Add Chain (#2371)

* Add Catenable

* Add law tests and simple arbitrary and eq instances

* More tests

* Add benchmarks

* Add chain benchmarks

* Add Iterator

* More chain benchmarks

* Add Paul and Pavel to Authors and change COPYING to Cats Contributors

* More Tests

* Add reverse, groupBy and zipWith

* Add Collection Wrapping optimization

* Add traverse and foldRight implementations that don't convert to List

* Rename to Chain; add reverseIterator

* More efficient implementations

* Use Vector for reversing

* Remove redundant benchmarking methods

* Format scaladoc consistently

* Rename snoc and cons to append and prepend for consistency

* Add proper Eq, PartialOrder, Order and Coflatmap instances

AUTHORS.md

@@ -149,8 +149,10 @@ possible:
  * P. Oscar Boykin
  * Paolo G. Giarrusso
  * Pascal Voitot
+ * Paul Chiusano
  * Paul Phillips
  * Paulo "JCranky" Siqueira
+ * Pavel Chlupacek
  * Pavkin Vladimir
  * Pepe García
  * Pere Villega

COPYING

@@ -1,4 +1,4 @@
-Cats Copyright (c) 2015 Erik Osheim.
+Cats Copyright (c) 2015 Cats Contributors.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of
 this software and associated documentation files (the "Software"), to deal in

bench/src/main/scala/cats/bench/ChainBench.scala

@@ -0,0 +1,79 @@
+package cats.bench
+
+import cats.data.Chain
+import fs2.Catenable
+import chain.{Chain => OldChain}
+import org.openjdk.jmh.annotations.{Benchmark, Scope, State}
+
+@State(Scope.Thread)
+class ChainBench {
+
+  private val smallChain = Chain(1, 2, 3, 4, 5)
+  private val smallCatenable = Catenable(1, 2, 3, 4, 5)
+  private val smallVector = Vector(1, 2, 3, 4, 5)
+  private val smallList = List(1, 2, 3, 4, 5)
+  private val smallOldChain = OldChain(smallList)
+
+  private val largeChain = (0 to 1000)
+    .foldLeft(Chain.empty[Int])((acc, _) => acc ++ Chain.fromSeq(0 to 1000))
+  private val largeCatenable = Catenable.fromSeq(0 to 1000000)
+  private val largeVector = (0 to 1000000).toVector
+  private val largeList = (0 to 1000000).toList
+  private val largeOldChain = (0 to 1000).foldLeft(OldChain.empty[Int])((acc, _) => acc ++ OldChain(0 to 1000))
+
+
+  @Benchmark def mapSmallChain: Chain[Int] = smallChain.map(_ + 1)
+  @Benchmark def mapSmallCatenable: Catenable[Int] = smallCatenable.map(_ + 1)
+  @Benchmark def mapSmallVector: Vector[Int] = smallVector.map(_ + 1)
+  @Benchmark def mapSmallList: List[Int] = smallList.map(_ + 1)
+  @Benchmark def mapSmallOldChain: OldChain[Int] = smallOldChain.map(_ + 1)
+
+
+  @Benchmark def mapLargeChain: Chain[Int] = largeChain.map(_ + 1)
+  @Benchmark def mapLargeCatenable: Catenable[Int] = largeCatenable.map(_ + 1)
+  @Benchmark def mapLargeVector: Vector[Int] = largeVector.map(_ + 1)
+  @Benchmark def mapLargeList: List[Int] = largeList.map(_ + 1)
+  @Benchmark def mapLargeOldChain: OldChain[Int] = largeOldChain.map(_ + 1)
+
+
+
+  @Benchmark def foldLeftSmallChain: Int = smallChain.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftSmallCatenable: Int = smallCatenable.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftSmallVector: Int = smallVector.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftSmallList: Int = smallList.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftSmallOldChain: Int = smallOldChain.foldLeft(0)(_ + _)
+
+
+  @Benchmark def foldLeftLargeChain: Int = largeChain.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftLargeCatenable: Int = largeCatenable.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftLargeVector: Int = largeVector.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftLargeList: Int = largeList.foldLeft(0)(_ + _)
+  @Benchmark def foldLeftLargeOldChain: Int = largeOldChain.foldLeft(0)(_ + _)
+
+
+
+
+  @Benchmark def consSmallChain: Chain[Int] = 0 +: smallChain
+  @Benchmark def consSmallCatenable: Catenable[Int] = 0 +: smallCatenable
+  @Benchmark def consSmallVector: Vector[Int] = 0 +: smallVector
+  @Benchmark def consSmallList: List[Int] = 0 +: smallList
+  @Benchmark def consSmallOldChain: OldChain[Int] = 0 +: smallOldChain
+
+  @Benchmark def consLargeChain: Chain[Int] = 0 +: largeChain
+  @Benchmark def consLargeCatenable: Catenable[Int] = 0 +: largeCatenable
+  @Benchmark def consLargeVector: Vector[Int] = 0 +: largeVector
+  @Benchmark def consLargeList: List[Int] = 0 +: largeList
+  @Benchmark def consLargeOldChain: OldChain[Int] = 0 +: largeOldChain
+
+  @Benchmark def createTinyChain: Chain[Int] = Chain(1)
+  @Benchmark def createTinyCatenable: Catenable[Int] = Catenable(1)
+  @Benchmark def createTinyVector: Vector[Int] = Vector(1)
+  @Benchmark def createTinyList: List[Int] = List(1)
+  @Benchmark def createTinyOldChain: OldChain[Int] = OldChain.single(1)
+
+  @Benchmark def createSmallChain: Chain[Int] = Chain(1, 2, 3, 4, 5)
+  @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 createSmallOldChain: OldChain[Int] = OldChain(Seq(1, 2, 3, 4, 5))
+}

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

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

build.sbt

@@ -491,7 +491,10 @@ 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",
+    "co.fs2" %% "fs2-core" % "0.10.4"
+  ))
   .enablePlugins(JmhPlugin)
 
 // cats-js is JS-only