernelEquivForEq[A](implicit ev: Eq[A]): Equiv[A] =
-    new Equiv[A] {
-      def equiv(a: A, b: A) = ev.eqv(a, b)
-    }
 
   /**
    * Create an `Eq` instance from an `eqv` implementation.

kernel/src/main/scala/cats/kernel/Hash.scala

@@ -54,9 +54,3 @@ 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)
-  }
-}

kernel/src/main/scala/cats/kernel/instances/all.scala

@@ -11,6 +11,7 @@ trait AllInstances
     with ByteInstances
     with CharInstances
     with DoubleInstances
+    with EqInstances
     with EitherInstances
     with DurationInstances
     with FloatInstances
@@ -20,6 +21,8 @@ trait AllInstances
     with LongInstances
     with MapInstances
     with OptionInstances
+    with OrderInstances
+    with PartialOrderInstances
     with QueueInstances
     with SetInstances
     with ShortInstances

kernel/src/main/scala/cats/kernel/instances/eq.scala

@@ -0,0 +1,6 @@
+package cats.kernel
+package instances
+
+trait EqInstances extends EqToEquivConversion
+
+object eq extends EqInstances

kernel/src/main/scala/cats/kernel/instances/order.scala

@@ -0,0 +1,6 @@
+package cats.kernel
+package instances
+
+trait OrderInstances extends OrderToOrderingConversion
+
+object order extends OrderInstances

kernel/src/main/scala/cats/kernel/instances/partialOrder.scala

@@ -0,0 +1,6 @@
+package cats.kernel
+package instances
+
+trait PartialOrderInstances extends PartialOrderToPartialOrderingConversion
+
+object partialOrder extends PartialOrderInstances