feat: migrate to scala 3

Author: Cristian Cantarero

build.sbt

@@ -1,5 +1,4 @@
 import sbtcrossproject.CrossPlugin.autoImport.crossProject
-import _root_.org.typelevel.sbt.tpolecat.TpolecatPlugin.autoImport._
 import _root_.org.typelevel.scalacoptions.ScalacOptions
 
 lazy val scalaVersion213 = "2.13.13"
@@ -83,10 +82,6 @@ val docs = project
   .dependsOn(coreJVM, mtlJVM)
   .enablePlugins(MicrositesPlugin, BuildInfoPlugin)
   .settings(
-    scalaVersion := scalaVersion213,
-    addCompilerPlugin(
-      "org.typelevel" %% "kind-projector" % "0.13.3" cross CrossVersion.full
-    ),
     tpolecatExcludeOptions ++= ScalacOptions.warnUnusedOptions,
     tpolecatExcludeOptions += ScalacOptions.warnNonUnitStatement,
     crossScalaVersions        := Nil,

modules/core/shared/src/main/scala/retry/Fibonacci.scala

@@ -2,10 +2,8 @@ package retry
 
 object Fibonacci {
   def fibonacci(n: Int): Long = {
-    if (n > 0)
-      fib(n)._1
-    else
-      0
+    if n > 0 then fib(n)._1
+    else 0
   }
 
   // "Fast doubling" Fibonacci algorithm.
@@ -16,9 +14,7 @@ object Fibonacci {
       val (a, b) = fib(m / 2)
       val c      = a * (b * 2 - a)
       val d      = a * a + b * b
-      if (n % 2 == 0)
-        (c, d)
-      else
-        (d, c + d)
+      if n % 2 == 0 then (c, d)
+      else (d, c + d)
   }
 }

modules/core/shared/src/main/scala/retry/RetryPolicies.scala

@@ -3,9 +3,9 @@ package retry
 import java.util.concurrent.TimeUnit
 
 import cats.Applicative
-import cats.syntax.functor._
-import cats.syntax.show._
-import retry.PolicyDecision._
+import cats.syntax.functor.*
+import cats.syntax.show.*
+import retry.PolicyDecision.*
 
 import scala.concurrent.duration.{Duration, FiniteDuration}
 import scala.util.Random
@@ -66,7 +66,7 @@ object RetryPolicies {
   def limitRetries[M[_]: Applicative](maxRetries: Int): RetryPolicy[M] =
     RetryPolicy.liftWithShow(
       { status =>
-        if (status.retriesSoFar >= maxRetries) {
+        if status.retriesSoFar >= maxRetries then {
           GiveUp
         } else {
           DelayAndRetry(Duration.Zero)
@@ -125,7 +125,7 @@ object RetryPolicies {
     def decideNextRetry(status: RetryStatus): M[PolicyDecision] =
       policy.decideNextRetry(status).map {
         case r @ DelayAndRetry(delay) =>
-          if (delay > threshold) GiveUp else r
+          if delay > threshold then GiveUp else r
         case GiveUp => GiveUp
       }
 
@@ -145,7 +145,7 @@ object RetryPolicies {
     def decideNextRetry(status: RetryStatus): M[PolicyDecision] =
       policy.decideNextRetry(status).map {
         case r @ DelayAndRetry(delay) =>
-          if (status.cumulativeDelay + delay >= threshold) GiveUp else r
+          if status.cumulativeDelay + delay >= threshold then GiveUp else r
         case GiveUp => GiveUp
       }
 

modules/core/shared/src/main/scala/retry/RetryPolicy.scala

@@ -2,12 +2,12 @@ package retry
 
 import cats.{Apply, Applicative, Monad, Functor}
 import cats.kernel.BoundedSemilattice
-import retry.PolicyDecision._
+import retry.PolicyDecision.*
 
 import scala.concurrent.duration.Duration
 import scala.concurrent.duration.FiniteDuration
 import cats.arrow.FunctionK
-import cats.implicits._
+import cats.implicits.*
 import cats.Show
 
 case class RetryPolicy[M[_]](

modules/core/shared/src/main/scala/retry/package.scala

@@ -1,7 +1,7 @@
 import cats.{Monad, MonadError}
-import cats.syntax.apply._
-import cats.syntax.functor._
-import cats.syntax.flatMap._
+import cats.syntax.apply.*
+import cats.syntax.functor.*
+import cats.syntax.flatMap.*
 
 import scala.concurrent.duration.FiniteDuration
 

modules/core/shared/src/test/scala/retry/PackageObjectSuite.scala

@@ -4,7 +4,7 @@ import cats.Id
 import munit.FunSuite
 
 import scala.collection.mutable.ArrayBuffer
-import scala.concurrent.duration._
+import scala.concurrent.duration.*
 
 class PackageObjectSuite extends FunSuite {
   type StringOr[A] = Either[String, A]
@@ -118,10 +118,8 @@ class PackageObjectSuite extends FunSuite {
       onError
     ) {
       attempts = attempts + 1
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Right("yay")
+      if attempts < 3 then Left("one more time")
+      else Right("yay")
     }
 
     assertEquals(finalResult, Right("yay"))
@@ -141,10 +139,8 @@ class PackageObjectSuite extends FunSuite {
       onError
     ) {
       attempts = attempts + 1
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Left("nope")
+      if attempts < 3 then Left("one more time")
+      else Left("nope")
     }
 
     assertEquals(finalResult, Left("nope"))
@@ -208,10 +204,8 @@ class PackageObjectSuite extends FunSuite {
       onError
     ) {
       attempts = attempts + 1
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Right("yay")
+      if attempts < 3 then Left("one more time")
+      else Right("yay")
     }
 
     assertEquals(finalResult, Right("yay"))
@@ -273,10 +267,8 @@ class PackageObjectSuite extends FunSuite {
       onError
     ) {
       attempts = attempts + 1
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Right("yay")
+      if attempts < 3 then Left("one more time")
+      else Right("yay")
     }
 
     assertEquals(finalResult, Right("yay"))
@@ -298,10 +290,8 @@ class PackageObjectSuite extends FunSuite {
       onError
     ) {
       attempts = attempts + 1
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Left("nope")
+      if attempts < 3 then Left("one more time")
+      else Left("nope")
     }
 
     assertEquals(finalResult, Left("nope"))
@@ -418,10 +408,8 @@ class PackageObjectSuite extends FunSuite {
       onError
     ) {
       attempts = attempts + 1
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Right("yay")
+      if attempts < 3 then Left("one more time")
+      else Right("yay")
     }
 
     assertEquals(finalResult, Right("yay"))

modules/core/shared/src/test/scala/retry/RetryPoliciesSuite.scala

@@ -2,14 +2,14 @@ package retry
 
 import java.util.concurrent.TimeUnit
 
-import retry.RetryPolicies._
+import retry.RetryPolicies.*
 import cats.Id
 import org.scalacheck.{Arbitrary, Gen}
 import org.scalacheck.Prop.forAll
 import munit.ScalaCheckSuite
 import retry.PolicyDecision.{DelayAndRetry, GiveUp}
 
-import scala.concurrent.duration._
+import scala.concurrent.duration.*
 import munit.Location
 
 class RetryPoliciesSuite extends ScalaCheckSuite {
@@ -137,7 +137,7 @@ class RetryPoliciesSuite extends ScalaCheckSuite {
         arbitraryCumulativeDelay,
         arbitraryPreviousDelay
       )
-      for (_ <- 1 to 1000) {
+      for _ <- 1 to 1000 do {
         val verdict = policy.decideNextRetry(status)
         val delay   = verdict.asInstanceOf[PolicyDecision.DelayAndRetry].delay
         assert(delay >= Duration.Zero)
@@ -170,7 +170,7 @@ class RetryPoliciesSuite extends ScalaCheckSuite {
       val limit = 500
       val verdict =
         limitRetries[Id](limit).decideNextRetry(status)
-      if (status.retriesSoFar < limit) {
+      if status.retriesSoFar < limit then {
         verdict == PolicyDecision.DelayAndRetry(Duration.Zero)
       } else {
         verdict == PolicyDecision.GiveUp

modules/core/shared/src/test/scala/retry/RetryPolicyLawsSuite.scala

@@ -1,13 +1,13 @@
 package retry
 
-import cats.instances.all._
+import cats.instances.all.*
 import cats.{Eq, Monoid, Id}
 import cats.kernel.laws.discipline.BoundedSemilatticeTests
 import munit.DisciplineSuite
 import org.scalacheck.{Arbitrary, Cogen, Gen}
 import org.scalacheck.Prop.*
 
-import scala.concurrent.duration._
+import scala.concurrent.duration.*
 import cats.laws.discipline.ExhaustiveCheck
 import cats.laws.discipline.eq.catsLawsEqForFn1Exhaustive
 import cats.arrow.FunctionK

modules/core/shared/src/test/scala/retry/RetryPolicySuite.scala

@@ -1,10 +1,10 @@
 package retry
 
 import cats.Id
-import cats.syntax.semigroup._
+import cats.syntax.semigroup.*
 import munit.FunSuite
 
-import scala.concurrent.duration._
+import scala.concurrent.duration.*
 
 class RetryPolicySuite extends FunSuite {
 

modules/core/shared/src/test/scala/retry/SyntaxSuite.scala

@@ -2,10 +2,10 @@ package retry
 
 import cats.Id
 import munit.FunSuite
-import retry.syntax.all._
+import retry.syntax.all.*
 
 import scala.collection.mutable.ArrayBuffer
-import scala.concurrent.duration._
+import scala.concurrent.duration.*
 
 class SyntaxSuite extends FunSuite {
   type StringOr[A] = Either[String, A]
@@ -96,10 +96,8 @@ class SyntaxSuite extends FunSuite {
 
     def action: StringOr[String] = {
       incrementAttempts()
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Right("yay")
+      if attempts < 3 then Left("one more time")
+      else Right("yay")
     }
 
     val finalResult: StringOr[String] =
@@ -125,10 +123,8 @@ class SyntaxSuite extends FunSuite {
 
     def action: StringOr[Nothing] = {
       incrementAttempts()
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Left("nope")
+      if attempts < 3 then Left("one more time")
+      else Left("nope")
     }
 
     val finalResult =
@@ -186,10 +182,8 @@ class SyntaxSuite extends FunSuite {
 
     def action: StringOr[String] = {
       incrementAttempts()
-      if (attempts < 3)
-        Left("one more time")
-      else
-        Right("yay")
+      if attempts < 3 then Left("one more time")
+      else Right("yay")
     }
 
     val finalResult: StringOr[String] =

modules/docs/src/main/scala/util/FlakyHttpClient.scala

@@ -7,7 +7,7 @@ case class FlakyHttpClient() {
   private var i = 0
 
   def getCatGif(): String = {
-    if (i > 3) {
+    if i > 3 then {
       "cute cat gets sleepy and falls asleep"
     } else {
       i = i + 1
@@ -16,9 +16,9 @@ case class FlakyHttpClient() {
   }
 
   def getRecordDetails(id: String): String = {
-    if (i > 3) {
+    if i > 3 then {
       "got some sweet details"
-    } else if (i == 0) {
+    } else if i == 0 then {
       i = i + 1
       throw new TimeoutException("Timed out getting details")
     } else {

modules/docs/src/main/scala/util/LoadedDie.scala

@@ -5,7 +5,7 @@ case class LoadedDie(rolls: Int*) {
 
   def roll(): Int = {
     i = i + 1
-    if (i >= rolls.length) {
+    if i >= rolls.length then {
       i = 0
     }
     rolls(i)

modules/mtl/shared/src/main/scala/retry/mtl/package.scala

@@ -2,9 +2,9 @@ package retry
 
 import cats.Monad
 import cats.mtl.Handle
-import cats.syntax.apply._
-import cats.syntax.flatMap._
-import cats.syntax.functor._
+import cats.syntax.apply.*
+import cats.syntax.flatMap.*
+import cats.syntax.functor.*
 
 package object mtl {
 

modules/mtl/shared/src/test/scala/retry/mtl/PackageObjectSuite.scala

@@ -5,7 +5,7 @@ import munit.FunSuite
 import retry.{RetryDetails, RetryPolicies, Sleep}
 
 import scala.collection.mutable.ArrayBuffer
-import scala.concurrent.duration._
+import scala.concurrent.duration.*
 
 class PackageObjectSuite extends FunSuite {
   type ErrorOr[A] = Either[Throwable, A]
@@ -49,10 +49,8 @@ class PackageObjectSuite extends FunSuite {
       retryingOnSomeErrors(policy, isWorthRetrying, onMtlError) {
         attempts = attempts + 1
 
-        if (attempts < 3)
-          EitherT.leftT[ErrorOr, String]("one more time")
-        else
-          EitherT.pure[ErrorOr, String]("yay")
+        if attempts < 3 then EitherT.leftT[ErrorOr, String]("one more time")
+        else EitherT.pure[ErrorOr, String]("yay")
       }
 
     assertEquals(finalResult.value, Right(Right("yay")))
@@ -73,10 +71,8 @@ class PackageObjectSuite extends FunSuite {
       retryingOnSomeErrors(policy, isWorthRetrying, onMtlError) {
         attempts = attempts + 1
 
-        if (attempts < 3)
-          EitherT.leftT[ErrorOr, String]("one more time")
-        else
-          EitherT.leftT[ErrorOr, String]("nope")
+        if attempts < 3 then EitherT.leftT[ErrorOr, String]("one more time")
+        else EitherT.leftT[ErrorOr, String]("nope")
       }
 
     assertEquals(finalResult.value, Right(Left("nope")))
@@ -138,10 +134,8 @@ class PackageObjectSuite extends FunSuite {
     val finalResult = retryingOnAllErrors(policy, onMtlError) {
       attempts = attempts + 1
 
-      if (attempts < 3)
-        EitherT.leftT[ErrorOr, String]("one more time")
-      else
-        EitherT.pure[ErrorOr, String]("yay")
+      if attempts < 3 then EitherT.leftT[ErrorOr, String]("one more time")
+      else EitherT.pure[ErrorOr, String]("yay")
     }
 
     assertEquals(finalResult.value, Right(Right("yay")))

modules/mtl/shared/src/test/scala/retry/mtl/SyntaxSuite.scala

@@ -3,12 +3,12 @@ package retry.mtl
 import cats.data.EitherT
 import cats.data.EitherT.catsDataMonadErrorFForEitherT
 import munit.FunSuite
-import retry.syntax.all._
-import retry.mtl.syntax.all._
+import retry.syntax.all.*
+import retry.mtl.syntax.all.*
 import retry.{RetryDetails, RetryPolicies, RetryPolicy, Sleep}
 
 import scala.collection.mutable.ArrayBuffer
-import scala.concurrent.duration._
+import scala.concurrent.duration.*
 
 class SyntaxSuite extends FunSuite {
   type ErrorOr[A] = Either[Throwable, A]