updated to Algebra 0.4.0

build.sbt

@@ -33,8 +33,8 @@ lazy val commonSettings = Seq(
   ),
   libraryDependencies ++= Seq(
     "com.github.mpilquist" %%% "simulacrum" % "0.7.0",
-    "org.spire-math" %%% "algebra" % "0.3.1",
-    "org.spire-math" %%% "algebra-std" % "0.3.1",
+    "org.spire-math" %%% "algebra" % "0.4.0",
+    "org.spire-math" %%% "algebra-std" % "0.4.0",
     "org.typelevel" %%% "machinist" % "0.4.1",
     compilerPlugin("org.scalamacros" %% "paradise" % "2.1.0" cross CrossVersion.full),
     compilerPlugin("org.spire-math" %% "kind-projector" % "0.6.3")

core/src/main/scala/cats/data/WriterT.scala

@@ -53,8 +53,6 @@ private[data] sealed abstract class WriterTInstances extends WriterTInstances0 {
   implicit def writerTIdMonad[L:Monoid]: Monad[WriterT[Id, L, ?]] =
     writerTMonadWriter[Id, L]
 
-  // The Eq[(L, V)] can be derived from an Eq[L] and Eq[V], but we are waiting
-  // on an algebra release that includes /~https://github.com/non/algebra/pull/82
   implicit def writerTIdEq[L, V](implicit E: Eq[(L, V)]): Eq[WriterT[Id, L, V]] =
     writerTEq[Id, L, V]
 

laws/src/main/scala/cats/laws/discipline/Eq.scala

@@ -4,6 +4,7 @@ package discipline
 
 import catalysts.Platform
 import algebra.Eq
+import algebra.std.tuple
 import cats.std.string._
 import org.scalacheck.Arbitrary
 
@@ -31,17 +32,9 @@ object eq {
       (a: A) => showInstance.show(a)
     }
 
-  // Temporary, see /~https://github.com/non/algebra/pull/82
-  implicit def tuple2Eq[A, B](implicit A: Eq[A], B: Eq[B]): Eq[(A, B)] =
-    new Eq[(A, B)] {
-      def eqv(x: (A, B), y: (A, B)): Boolean =
-        A.eqv(x._1, y._1) && B.eqv(x._2, y._2)
-    }
+  implicit def tuple2Eq[A, B](implicit A: Eq[A], B: Eq[B]): Eq[(A, B)] = tuple.tuple2Eq
 
-  implicit def tuple3Eq[A, B, C](implicit EqA: Eq[A], EqB: Eq[B], EqC: Eq[C]): Eq[(A, B, C)] =
-    new Eq[(A, B, C)] {
-      def eqv(x: (A, B, C), y: (A, B, C)): Boolean = EqA.eqv(x._1, y._1) && EqB.eqv(x._2, y._2) && EqC.eqv(x._3, y._3)
-    }
+  implicit def tuple3Eq[A, B, C](implicit EqA: Eq[A], EqB: Eq[B], EqC: Eq[C]): Eq[(A, B, C)] = tuple.tuple3Eq
 
   /**
    * Create an approximation of Eq[Semigroup[A]] by generating values for A