Add chain benchmarks

bench/src/main/scala/cats/bench/CatenableBench.scala

@@ -1,8 +1,6 @@
 package cats.bench
 
 import cats.data.Catenable
-import cats.implicits._
-
 import org.openjdk.jmh.annotations.{Benchmark, Scope, State}
 
 @State(Scope.Thread)
@@ -47,8 +45,4 @@ class CatenableBenchmark {
   @Benchmark def createSmallCatenable: Catenable[Int] = Catenable(1, 2, 3, 4, 5)
   @Benchmark def createSmallVector: Vector[Int] = Vector(1, 2, 3, 4, 5)
   @Benchmark def createSmallList: List[Int] = List(1, 2, 3, 4, 5)
-
-  @Benchmark def accumulateCatenable: Catenable[Int] = largeList.foldMap(Catenable.singleton)
-  @Benchmark def accumulateVector: Vector[Int] = largeList.foldMap(Vector(_))
-  @Benchmark def accumulateList: List[Int] = largeList.foldMap(List(_))
 }

bench/src/main/scala/cats/bench/CollectionMonoidBench.scala

@@ -0,0 +1,24 @@
+package cats.bench
+
+import cats.Monoid
+import cats.data.Catenable
+import cats.implicits._
+import chain.Chain
+import org.openjdk.jmh.annotations.{Benchmark, Scope, State}
+
+@State(Scope.Thread)
+class CollectionMonoidBench {
+
+  private val largeList = (0 to 1000000).toList
+
+  implicit def monoidChain[A]: Monoid[Chain[A]] = new Monoid[Chain[A]] {
+    def empty: Chain[A] = Chain.empty[A]
+
+    def combine(x: Chain[A], y: Chain[A]): Chain[A] = x ++ y
+  }
+
+  @Benchmark def accumulateCatenable: Catenable[Int] = largeList.foldMap(Catenable.singleton)
+  @Benchmark def accumulateVector: Vector[Int] = largeList.foldMap(Vector(_))
+  @Benchmark def accumulateList: List[Int] = largeList.foldMap(List(_))
+  @Benchmark def accumulateChain: Chain[Int] = largeList.foldMap(Chain.single)
+}

build.sbt

@@ -491,7 +491,9 @@ lazy val bench = project.dependsOn(macrosJVM, coreJVM, freeJVM, lawsJVM)
   .settings(commonJvmSettings)
   .settings(coverageEnabled := false)
   .settings(libraryDependencies ++= Seq(
-    "org.scalaz" %% "scalaz-core" % "7.2.23"))
+    "org.scalaz" %% "scalaz-core" % "7.2.23",
+    "org.spire-math" %% "chain" % "0.3.0"
+  ))
   .enablePlugins(JmhPlugin)
 
 // cats-js is JS-only