diff --git a/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockPoolActor.scala b/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockPoolActor.scala
index 0776c48..8944a44 100644
--- a/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockPoolActor.scala
+++ b/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockPoolActor.scala
@@ -7,7 +7,6 @@ import com.github.fluency03.blockchain.api._
 import com.github.fluency03.blockchain.core.Block
 
 import scala.collection.mutable
-import scala.concurrent.Future
 import scala.util.{Failure, Success}
 
 object BlockPoolActor {
@@ -33,7 +32,7 @@ class BlockPoolActor extends ActorSupport {
   val txPoolActor: ActorSelection = context.actorSelection(PARENT_UP + TX_POOL_ACTOR_NAME)
 
   // TODO (Chang): need persistence
-  var blocksPool = mutable.Map.empty[String, Block]
+  var blocksPool: mutable.Map[String, Block] = mutable.Map.empty[String, Block]
 
   def receive: Receive = {
     case GetBlocks => onGetBlocks()
@@ -49,12 +48,10 @@ class BlockPoolActor extends ActorSupport {
   /**
    * Handlers for each of the Messages.
    */
-
   private[this] def onGetBlocks(): Unit = sender() ! blocksPool.values.toSeq
 
-  private[this] def onGetBlocks(hashes: Set[String]): Unit = sender() ! blocksPool.filterKeys(
-    k => hashes.contains(k)
-  ).values.toSeq
+  private[this] def onGetBlocks(hashes: Set[String]): Unit =
+    sender() ! blocksPool.filterKeys(hashes.contains).values.toSeq
 
   private[this] def onAddBlock(block: Block): Unit = {
     if (blocksPool.contains(block.hash))
@@ -79,18 +76,18 @@ class BlockPoolActor extends ActorSupport {
   }
 
   private def onMineAndAddNextBlock(data: String, ids: Seq[String]): Unit = {
-    val maybeBlock: Future[Option[Block]] =
-      (blockchainActor ? BlockchainActor.MineNextBlock(data, ids)).mapTo[Option[Block]]
     val theSender: ActorRef = sender()
-    maybeBlock onComplete {
-      case Success(blockOpt) => blockOpt match {
-        case Some(block) =>
-          blocksPool += (block.hash -> block)
-          theSender ! Some(block)
-        case None => theSender ! None
+    (blockchainActor ? BlockchainActor.MineNextBlock(data, ids))
+      .mapTo[Option[Block]]
+      .onComplete {
+        case Success(blockOpt) => blockOpt match {
+          case Some(block) =>
+            blocksPool += (block.hash -> block)
+            theSender ! Some(block)
+          case None => theSender ! None
+        }
+        case Failure(_) => theSender ! None
       }
-      case Failure(_) => theSender ! None
-    }
   }
 
 
diff --git a/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockchainActor.scala b/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockchainActor.scala
index 4bd9c3b..e4f0af6 100644
--- a/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockchainActor.scala
+++ b/src/main/scala/com/github/fluency03/blockchain/api/actors/BlockchainActor.scala
@@ -74,7 +74,6 @@ class BlockchainActor extends ActorSupport {
   /**
    * Handlers for each of the BlockchainMsg.
    */
-
   private def onGetBlockchain(): Unit = sender() ! blockchainOpt
 
   private def onCreateBlockchain(): Unit = blockchainOpt match {
@@ -97,9 +96,7 @@ class BlockchainActor extends ActorSupport {
   }
 
   private def onCheckBlockchainValidity(): Unit = blockchainOpt match {
-    case Some(blockchain) => sender() ! {
-      if (blockchain.isValid) SuccessMsg("true") else SuccessMsg("false")
-    }
+    case Some(blockchain) => sender() ! SuccessMsg(blockchain.isValid.toString)
     case None =>
       clearMappingOnNoBlockchain()
       sender() ! FailureMsg("Blockchain does not exist.")
@@ -108,7 +105,6 @@ class BlockchainActor extends ActorSupport {
   /**
    * Handlers for each of the BlockMsg.
    */
-
   private def onGetBlockByHash(hash: String): Unit = sender() ! getBlockByHash(hash)
 
   private def onGetBlocksByHashesAndIndices(hashes: Set[String], indices: Set[Int]): Unit =
@@ -144,7 +140,7 @@ class BlockchainActor extends ActorSupport {
           case Success(blockOpt) => blockOpt match {
             case Some(block) =>
               appendBlock(block, blockchain)
-              sender ! SuccessMsg(s"New Block ${block.hash} added on the chain.")
+              theSender ! SuccessMsg(s"New Block ${block.hash} added on the chain.")
             case None => theSender ! FailureMsg(s"Did not find Block $hash in the poll.")
           }
           case Failure(e) =>
@@ -186,7 +182,9 @@ class BlockchainActor extends ActorSupport {
   private def onGetBlockFromPool(hash: String): Unit =
     blockPoolActor forward BlockPoolActor.GetBlock(hash)
 
-
+  /**
+   * Private helper methods.
+   */
   private def getBlockByHash(hash: String): Option[Block] = hashIndexMapping.get(hash) match {
     case Some(index) => blockchainOpt match {
       case Some(blockchain) => Some(blockchain.chain(index))
@@ -211,5 +209,4 @@ class BlockchainActor extends ActorSupport {
     hashIndexMapping.clear()
   }
 
-
 }
diff --git a/src/main/scala/com/github/fluency03/blockchain/api/actors/NetworkActor.scala b/src/main/scala/com/github/fluency03/blockchain/api/actors/NetworkActor.scala
index d5dccec..3fd3a19 100644
--- a/src/main/scala/com/github/fluency03/blockchain/api/actors/NetworkActor.scala
+++ b/src/main/scala/com/github/fluency03/blockchain/api/actors/NetworkActor.scala
@@ -52,37 +52,42 @@ class NetworkActor extends ActorSupport {
   /**
    * Handlers for each of the Messages.
    */
-
   private def onGetNetwork(): Unit = sender() ! context.children.map(_.path.name).toSet
 
-  private def onGetPeers(): Unit = Future.sequence(context.children.map(p => {
-    (p ? GetPublicKeys).mapTo[Set[String]].map(keys => p.path.name -> keys)
-  })).map(_.toMap).pipeTo(sender())
+  private def onGetPeers(): Unit = {
+    val peers = context.children.map { p =>
+      (p ? GetPublicKeys).mapTo[Set[String]].map(keys => p.path.name -> keys)
+    }
+    Future.sequence(peers).map(_.toMap).pipeTo(sender())
+  }
 
-  private def onGetPeers(names: Set[String]): Unit = Future.sequence(context.children
-    .filter(p => names.contains(p.path.name))
-    .map(p => { (p ? GetPublicKeys).mapTo[Set[String]].map(keys => p.path.name -> keys) })
-  ).map(_.toMap).pipeTo(sender())
+  private def onGetPeers(names: Set[String]): Unit = {
+    val peers = context.children
+      .filter { p => names.contains(p.path.name) }
+      .map { p => (p ? GetPublicKeys).mapTo[Set[String]].map(keys => p.path.name -> keys) }
+    Future.sequence(peers).map(_.toMap).pipeTo(sender())
+  }
 
-  private def onCreatePeer(name: String): Unit =
-    if (context.child(name).isDefined) sender() ! FailureMsg(s"Peer $name has been created.")
-    else {
+  private def onCreatePeer(name: String): Unit = context.child(name) match {
+    case Some(_) => sender() ! FailureMsg(s"Peer $name has been created.")
+    case None =>
       val _ = context.actorOf(Props[PeerActor], name)
       sender() ! SuccessMsg(s"Peer $name created.")
-    }
+  }
 
-  private def onGetPeer(name: String): Unit =
-    if (context.child(name).isDefined) {
-      (context.child(name).get ? GetPublicKeys)
-        .mapTo[Set[String]]
-        .map(keys => Some(Peer(name, keys)))
-        .pipeTo(sender())
-    } else sender() ! None
+  private def onGetPeer(name: String): Unit = context.child(name) match {
+    case Some(_) => (context.child(name).get ? GetPublicKeys)
+      .mapTo[Set[String]]
+      .map { keys => Some(Peer(name, keys)) }
+      .pipeTo(sender())
+    case None => sender() ! None
+  }
 
-  private def onDeletePeer(name: String): Unit =
-    if (context.child(name).isDefined) {
+  private def onDeletePeer(name: String): Unit = context.child(name) match {
+    case Some(_) =>
       context stop context.child(name).get
       sender() ! SuccessMsg(s"Peer $name deleted.")
-    } else sender() ! FailureMsg(s"Peer $name does not exist.")
+    case None => sender() ! FailureMsg(s"Peer $name does not exist.")
+  }
 
 }
diff --git a/src/main/scala/com/github/fluency03/blockchain/api/actors/PeerActor.scala b/src/main/scala/com/github/fluency03/blockchain/api/actors/PeerActor.scala
index 8a691a5..817d0a7 100644
--- a/src/main/scala/com/github/fluency03/blockchain/api/actors/PeerActor.scala
+++ b/src/main/scala/com/github/fluency03/blockchain/api/actors/PeerActor.scala
@@ -22,8 +22,8 @@ class PeerActor extends ActorSupport {
   override def postStop(): Unit = log.info("{} stopped!", this.getClass.getSimpleName)
 
   // TODO (Chang): need persistence
-  val wallet = mutable.Map.empty[String, KeyContainer]
-  val others = mutable.Map.empty[String, Peer]
+  val wallet: mutable.Map[String, KeyContainer] = mutable.Map.empty[String, KeyContainer]
+  val others: mutable.Map[String, Peer] = mutable.Map.empty[String, Peer]
 
   /**
    * TODO (Chang):
diff --git a/src/main/scala/com/github/fluency03/blockchain/api/actors/TxPoolActor.scala b/src/main/scala/com/github/fluency03/blockchain/api/actors/TxPoolActor.scala
index d019212..86aa3be 100644
--- a/src/main/scala/com/github/fluency03/blockchain/api/actors/TxPoolActor.scala
+++ b/src/main/scala/com/github/fluency03/blockchain/api/actors/TxPoolActor.scala
@@ -49,7 +49,6 @@ class TxPoolActor extends ActorSupport {
   /**
    * Handlers for each of the Messages.
    */
-
   private def onGetTransactions(): Unit = sender() ! transPool.values.toSeq
 
   private def onGetTransactions(ids: Seq[String]): Unit =