Add instantiation of MeasureDuration from cats-helper instance (#260)

* Add implicit instantiation of MeasureDuration from cats-helper instance

* Make conversion explicit

* Add reverse conversion

Author: i-surkov

build.sbt

@@ -44,6 +44,7 @@ lazy val smetrics = (project
     libraryDependencies ++= Seq(
       Cats.core,
       Cats.effect,
+      `cats-helper` % Optional,
       `cats-helper` % Test,
       scalatest % Test),
     libraryDependencies ++= crossSettings(

smetrics/src/main/scala/com/evolutiongaming/smetrics/MeasureDuration.scala

@@ -3,6 +3,7 @@ package com.evolutiongaming.smetrics
 import cats.effect.Clock
 import cats.implicits._
 import cats.{Applicative, FlatMap, ~>}
+import com.evolutiongaming.catshelper
 
 import scala.concurrent.duration._
 
@@ -29,6 +30,11 @@ object MeasureDuration {
     fromClock1(clock, FlatMap[F])
   }
 
+  def fromCatsHelper[F[_]](implicit csMeasureDuration: catshelper.MeasureDuration[F]): MeasureDuration[F] =
+    new MeasureDuration[F] {
+      override def start: F[F[FiniteDuration]] = csMeasureDuration.start
+    }
+
   implicit def fromClock1[F[_]: Clock: FlatMap]: MeasureDuration[F] = {
     val duration = for {
       duration <- Clock[F].monotonic
@@ -58,6 +64,10 @@ object MeasureDuration {
 
       val start: G[G[FiniteDuration]] = f(self.start.map(f.apply))
     }
+
+    def toCatsHelper: catshelper.MeasureDuration[F] = new catshelper.MeasureDuration[F] {
+      override def start: F[F[FiniteDuration]] = self.start
+    }
   }
 
-}
+}