diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/Decoders.scala b/client/src/main/scala/org/scalaexercises/evaluator/Decoders.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/Decoders.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/Decoders.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/EvaluatorAPI.scala b/client/src/main/scala/org/scalaexercises/evaluator/EvaluatorAPI.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/EvaluatorAPI.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/EvaluatorAPI.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/EvaluatorClient.scala b/client/src/main/scala/org/scalaexercises/evaluator/EvaluatorClient.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/EvaluatorClient.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/EvaluatorClient.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/EvaluatorResponses.scala b/client/src/main/scala/org/scalaexercises/evaluator/EvaluatorResponses.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/EvaluatorResponses.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/EvaluatorResponses.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/api/Evaluator.scala b/client/src/main/scala/org/scalaexercises/evaluator/api/Evaluator.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/api/Evaluator.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/api/Evaluator.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/free/algebra/EvaluatorOps.scala b/client/src/main/scala/org/scalaexercises/evaluator/free/algebra/EvaluatorOps.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/free/algebra/EvaluatorOps.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/free/algebra/EvaluatorOps.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/free/interpreters/Interpreter.scala b/client/src/main/scala/org/scalaexercises/evaluator/free/interpreters/Interpreter.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/free/interpreters/Interpreter.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/free/interpreters/Interpreter.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/http/HttpClient.scala b/client/src/main/scala/org/scalaexercises/evaluator/http/HttpClient.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/http/HttpClient.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/http/HttpClient.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/http/HttpRequestBuilder.scala b/client/src/main/scala/org/scalaexercises/evaluator/http/HttpRequestBuilder.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/http/HttpRequestBuilder.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/http/HttpRequestBuilder.scala
diff --git a/client/shared/src/main/scala/org/scalaexercises/evaluator/implicits.scala b/client/src/main/scala/org/scalaexercises/evaluator/implicits.scala
similarity index 100%
rename from client/shared/src/main/scala/org/scalaexercises/evaluator/implicits.scala
rename to client/src/main/scala/org/scalaexercises/evaluator/implicits.scala
diff --git a/project/ProjectPlugin.scala b/project/ProjectPlugin.scala
index f4812a37..fa28911c 100644
--- a/project/ProjectPlugin.scala
+++ b/project/ProjectPlugin.scala
@@ -26,7 +26,7 @@ object ProjectPlugin extends AutoPlugin {
       lazy val roshttp     = "2.2.4"
       lazy val slf4jSimple = "1.7.28"
       lazy val jwtCore     = "4.0.0"
-      lazy val coursier    = "2.0.0-RC3-2"
+      lazy val coursier    = "2.0.0-RC3-4"
     }
 
     lazy val dockerSettings = Seq(
@@ -82,9 +82,11 @@ object ProjectPlugin extends AutoPlugin {
         %%("http4s-circe", V.http4s),
         %("config"),
         %%("jwt-core", V.jwtCore),
+        %%("coursier", V.coursier),
+        %%("coursier-cache", V.coursier),
+        "io.get-coursier"            %% "coursier-cats-interop" % V.coursier,
         %%("scalatest", V.scalatest) % "test"
-      ),
-      addSbtPlugin("io.get-coursier" % "sbt-coursier" % V.coursier)
+      )
     )
 
     lazy val buildInfoSettings = Seq(
@@ -136,7 +138,7 @@ object ProjectPlugin extends AutoPlugin {
         organizationEmail = "hello@47deg.com"
       ),
       orgLicenseSetting := ApacheLicense,
-      scalaVersion := "2.12.10",
+      scalaVersion := "2.11.11",
       scalaOrganization := "org.scala-lang",
       javacOptions ++= Seq("-encoding", "UTF-8", "-Xlint:-options"),
       fork in Test := false,
@@ -144,13 +146,11 @@ object ProjectPlugin extends AutoPlugin {
       cancelable in Global := true,
       headerLicense := Some(
         HeaderLicense.Custom(
-          s"""|/*
-            | * scala-exercises - ${name.value}
-            | * Copyright (C) 2015-2019 47 Degrees, LLC. <http://www.47deg.com>
-            | */
-            |
-            |""".stripMargin
-        )),
-      headerMappings := headerMappings.value + (HeaderFileType.scala -> HeaderCommentStyle.CStyleBlockComment)
+          s"""|
+            | scala-exercises - ${name.value}
+              | Copyright (C) 2015-2019 47 Degrees, LLC. <http://www.47deg.com>
+              |
+              |""".stripMargin
+        ))
     ) ++ shellPromptSettings
 }
diff --git a/server/src/main/scala/org/scalaexercises/evaluator/auth.scala b/server/src/main/scala/org/scalaexercises/evaluator/auth.scala
index e5e36730..f8a45c93 100644
--- a/server/src/main/scala/org/scalaexercises/evaluator/auth.scala
+++ b/server/src/main/scala/org/scalaexercises/evaluator/auth.scala
@@ -1,19 +1,21 @@
 /*
- * scala-exercises - evaluator-server
- * Copyright (C) 2015-2016 47 Degrees, LLC. <http://www.47deg.com>
+ *
+ *  scala-exercises - evaluator-server
+ *  Copyright (C) 2015-2019 47 Degrees, LLC. <http://www.47deg.com>
+ *
  */
 
 package org.scalaexercises.evaluator
 
-import org.http4s._, org.http4s.dsl._, org.http4s.server._
+import cats.effect.Sync
 import com.typesafe.config._
+import org.http4s._
+import org.http4s.syntax.kleisli.http4sKleisliResponseSyntax
 import org.http4s.util._
-import scala.util.{Failure, Success, Try}
-import pdi.jwt.{Jwt, JwtAlgorithm, JwtClaim, JwtHeader, JwtOptions}
-
 import org.log4s.getLogger
+import pdi.jwt.{Jwt, JwtAlgorithm}
 
-import scalaz.concurrent.Task
+import scala.util.{Failure, Success}
 
 object auth {
 
@@ -37,15 +39,14 @@ object auth {
 
     type HeaderT = `X-Scala-Eval-Api-Token`
 
-    def name: CaseInsensitiveString = "x-scala-eval-api-token".ci
+    def name: CaseInsensitiveString = CaseInsensitiveString("x-scala-eval-api-token")
 
     override def parse(s: String): ParseResult[`X-Scala-Eval-Api-Token`] =
       ParseResult.success(`X-Scala-Eval-Api-Token`(s))
 
-    def matchHeader(header: Header): Option[HeaderT] = {
+    def matchHeader(header: Header): Option[HeaderT] =
       if (header.name == name) Some(`X-Scala-Eval-Api-Token`(header.value))
       else None
-    }
 
   }
 
@@ -55,20 +56,26 @@ object auth {
       writer.append(token)
   }
 
-  def apply(service: HttpService): HttpService = Service.lift { req =>
-    req.headers.get(`X-Scala-Eval-Api-Token`) match {
-      case Some(header) =>
-        Jwt.decodeRaw(header.value, secretKey, Seq(JwtAlgorithm.HS256)) match {
-          case Success(tokenIdentity) =>
-            logger.info(s"Auth success with identity : $tokenIdentity")
-            service(req)
-          case Failure(ex) =>
-            logger.warn(s"Auth failed : $ex")
-            Task.now(Response(Status.Unauthorized))
+  def apply[F[_]: Sync](service: HttpApp[F]): HttpApp[F] =
+    HttpRoutes
+      .of[F] {
+        case req if req.headers.nonEmpty => {
+          req.headers.get(`X-Scala-Eval-Api-Token`) match {
+            case Some(header) =>
+              Jwt.decodeRaw(header.token, secretKey, Seq(JwtAlgorithm.HS256)) match {
+                case Success(tokenIdentity) => {
+                  logger.info(s"Auth success with identity : $tokenIdentity")
+                  service(req)
+                }
+                case Failure(ex) => {
+                  logger.warn(s"Auth failed : $ex")
+                  Sync[F].pure(Response(Status.Unauthorized))
+                }
+              }
+          }
         }
-      case None => Task.now(Response(Status.Unauthorized))
-    }
-
-  }
+        case _ => Sync[F].pure(Response(Status.Unauthorized))
+      }
+      .orNotFound
 
 }
diff --git a/server/src/main/scala/org/scalaexercises/evaluator/codecs.scala b/server/src/main/scala/org/scalaexercises/evaluator/codecs.scala
index bd092209..84c71eb6 100644
--- a/server/src/main/scala/org/scalaexercises/evaluator/codecs.scala
+++ b/server/src/main/scala/org/scalaexercises/evaluator/codecs.scala
@@ -1,40 +1,23 @@
 /*
- * scala-exercises - evaluator-server
- * Copyright (C) 2015-2016 47 Degrees, LLC. <http://www.47deg.com>
+ *
+ *  scala-exercises - evaluator-server
+ *  Copyright (C) 2015-2019 47 Degrees, LLC. <http://www.47deg.com>
+ *
  */
 
 package org.scalaexercises.evaluator
 
-import org.http4s._, org.http4s.dsl._
-import io.circe.{Decoder, Encoder, Json, Printer}
-import org.http4s.headers.`Content-Type`
-import io.circe.jawn.CirceSupportParser.facade
+import cats.effect.Sync
+import io.circe.{Decoder, Encoder}
+import org.http4s._
+import org.http4s.circe._
 
 /** Provides Json serialization codecs for the http4s services */
 trait Http4sCodecInstances {
 
-  implicit val jsonDecoder: EntityDecoder[Json] = jawn.jawnDecoder(facade)
+  implicit def entityDecoderOf[F[_]: Sync, A: Decoder]: EntityDecoder[F, A] = jsonOf[F, A]
 
-  implicit def jsonDecoderOf[A](implicit decoder: Decoder[A]): EntityDecoder[A] =
-    jsonDecoder.flatMapR { json =>
-      decoder
-        .decodeJson(json)
-        .fold(
-          failure =>
-            DecodeResult.failure(
-              InvalidMessageBodyFailure(s"Could not decode JSON: $json", Some(failure))),
-          DecodeResult.success(_)
-        )
-    }
-
-  implicit val jsonEntityEncoder: EntityEncoder[Json] = EntityEncoder[String]
-    .contramap[Json] { json =>
-      Printer.noSpaces.pretty(json)
-    }
-    .withContentType(`Content-Type`(MediaType.`application/json`))
-
-  implicit def jsonEncoderOf[A](implicit encoder: Encoder[A]): EntityEncoder[A] =
-    jsonEntityEncoder.contramap[A](encoder.apply)
+  implicit def entityEncoderOf[F[_]: Sync, A: Encoder]: EntityEncoder[F, A] = jsonEncoderOf[F, A]
 
 }
 
diff --git a/server/src/main/scala/org/scalaexercises/evaluator/evaluation.scala b/server/src/main/scala/org/scalaexercises/evaluator/evaluation.scala
index 38408d03..40792151 100644
--- a/server/src/main/scala/org/scalaexercises/evaluator/evaluation.scala
+++ b/server/src/main/scala/org/scalaexercises/evaluator/evaluation.scala
@@ -1,6 +1,8 @@
 /*
- * scala-exercises - evaluator-server
- * Copyright (C) 2015-2016 47 Degrees, LLC. <http://www.47deg.com>
+ *
+ *  scala-exercises - evaluator-server
+ *  Copyright (C) 2015-2019 47 Degrees, LLC. <http://www.47deg.com>
+ *
  */
 
 package org.scalaexercises.evaluator
@@ -9,11 +11,13 @@ import java.io.{ByteArrayOutputStream, File}
 import java.math.BigInteger
 import java.net.URLClassLoader
 import java.security.MessageDigest
-import java.util.concurrent.TimeoutException
 import java.util.jar.JarFile
 
+import cats.effect.{Concurrent, ConcurrentEffect, ContextShift, Timer}
+import cats.implicits._
 import coursier._
-import monix.execution.Scheduler
+import coursier.cache.{ArtifactError, FileCache}
+import coursier.util.Sync
 import org.scalaexercises.evaluator.Eval.CompilerException
 
 import scala.concurrent.duration._
@@ -24,13 +28,11 @@ import scala.tools.nsc.reporters._
 import scala.tools.nsc.{Global, Settings}
 import scala.util.Try
 import scala.util.control.NonFatal
-import scalaz.Scalaz._
-import scalaz._
-import scalaz.concurrent.Task
 
-class Evaluator(timeout: FiniteDuration = 20.seconds)(
-    implicit S: Scheduler
-) {
+class Evaluator[F[_]: Sync](timeout: FiniteDuration = 20.seconds)(
+    implicit CS: ContextShift[F],
+    F: ConcurrentEffect[F],
+    T: Timer[F]) {
   type Remote = String
 
   private[this] def convert(errors: (Position, String, String)): (String, List[CompilationInfo]) = {
@@ -38,31 +40,35 @@ class Evaluator(timeout: FiniteDuration = 20.seconds)(
     (severity, CompilationInfo(msg, Some(RangePosition(pos.start, pos.point, pos.end))) :: Nil)
   }
 
-  def remoteToRepository(remote: Remote): Repository =
-    MavenRepository(remote)
+  def remoteToRepository(remote: Remote): Repository = MavenRepository(remote)
 
   def dependencyToModule(dependency: Dependency): coursier.Dependency =
-    coursier.Dependency(
-      Module(dependency.groupId, dependency.artifactId),
+    coursier.Dependency.of(
+      Module(Organization(dependency.groupId), ModuleName(dependency.artifactId)),
       dependency.version
     )
 
-  def resolveArtifacts(remotes: Seq[Remote], dependencies: Seq[Dependency]): Task[Resolution] = {
-    val resolution                    = Resolution(dependencies.map(dependencyToModule).toSet)
-    val repositories: Seq[Repository] = Cache.ivy2Local +: remotes.map(remoteToRepository)
-    val fetch                         = Fetch.from(repositories, Cache.fetch())
-    resolution.process.run(fetch)
+  val cache: FileCache[F] = FileCache[F].noCredentials
+
+  def resolveArtifacts(remotes: Seq[Remote], dependencies: Seq[Dependency]): F[Resolution] = {
+    Resolve[F](cache)
+      .addDependencies(dependencies.map(dependencyToModule): _*)
+      .addRepositories(remotes.map(remoteToRepository): _*)
+      .addRepositories(coursier.LocalRepositories.ivy2Local)
+      .io
   }
 
   def fetchArtifacts(
       remotes: Seq[Remote],
-      dependencies: Seq[Dependency]): Task[coursier.FileError \/ List[File]] =
+      dependencies: Seq[Dependency]): F[Either[ArtifactError, List[File]]] =
     for {
-      resolution <- resolveArtifacts(remotes, dependencies)
-      artifacts <- Task.gatherUnordered(
-        resolution.artifacts.map(Cache.file(_).run)
-      )
-    } yield artifacts.sequenceU
+      resolution        <- resolveArtifacts(remotes, dependencies)
+      gatheredArtifacts <- resolution.artifacts().toList.traverse(cache.file(_).run)
+      artifacts = gatheredArtifacts.foldRight(Right(Nil): Either[ArtifactError, List[File]]) {
+        case (Right(file), acc) => acc.map(file :: _)
+        case (Left(ae), _)      => Left(ae)
+      }
+    } yield artifacts
 
   def createEval(jars: Seq[File]) = {
     new Eval(jars = jars.toList) {
@@ -124,22 +130,29 @@ class Evaluator(timeout: FiniteDuration = 20.seconds)(
       code: String,
       remotes: Seq[Remote] = Nil,
       dependencies: Seq[Dependency] = Nil
-  ): Task[EvalResult[T]] = {
+  ): F[EvalResult[T]] = {
     for {
       allJars <- fetchArtifacts(remotes, dependencies)
       result <- allJars match {
-        case \/-(jars) =>
-          Task({
-            evaluate(code, jars)
-          }).timed(timeout)
-            .handle({
-              case err: TimeoutException => Timeout[T](timeout)
-            })
-        case -\/(fileError) =>
-          Task.now(UnresolvedDependency(fileError.describe))
+        case Right(jars) =>
+          val fallback: EvalResult[T] = Timeout[T](timeout)
+          val success: F[EvalResult[T]] =
+            timeoutTo(F.delay { evaluate(code, jars) }, timeout, fallback)
+          success
+        case Left(fileError) =>
+          val failure: F[EvalResult[T]] = F.pure(UnresolvedDependency[T](fileError.describe))
+          failure
       }
     } yield result
   }
+
+  def timeoutTo[A](fa: F[A], after: FiniteDuration, fallback: A): F[A] = {
+
+    Concurrent[F].race(fa, T.sleep(after)).flatMap {
+      case Left(a)  => a.pure[F]
+      case Right(_) => fallback.pure[F]
+    }
+  }
 }
 
 /**
@@ -170,7 +183,7 @@ private class StringCompiler(
     val settings = StringCompiler.this.settings
     val messages = new scala.collection.mutable.ListBuffer[List[String]]
 
-    def display(pos: Position, message: String, severity: Severity) {
+    def display(pos: Position, message: String, severity: Severity) = {
       severity.count += 1
       val severityName = severity match {
         case ERROR   => "error: "
@@ -193,11 +206,11 @@ private class StringCompiler(
        })
     }
 
-    def displayPrompt {
+    def displayPrompt = {
       // no.
     }
 
-    override def reset {
+    override def reset = {
       super.reset
       messages.clear()
     }
@@ -205,7 +218,7 @@ private class StringCompiler(
 
   val global = new Global(settings, reporter)
 
-  def reset() {
+  def reset() = {
     targetDir match {
       case None => {
         output.asInstanceOf[VirtualDirectory].clear()
@@ -239,7 +252,7 @@ private class StringCompiler(
   /**
    * Compile scala code. It can be found using the above class loader.
    */
-  def apply(code: String) {
+  def apply(code: String) = {
     // if you're looking for the performance hit, it's 1/2 this line...
     val compiler    = new global.Run
     val sourceFiles = List(new BatchSourceFile("(inline)", code))
@@ -366,7 +379,7 @@ class Eval(target: Option[File] = None, jars: List[File] = Nil) {
    * Check if code is Eval-able.
    * @throws CompilerException if not Eval-able.
    */
-  def check(code: String) {
+  def check(code: String) = {
     val id          = uniqueId(code)
     val className   = "Evaluator__" + id
     val wrappedCode = wrapCodeInClass(className, code)
diff --git a/server/src/main/scala/org/scalaexercises/evaluator/services.scala b/server/src/main/scala/org/scalaexercises/evaluator/services.scala
index aa5dfe8f..c0ba6a35 100644
--- a/server/src/main/scala/org/scalaexercises/evaluator/services.scala
+++ b/server/src/main/scala/org/scalaexercises/evaluator/services.scala
@@ -1,15 +1,25 @@
 /*
- * scala-exercises - evaluator-server
- * Copyright (C) 2015-2016 47 Degrees, LLC. <http://www.47deg.com>
+ *
+ *  scala-exercises - evaluator-server
+ *  Copyright (C) 2015-2019 47 Degrees, LLC. <http://www.47deg.com>
+ *
  */
 
 package org.scalaexercises.evaluator
 
-import monix.execution.Scheduler
+import cats.effect.{ConcurrentEffect, ContextShift, ExitCode, IO, IOApp, Timer}
+import cats.implicits._
+import codecs._
+import coursier.util.Sync
+import coursier.interop.cats._
+import io.circe.generic.auto._
+import io.circe.syntax._
 import org.http4s._
 import org.http4s.dsl._
+import org.http4s.headers.Allow
 import org.http4s.server.blaze._
 import org.log4s.getLogger
+import org.http4s.syntax.kleisli.http4sKleisliResponseSyntax
 
 import scala.concurrent.duration._
 import scala.language.postfixOps
@@ -17,14 +27,8 @@ import scala.language.postfixOps
 object services {
 
   import EvalResponse.messages._
-  import codecs._
-  import io.circe.generic.auto._
 
-  private val logger = getLogger
-
-  implicit val scheduler: Scheduler = Scheduler.io("scala-evaluator")
-
-  val evaluator = new Evaluator(20 seconds)
+  def evaluatorInstance[F[_]: ConcurrentEffect: ContextShift: Timer: Sync] = new Evaluator[F](20 seconds)
 
   val corsHeaders = Seq(
     Header("Vary", "Origin,Access-Control-Request-Methods"),
@@ -34,95 +38,87 @@ object services {
     Header("Access-Control-Max-Age", 1.day.toSeconds.toString())
   )
 
-  def evalService =
-    auth(HttpService {
-      case req @ POST -> Root / "eval" =>
-        import io.circe.syntax._
-        req
-          .decode[EvalRequest] {
-            evalRequest =>
-              evaluator.eval[Any](
-                code = evalRequest.code,
-                remotes = evalRequest.resolvers,
-                dependencies = evalRequest.dependencies
-              ) flatMap {
-                (result: EvalResult[_]) =>
-                  val response = result match {
-                    case EvalSuccess(cis, res, out) =>
-                      EvalResponse(
-                        `ok`,
-                        Option(res.toString),
-                        Option(res.asInstanceOf[AnyRef].getClass.getName),
-                        Option(out),
-                        cis)
-                    case Timeout(_) =>
-                      EvalResponse(`Timeout Exceded`, None, None, None, Map.empty)
-                    case UnresolvedDependency(msg) =>
-                      EvalResponse(
-                        `Unresolved Dependency` + " : " + msg,
-                        None,
-                        None,
-                        None,
-                        Map.empty)
-                    case EvalRuntimeError(cis, runtimeError) =>
-                      EvalResponse(
-                        `Runtime Error`,
-                        runtimeError map (_.error.getMessage),
-                        runtimeError map (_.error.getClass.getName),
-                        None,
-                        cis)
-                    case CompilationError(cis) =>
-                      EvalResponse(`Compilation Error`, None, None, None, cis)
-                    case GeneralError(err) =>
-                      EvalResponse(`Unforeseen Exception`, None, None, None, Map.empty)
+  def service[F[_]: ConcurrentEffect: ContextShift: Timer: Sync] = new Http4sDsl[F] {
+    def httpApp(evaluator: Evaluator[F]) =
+      HttpRoutes
+        .of[F] {
+          // Evaluator service
+          case req @ POST -> Root / "eval" =>
+            req
+              .decode[EvalRequest] { evalRequest =>
+                evaluator
+                  .eval[Any](
+                    code = evalRequest.code,
+                    remotes = evalRequest.resolvers,
+                    dependencies = evalRequest.dependencies
+                  )
+                  .flatMap { (result: EvalResult[_]) =>
+                    val response = result match {
+                      case EvalSuccess(cis, res, out) =>
+                        EvalResponse(
+                          `ok`,
+                          Option(res.toString),
+                          Option(res.asInstanceOf[AnyRef].getClass.getName),
+                          Option(out),
+                          cis)
+                      case Timeout(_) =>
+                        EvalResponse(`Timeout Exceded`, None, None, None, Map.empty)
+                      case UnresolvedDependency(msg) =>
+                        EvalResponse(
+                          `Unresolved Dependency` + " : " + msg,
+                          None,
+                          None,
+                          None,
+                          Map.empty)
+                      case EvalRuntimeError(cis, runtimeError) =>
+                        EvalResponse(
+                          `Runtime Error`,
+                          runtimeError map (_.error.getMessage),
+                          runtimeError map (_.error.getClass.getName),
+                          None,
+                          cis)
+                      case CompilationError(cis) =>
+                        EvalResponse(`Compilation Error`, None, None, None, cis)
+                      case GeneralError(err) =>
+                        EvalResponse(`Unforeseen Exception`, None, None, None, Map.empty)
+                    }
+                    Ok(response.asJson)
                   }
-                  Ok(response.asJson)
               }
-          }
-          .map((r: Response) => r.putHeaders(corsHeaders: _*))
-    })
-
-  def loaderIOService = HttpService {
-
-    case _ -> Root =>
-      MethodNotAllowed()
-
-    case GET -> Root / "loaderio-1318d1b3e06b7bc96dd5de5716f57496" =>
-      Ok("loaderio-1318d1b3e06b7bc96dd5de5716f57496")
-  }
-
-  // CORS middleware in http4s can't be combined with our `auth` middleware. We need to handle CORS calls ourselves.
-  def optionsService = HttpService {
-    case OPTIONS -> Root / "eval" =>
-      Ok().putHeaders(corsHeaders: _*)
+              .map((r: Response[F]) => r.putHeaders(corsHeaders: _*))
+          // LoaderIO service
+          case _ -> Root => MethodNotAllowed(Allow(GET, POST, OPTIONS))
+          case GET -> Root / "loaderio-1318d1b3e06b7bc96dd5de5716f57496" =>
+            Ok("loaderio-1318d1b3e06b7bc96dd5de5716f57496")
+          // Options service
+          // CORS middleware in http4s can't be combined with our `auth` middleware. We need to handle CORS calls ourselves.
+          case OPTIONS -> Root / "eval" =>
+            Ok().map(res => res.withHeaders(corsHeaders: _*)) //putHeaders(corsHeaders: _*)
+        }
+        .orNotFound
   }
 
 }
 
-object EvaluatorServer extends App {
+object EvaluatorServer extends IOApp {
 
   import services._
 
   private[this] val logger = getLogger
 
-  val ip = Option(System.getenv("HOST")).getOrElse("0.0.0.0")
+  lazy val ip = Option(System.getenv("HOST")).getOrElse("0.0.0.0")
 
-  val port = (Option(System.getenv("PORT")) orElse
+  lazy val port = (Option(System.getenv("PORT")) orElse
     Option(System.getProperty("http.port"))).map(_.toInt).getOrElse(8080)
 
-  logger.info(s"Initializing Evaluator at $ip:$port")
-
-  // The order in which services are mounted is really important. They're executed from bottom to top, and they won't be
-  // checked for repeated methods or routes. That's why we set the `optionsService` before the `evalService` one, as if
-  // not, execution of a OPTIONS call to /eval would lead to `evalService`, even if that service doesn't recognize the
-  // OPTIONS verb.
-  BlazeBuilder
-    .bindHttp(port, ip)
-    .mountService(evalService)
-    .mountService(optionsService)
-    .mountService(loaderIOService)
-    .start
-    .run
-    .awaitShutdown()
+  override def run(args: List[String]): IO[ExitCode] = {
+    logger.info(s"Initializing Evaluator at $ip:$port")
 
+    BlazeServerBuilder[IO]
+      .bindHttp(port, ip)
+      .withHttpApp(auth[IO](service[IO].httpApp(evaluatorInstance[IO])))
+      .serve
+      .compile
+      .lastOrError
+  }
 }
diff --git a/shared/shared/src/main/scala/org/scalaexercises/evaluator/types.scala b/shared/src/main/scala/org/scalaexercises/evaluator/types.scala
similarity index 93%
rename from shared/shared/src/main/scala/org/scalaexercises/evaluator/types.scala
rename to shared/src/main/scala/org/scalaexercises/evaluator/types.scala
index 81d8046d..fe793f71 100644
--- a/shared/shared/src/main/scala/org/scalaexercises/evaluator/types.scala
+++ b/shared/src/main/scala/org/scalaexercises/evaluator/types.scala
@@ -1,6 +1,8 @@
 /*
- * scala-exercises - evaluator-shared
- * Copyright (C) 2015-2016 47 Degrees, LLC. <http://www.47deg.com>
+ *
+ *  scala-exercises - evaluator-shared
+ *  Copyright (C) 2015-2019 47 Degrees, LLC. <http://www.47deg.com>
+ *
  */
 
 package org.scalaexercises.evaluator