Convert back multi-method type class instances to anonymous classes

Author: joroKr21

kernel/src/main/scala/cats/kernel/CommutativeGroup.scala

@@ -14,14 +14,4 @@ object CommutativeGroup extends GroupFunctions[CommutativeGroup] {
    * Access an implicit `CommutativeGroup[A]`.
    */
   @inline final def apply[A](implicit ev: CommutativeGroup[A]): CommutativeGroup[A] = ev
-
-  /**
-   * Create a `CommutativeGroup` instance from the given inverse and combine functions and empty value.
-   */
-  @inline def instance[A](emp: A, inv: A => A, cmb: (A, A) => A): CommutativeGroup[A] =
-    new CommutativeGroup[A] {
-      val empty = emp
-      def inverse(a: A) = inv(a)
-      def combine(x: A, y: A) = cmb(x, y)
-    }
 }

kernel/src/main/scala/cats/kernel/Group.scala

@@ -74,14 +74,4 @@ object Group extends GroupFunctions[Group] {
    * Access an implicit `Group[A]`.
    */
   @inline final def apply[A](implicit ev: Group[A]): Group[A] = ev
-
-  /**
-   * Create a `Group` instance from the given inverse and combine functions and empty value.
-   */
-  @inline def instance[A](emp: A, inv: A => A, cmb: (A, A) => A): Group[A] =
-    new Group[A] {
-      val empty = emp
-      def inverse(a: A) = inv(a)
-      def combine(x: A, y: A) = cmb(x, y)
-    }
 }

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

@@ -53,15 +53,6 @@ object Hash extends HashFunctions[Hash] {
       def hash(x: A) = x.hashCode()
       def eqv(x: A, y: A) = x == y
     }
-
-  /**
-   * Create a `Hash` instance from the given hash and equality functions.
-   */
-  @inline def instance[A](h: A => Int, e: (A, A) => Boolean): Hash[A] =
-    new Hash[A] {
-      def hash(x: A) = h(x)
-      def eqv(x: A, y: A) = e(x, y)
-    }
 }
 
 trait HashToHashingConversion {

project/KernelBoiler.scala

@@ -267,11 +267,11 @@ object KernelBoiler {
                 block"""
                 |  implicit def catsKernelCommutativeGroupForTuple$arity[${`A..N`}](
                 |    implicit ${constraints("CommutativeGroup")}
-                |  ): CommutativeGroup[${`(A..N)`}] = CommutativeGroup.instance(
-                |    ${nullaryTuple("empty")},
-                |    x => ${unaryTuple("inverse")},
-                |    (x, y) => ${binTuple("combine")}
-                |  )"""
+                |  ): CommutativeGroup[${`(A..N)`}] = new CommutativeGroup[${`(A..N)`}] {
+                |    def empty = ${nullaryTuple("empty")}
+                |    def inverse(x: ${`(A..N)`}) = ${unaryTuple("inverse")}
+                |    def combine(x: ${`(A..N)`}, y: ${`(A..N)`}) = ${binTuple("combine")}
+                |  }"""
             }
         ),
         InstanceDef(
@@ -326,11 +326,11 @@ object KernelBoiler {
                 block"""
                 |  implicit def catsKernelGroupForTuple$arity[${`A..N`}](
                 |    implicit ${constraints("Group")}
-                |  ): Group[${`(A..N)`}] = Group.instance(
-                |    ${nullaryTuple("empty")},
-                |    x => ${unaryTuple("inverse")},
-                |    (x, y) => ${binTuple("combine")}
-                |  )"""
+                |  ): Group[${`(A..N)`}] = new Group[${`(A..N)`}] {
+                |    def empty = ${nullaryTuple("empty")}
+                |    def inverse(x: ${`(A..N)`}) = ${unaryTuple("inverse")}
+                |    def combine(x: ${`(A..N)`}, y: ${`(A..N)`}) = ${binTuple("combine")}
+                |  }"""
             }
         ),
         InstanceDef(
@@ -342,10 +342,12 @@ object KernelBoiler {
                 block"""
                 |  implicit def catsKernelHashForTuple$arity[${`A..N`}](
                 |    implicit ${constraints("Hash")}
-                |  ): Hash[${`(A..N)`}] = Hash.instance(
-                |    x => ${unaryMethod("hash").mkString(s"$tupleNHeader(", ", ", ")")}.hashCode(),
-                |    (x, y) => ${binMethod("eqv").mkString(" && ")}
-                |  )"""
+                |  ): Hash[${`(A..N)`}] = new Hash[${`(A..N)`}] {
+                |    def hash(x: ${`(A..N)`}) =
+                |      ${unaryMethod("hash").mkString(s"$tupleNHeader(", ", ", ")")}.hashCode()
+                |    def eqv(x: ${`(A..N)`}, y: ${`(A..N)`}) =
+                |      ${binMethod("eqv").mkString(" && ")}
+                |  }"""
             }
         ),
         InstanceDef(