diff --git a/README.md b/README.md
index e11543bc..4e53f7ce 100644
--- a/README.md
+++ b/README.md
@@ -609,7 +609,7 @@ println(s"After set: ${myVar.now()}")
 myVar.update(_ + 1)
 println(s"After update: ${myVar.now()}")
 
-Transaction {
+Transaction { _ =>
   println(s"After trx: ${myVar.now()}")
 }
 
diff --git a/src/main/scala/com/raquo/airstream/combine/MergeStream.scala b/src/main/scala/com/raquo/airstream/combine/MergeStream.scala
index 24388837..c48dcf4f 100644
--- a/src/main/scala/com/raquo/airstream/combine/MergeStream.scala
+++ b/src/main/scala/com/raquo/airstream/combine/MergeStream.scala
@@ -55,8 +55,8 @@ class MergeStream[A](
       if (lastFiredInTrx.contains(transaction)) {
         //println("- syncFire in new trx")
         nextValue.fold(
-          nextError => new Transaction(fireError(nextError, _)),
-          nextEvent => new Transaction(fireValue(nextEvent, _))
+          nextError => Transaction(fireError(nextError, _)),
+          nextEvent => Transaction(fireValue(nextEvent, _))
         )
       } else {
         lastFiredInTrx = transaction
diff --git a/src/main/scala/com/raquo/airstream/core/Transaction.scala b/src/main/scala/com/raquo/airstream/core/Transaction.scala
index f47475a8..74714ba1 100644
--- a/src/main/scala/com/raquo/airstream/core/Transaction.scala
+++ b/src/main/scala/com/raquo/airstream/core/Transaction.scala
@@ -59,15 +59,14 @@ class Transaction(private[Transaction] var code: Transaction => Any) {
 
 object Transaction {
 
-  /** Create new transaction (typically used in internal observable code) */
-  def apply(code: Transaction => Unit): Unit = new Transaction(code)
-
-  /** Create new transaction (typically used in end user code).
+  /** Create new transaction.
     *
-    * Warning: It is rare that you need to manually create transactions.
+    * Typically used in internal observable code.
+    *
+    * Warning: It is rare that end users need to manually create transactions.
     * Example of legitimate use case: [[https://github.com/raquo/Airstream/#var-transaction-delay Var transaction delay]]
     */
-  def apply(code: => Unit): Unit = new Transaction(_ => code)
+  def apply(code: Transaction => Unit): Unit = new Transaction(code)
 
   /** This object holds a queue of callbacks that should be executed
     * when all observables finish starting. This lets `signal.changes`
@@ -158,7 +157,7 @@ object Transaction {
         //println("- no pending callbacks")
         if (postStartTransactions.length > 0) {
           //println(s"> CREATE ALT RESOLVE TRX. Num trx-s = ${postStartTransactions.length}")
-          Transaction {
+          Transaction { _ =>
             while (postStartTransactions.length > 0) {
               pendingTransactions.add(postStartTransactions.shift())
             }
diff --git a/src/main/scala/com/raquo/airstream/custom/CustomSignalSource.scala b/src/main/scala/com/raquo/airstream/custom/CustomSignalSource.scala
index ec7fb0e3..1bae74f3 100644
--- a/src/main/scala/com/raquo/airstream/custom/CustomSignalSource.scala
+++ b/src/main/scala/com/raquo/airstream/custom/CustomSignalSource.scala
@@ -17,7 +17,7 @@ class CustomSignalSource[A] (
 ) extends WritableSignal[A] with CustomSource[A] {
 
   override protected[this] val config: Config = makeConfig(
-    value => new Transaction(fireTry(value, _)),
+    value => Transaction(fireTry(value, _)),
     () => tryNow(),
     () => startIndex,
     () => isStarted
diff --git a/src/main/scala/com/raquo/airstream/custom/CustomSource.scala b/src/main/scala/com/raquo/airstream/custom/CustomSource.scala
index caa7deb1..e634db2a 100644
--- a/src/main/scala/com/raquo/airstream/custom/CustomSource.scala
+++ b/src/main/scala/com/raquo/airstream/custom/CustomSource.scala
@@ -31,7 +31,7 @@ trait CustomSource[A] extends WritableObservable[A] {
 
   override protected[this] def onStart(): Unit = {
     Try(config.onStart()).recover[Unit] {
-      case err: Throwable => new Transaction(fireError(err, _))
+      case err: Throwable => Transaction(fireError(err, _))
     }
     super.onStart()
   }
diff --git a/src/main/scala/com/raquo/airstream/custom/CustomStreamSource.scala b/src/main/scala/com/raquo/airstream/custom/CustomStreamSource.scala
index dffe2d08..c5bd4105 100644
--- a/src/main/scala/com/raquo/airstream/custom/CustomStreamSource.scala
+++ b/src/main/scala/com/raquo/airstream/custom/CustomStreamSource.scala
@@ -12,12 +12,8 @@ class CustomStreamSource[A] (
 ) extends WritableStream[A] with CustomSource[A] {
 
   override protected[this] val config: Config = makeConfig(
-    value => {
-      new Transaction(fireValue(value, _))
-    },
-    err => {
-      new Transaction(fireError(err, _))
-    },
+    value => Transaction(fireValue(value, _)),
+    err => Transaction(fireError(err, _)),
     () => startIndex,
     () => isStarted
   )
diff --git a/src/main/scala/com/raquo/airstream/eventbus/EventBusStream.scala b/src/main/scala/com/raquo/airstream/eventbus/EventBusStream.scala
index 09a630ca..49434144 100644
--- a/src/main/scala/com/raquo/airstream/eventbus/EventBusStream.scala
+++ b/src/main/scala/com/raquo/airstream/eventbus/EventBusStream.scala
@@ -41,7 +41,7 @@ class EventBusStream[A] private[eventbus] () extends WritableStream[A] with Inte
 
     //println(s"> init trx from EventBusStream(${nextValue})")
 
-    new Transaction(fireValue(nextValue, _))
+    Transaction(fireValue(nextValue, _))
   }
 
   /** Helper method to support batch emit using `WriteBus.emit` / `WriteBus.emitTry` */
@@ -55,7 +55,7 @@ class EventBusStream[A] private[eventbus] () extends WritableStream[A] with Inte
   }
 
   override protected def onError(nextError: Throwable, transaction: Transaction): Unit = {
-    new Transaction(fireError(nextError, _))
+    Transaction(fireError(nextError, _))
   }
 
   override protected def onWillStart(): Unit = {
diff --git a/src/main/scala/com/raquo/airstream/eventbus/WriteBus.scala b/src/main/scala/com/raquo/airstream/eventbus/WriteBus.scala
index 972a91ca..757629c5 100644
--- a/src/main/scala/com/raquo/airstream/eventbus/WriteBus.scala
+++ b/src/main/scala/com/raquo/airstream/eventbus/WriteBus.scala
@@ -96,7 +96,7 @@ object WriteBus {
     if (hasDuplicateTupleKeys(values.map(_.tuple))) {
       throw new Exception("Unable to {EventBus,WriteBus}.emit: the provided list of event buses has duplicates. You can't make an observable emit more than one event per transaction.")
     }
-    new Transaction(trx => values.foreach(emitValue(_, trx)))
+    Transaction(trx => values.foreach(emitValue(_, trx)))
   }
 
   /** Emit events into several WriteBus-es at once (in the same transaction)
@@ -107,7 +107,7 @@ object WriteBus {
     if (hasDuplicateTupleKeys(values.map(_.tuple))) {
       throw new Exception("Unable to {EventBus,WriteBus}.emitTry: the provided list of event buses has duplicates. You can't make an observable emit more than one event per transaction.")
     }
-    new Transaction(trx => values.foreach(emitTryValue(_, trx)))
+    Transaction(trx => values.foreach(emitTryValue(_, trx)))
   }
 
   @inline private def emitValue[A](tuple: BusTuple[A], transaction: Transaction): Unit = {
diff --git a/src/main/scala/com/raquo/airstream/flatten/ConcurrentStream.scala b/src/main/scala/com/raquo/airstream/flatten/ConcurrentStream.scala
index 7ad212b8..ba4259c1 100644
--- a/src/main/scala/com/raquo/airstream/flatten/ConcurrentStream.scala
+++ b/src/main/scala/com/raquo/airstream/flatten/ConcurrentStream.scala
@@ -20,8 +20,8 @@ class ConcurrentStream[A](
   private val accumulatedStreams: JsArray[EventStream[A]] = JsArray()
 
   private val internalEventObserver: InternalObserver[A] = InternalObserver[A](
-    onNext = (nextEvent, _) => new Transaction(fireValue(nextEvent, _)),
-    onError = (nextError, _) => new Transaction(fireError(nextError, _))
+    onNext = (nextEvent, _) => Transaction(fireValue(nextEvent, _)),
+    onError = (nextError, _) => Transaction(fireError(nextError, _))
   )
 
   override protected val topoRank: Int = 1
@@ -51,7 +51,7 @@ class ConcurrentStream[A](
           case Failure(err) =>
             // @TODO[API] Not 100% sure that we should emit this error, but since
             //  we expect to use signal's current value, I think this is right.
-            new Transaction(fireError(err, _)) // #Note[onStart,trx,loop]
+            Transaction(fireError(err, _)) // #Note[onStart,trx,loop]
           case _ => ()
         }
       case _ => ()
diff --git a/src/main/scala/com/raquo/airstream/flatten/SwitchSignal.scala b/src/main/scala/com/raquo/airstream/flatten/SwitchSignal.scala
index be8dbbe1..8f691356 100644
--- a/src/main/scala/com/raquo/airstream/flatten/SwitchSignal.scala
+++ b/src/main/scala/com/raquo/airstream/flatten/SwitchSignal.scala
@@ -30,7 +30,7 @@ class SwitchSignal[A](
     onTry = (nextTry, _) => {
       //println(s"> init trx from $this SwitchSignal.onValue($nextTry)")
       innerSignalLastSeenUpdateId = Protected.lastUpdateId(currentSignalTry.get)
-      new Transaction(fireTry(nextTry, _))
+      Transaction(fireTry(nextTry, _))
     }
   )
 
@@ -104,7 +104,7 @@ class SwitchSignal[A](
       // Update this signal's value with nextSignal's current value (or an error if we don't have nextSignal)
 
       //println(s"> init trx from SwitchSignal.onTry (new signal)")
-      new Transaction(trx => {
+      Transaction { trx =>
 
         // #Note: Timing is important here.
         // 1. Create the `trx` transaction, since we need that boundary when flattening
@@ -130,7 +130,7 @@ class SwitchSignal[A](
 
           nextSignalTry.foreach(_.addInternalObserver(internalEventObserver, shouldCallMaybeWillStart = false))
         }
-      })
+      }
     }
   }
 
diff --git a/src/main/scala/com/raquo/airstream/flatten/SwitchSignalStream.scala b/src/main/scala/com/raquo/airstream/flatten/SwitchSignalStream.scala
index 5cb2f456..c6fb4e00 100644
--- a/src/main/scala/com/raquo/airstream/flatten/SwitchSignalStream.scala
+++ b/src/main/scala/com/raquo/airstream/flatten/SwitchSignalStream.scala
@@ -24,14 +24,14 @@ class SwitchSignalStream[A](
   private[this] val internalEventObserver: InternalObserver[A] = InternalObserver.fromTry[A](
     onTry = (nextTry, _) => {
       //println(s"> init trx from SwitchSignalStream.onValue($nextTry)")
-      new Transaction(trx => {
+      Transaction { trx =>
         if (isStarted) {
           fireTry(nextTry, trx)
           maybeCurrentSignalTry.foreach { _.foreach { currentSignal =>
             lastSeenSignalUpdateId = Protected.lastUpdateId(currentSignal)
           }}
         }
-      })
+      }
     }
   )
 
@@ -70,7 +70,7 @@ class SwitchSignalStream[A](
       lastSeenSignalUpdateId = -1
 
       //println(s"> init trx from SwitchSignalStream.onTry (new signal)")
-      new Transaction(trx => {
+      Transaction { trx =>
         if (isStarted) {
           // #Note: Timing is important here.
           // 1. Create the `trx` transaction, since we need that boundary when flattening
@@ -92,7 +92,7 @@ class SwitchSignalStream[A](
             nextSignal.addInternalObserver(internalEventObserver, shouldCallMaybeWillStart = false)
           }
         }
-      })
+      }
     }
   }
 
@@ -103,12 +103,12 @@ class SwitchSignalStream[A](
       val newSignalLastUpdateId = Protected.lastUpdateId(currentSignal)
       if (newSignalLastUpdateId != lastSeenSignalUpdateId) {
         //println(s"> init trx from SwitchSignalStream.onTry (same signal)")
-        new Transaction(trx => {
+        Transaction { trx =>
           if (isStarted) {
             fireTry(currentSignal.tryNow(), trx) // #Note[onStart,trx,loop]
             lastSeenSignalUpdateId = newSignalLastUpdateId
           }
-        })
+        }
       }
       currentSignal.addInternalObserver(internalEventObserver, shouldCallMaybeWillStart = false)
     })
diff --git a/src/main/scala/com/raquo/airstream/flatten/SwitchStream.scala b/src/main/scala/com/raquo/airstream/flatten/SwitchStream.scala
index 12bdeefc..64eb36d1 100644
--- a/src/main/scala/com/raquo/airstream/flatten/SwitchStream.scala
+++ b/src/main/scala/com/raquo/airstream/flatten/SwitchStream.scala
@@ -43,10 +43,10 @@ class SwitchStream[I, O](
   private[this] val internalEventObserver: InternalObserver[O] = InternalObserver[O](
     onNext = (nextEvent, _) => {
       //println(s"> init trx from SwitchEventStream.onValue(${nextEvent})")
-      new Transaction(fireValue(nextEvent, _))
+      Transaction(fireValue(nextEvent, _))
     },
     onError = (nextError, _) => {
-      new Transaction(fireError(nextError, _))
+      Transaction(fireError(nextError, _))
     }
   )
 
@@ -113,7 +113,7 @@ class SwitchStream[I, O](
   private def switchToNextError(nextError: Throwable, transaction: Option[Transaction]): Unit = {
     removeInternalObserverFromCurrentEventStream()
     maybeCurrentEventStreamTry = Failure(nextError)
-    transaction.fold[Unit](new Transaction(fireError(nextError, _)))(fireError(nextError, _)) // #Note[onStart,trx,loop]
+    transaction.fold[Unit](Transaction(fireError(nextError, _)))(fireError(nextError, _)) // #Note[onStart,trx,loop]
   }
 
   private def removeInternalObserverFromCurrentEventStream(): Unit = {
diff --git a/src/main/scala/com/raquo/airstream/state/Var.scala b/src/main/scala/com/raquo/airstream/state/Var.scala
index 3dfb3be6..dbb116d7 100644
--- a/src/main/scala/com/raquo/airstream/state/Var.scala
+++ b/src/main/scala/com/raquo/airstream/state/Var.scala
@@ -28,7 +28,7 @@ trait Var[A] extends SignalSource[A] with Sink[A] with Named {
 
   val writer: Observer[A] = Observer.fromTry { case nextTry => // Note: `case` syntax needed for Scala 2.12
     //println(s"> init trx from Var.writer(${nextTry})")
-    new Transaction(setCurrentValue(nextTry, _))
+    Transaction(setCurrentValue(nextTry, _))
   }
 
   /** Write values into a Var of Option[V] without manually wrapping in Some() */
@@ -47,21 +47,23 @@ trait Var[A] extends SignalSource[A] with Sink[A] with Named {
     * @param mod (currValue, nextInput) => nextValue
     */
   def updater[B](mod: (A, B) => A): Observer[B] = Observer.fromTry { case nextInputTry =>
-    new Transaction(trx => nextInputTry match {
-      case Success(nextInput) =>
-        tryNow() match {
-          case Success(currentValue) =>
-            val nextValue = Try(mod(currentValue, nextInput)) // this does catch exceptions in mod
-            setCurrentValue(nextValue, trx)
-          case Failure(err) =>
-            AirstreamError.sendUnhandledError(
-              VarError("Unable to update a failed Var. Consider Var#tryUpdater instead.", cause = Some(err))
-            )
-        }
-
-      case Failure(err) =>
-        setCurrentValue(Failure[A](err), trx)
-    })
+    Transaction { trx =>
+      nextInputTry match {
+        case Success(nextInput) =>
+          tryNow() match {
+            case Success(currentValue) =>
+              val nextValue = Try(mod(currentValue, nextInput)) // this does catch exceptions in mod
+              setCurrentValue(nextValue, trx)
+            case Failure(err) =>
+              AirstreamError.sendUnhandledError(
+                VarError("Unable to update a failed Var. Consider Var#tryUpdater instead.", cause = Some(err))
+              )
+          }
+
+        case Failure(err) =>
+          setCurrentValue(Failure[A](err), trx)
+      }
+    }
   }
 
   // @TODO[Scala3] When we don't need 2.12, remove 'case' from all PartialFunction instances that don't need it (e.g. Observer.fromTry)
@@ -70,13 +72,15 @@ trait Var[A] extends SignalSource[A] with Sink[A] with Named {
     *            Note: Must not throw!
     */
   def tryUpdater[B](mod: (Try[A], B) => Try[A]): Observer[B] = Observer.fromTry { case nextInputTry =>
-    new Transaction(trx => nextInputTry match {
-      case Success(nextInput) =>
-        val nextValue = mod(getCurrentValue, nextInput)
-        setCurrentValue(nextValue, trx)
-      case Failure(err) =>
-        setCurrentValue(Failure[A](err), trx)
-    })
+    Transaction { trx =>
+      nextInputTry match {
+        case Success(nextInput) =>
+          val nextValue = mod(getCurrentValue, nextInput)
+          setCurrentValue(nextValue, trx)
+        case Failure(err) =>
+          setCurrentValue(Failure[A](err), trx)
+      }
+    }
   }
 
   def zoom[B](in: A => B)(out: (A, B) => A)(implicit owner: Owner): Var[B] = {
@@ -94,7 +98,7 @@ trait Var[A] extends SignalSource[A] with Sink[A] with Named {
     * @param mod Note: guarded against exceptions
     */
   def update(mod: A => A): Unit = {
-    new Transaction(trx => {
+    Transaction { trx =>
       tryNow() match {
         case Success(currentValue) =>
           val nextValue = Try(mod(currentValue)) // this does catch exceptions in mod(currentValue)
@@ -104,17 +108,16 @@ trait Var[A] extends SignalSource[A] with Sink[A] with Named {
             VarError("Unable to update a failed Var. Consider Var#tryUpdate instead.", cause = Some(err))
           )
       }
-
-    })
+    }
   }
 
   /** @param mod Note: must not throw */
   def tryUpdate(mod: Try[A] => Try[A]): Unit = {
     //println(s"> init trx from Var.tryUpdate")
-    new Transaction(trx => {
+    Transaction { trx =>
       val nextValue = mod(getCurrentValue)
       setCurrentValue(nextValue, trx)
-    })
+    }
   }
 
   @inline def tryNow(): Try[A] = signal.tryNow()
@@ -162,12 +165,12 @@ object Var {
     */
   def setTry(values: VarTryTuple[_]*): Unit = {
     //println(s"> init trx from Var.set/setTry")
-    new Transaction(trx => {
+    Transaction { trx =>
       if (hasDuplicateVars(values.map(_.tuple))) {
         throw VarError("Unable to Var.{set,setTry}: the provided list of vars has duplicates. You can't make an observable emit more than one event per transaction.", cause = None)
       }
       values.foreach(setTryValue(_, trx))
-    })
+    }
   }
 
   /** Modify multiple Vars in the same Transaction
@@ -176,18 +179,18 @@ object Var {
     * Mod functions should be PURE.
     * - If a mod throws, the var will be set to a failed state.
     * - If you try to update a failed Var, `Var.update` will post an error to unhandled errors,
-    *   and none of the Vars will update.
+    * and none of the Vars will update.
     *
     * Reports an Airstream unhandled error:
-    *  1) if currentValue of any of the vars is a Failure.
-    *     This is atomic: an exception in any of the vars will prevent any of
-    *     the batched updates in this call from going through.
-    *  2) if input contains duplicate vars.
-    *     Airstream allows a maximum of one event per observable per transaction.
+    * 1) if currentValue of any of the vars is a Failure.
+    * This is atomic: an exception in any of the vars will prevent any of
+    * the batched updates in this call from going through.
+    * 2) if input contains duplicate vars.
+    * Airstream allows a maximum of one event per observable per transaction.
     */
   def update(mods: VarModTuple[_]*): Unit = {
     //println(s"> init trx from Var.update")
-    new Transaction(trx => {
+    Transaction { trx =>
       if (hasDuplicateVars(mods.map(_.tuple))) {
         throw VarError("Unable to Var.update: the provided list of vars has duplicates. You can't make an observable emit more than one event per transaction.", cause = None)
       }
@@ -195,12 +198,13 @@ object Var {
       val vars = mods.map(_.tuple._1)
       try {
         vars.foreach(_.now())
-      } catch { case err: Throwable =>
-        throw VarError("Unable to Var.update a failed Var. Consider Var.tryUpdate instead.", cause = Some(err))
+      } catch {
+        case err: Throwable =>
+          throw VarError("Unable to Var.update a failed Var. Consider Var.tryUpdate instead.", cause = Some(err))
       }
       val tryValues: Seq[VarTryTuple[_]] = tryMods.map(t => tryModToTryTuple(t))
       tryValues.foreach(setTryValue(_, trx))
-    })
+    }
   }
 
   /** Modify multiple Vars in the same Transaction
@@ -213,13 +217,13 @@ object Var {
     */
   def tryUpdate(mods: VarTryModTuple[_]*): Unit = {
     //println(s"> init trx from Var.tryUpdate")
-    new Transaction(trx => {
+    Transaction { trx =>
       if (hasDuplicateVars(mods.map(_.tuple))) {
         throw VarError("Unable to Var.tryUpdate: the provided list of vars has duplicates. You can't make an observable emit more than one event per transaction.", cause = None)
       }
       val tryValues: Seq[VarTryTuple[_]] = mods.map(t => tryModToTryTuple(t))
       tryValues.foreach(setTryValue(_, trx))
-    })
+    }
   }
 
   @inline private def toTryTuple[A](varTuple: VarTuple[A]): VarTryTuple[A] = {
diff --git a/src/main/scala/com/raquo/airstream/timing/DebounceStream.scala b/src/main/scala/com/raquo/airstream/timing/DebounceStream.scala
index e333542d..399d2d3d 100644
--- a/src/main/scala/com/raquo/airstream/timing/DebounceStream.scala
+++ b/src/main/scala/com/raquo/airstream/timing/DebounceStream.scala
@@ -35,7 +35,7 @@ class DebounceStream[A](
     maybeLastTimeoutHandle.foreach(js.timers.clearTimeout)
     maybeLastTimeoutHandle = js.timers.setTimeout(intervalMs.toDouble) {
       //println(s"> init trx from DebounceEventStream.onTry($nextValue)")
-      new Transaction(fireTry(nextValue, _))
+      Transaction(fireTry(nextValue, _))
     }
   }
 
diff --git a/src/main/scala/com/raquo/airstream/timing/DelayStream.scala b/src/main/scala/com/raquo/airstream/timing/DelayStream.scala
index 67dbe121..be0605e8 100644
--- a/src/main/scala/com/raquo/airstream/timing/DelayStream.scala
+++ b/src/main/scala/com/raquo/airstream/timing/DelayStream.scala
@@ -22,7 +22,7 @@ class DelayStream[A](
     timerHandle = js.timers.setTimeout(delayMs.toDouble) {
       //println(s"> init trx from DelayEventStream.onNext($nextValue)")
       timerHandles.splice(timerHandles.indexOf(timerHandle), deleteCount = 1) // Remove handle
-      new Transaction(fireValue(nextValue, _))
+      Transaction(fireValue(nextValue, _))
       ()
     }
     timerHandles.push(timerHandle)
@@ -32,7 +32,7 @@ class DelayStream[A](
     var timerHandle: SetTimeoutHandle = null
     timerHandle = js.timers.setTimeout(delayMs.toDouble) {
       timerHandles.splice(timerHandles.indexOf(timerHandle), deleteCount = 1) // Remove handle
-      new Transaction(fireError(nextError, _))
+      Transaction(fireError(nextError, _))
       ()
     }
     timerHandles.push(timerHandle)
diff --git a/src/main/scala/com/raquo/airstream/timing/JsPromiseSignal.scala b/src/main/scala/com/raquo/airstream/timing/JsPromiseSignal.scala
index f1d0f82c..10b00046 100644
--- a/src/main/scala/com/raquo/airstream/timing/JsPromiseSignal.scala
+++ b/src/main/scala/com/raquo/airstream/timing/JsPromiseSignal.scala
@@ -45,6 +45,6 @@ class JsPromiseSignal[A](promise: js.Promise[A]) extends WritableSignal[Option[A
     // #Note fireTry sets current value even if the signal has no observers
     val nextValue = nextPromiseValue.map(Some(_))
     //println(s"> init trx from FutureSignal($value)")
-    new Transaction(fireTry(nextValue, _)) // #Note[onStart,trx,async]
+    Transaction(fireTry(nextValue, _)) // #Note[onStart,trx,async]
   }
 }
diff --git a/src/main/scala/com/raquo/airstream/timing/JsPromiseStream.scala b/src/main/scala/com/raquo/airstream/timing/JsPromiseStream.scala
index 4c6f2f43..1ee6e5b0 100644
--- a/src/main/scala/com/raquo/airstream/timing/JsPromiseStream.scala
+++ b/src/main/scala/com/raquo/airstream/timing/JsPromiseStream.scala
@@ -33,7 +33,7 @@ class JsPromiseStream[A](promise: js.Promise[A], emitOnce: Boolean) extends Writ
         (nextValue: A) => {
           isPending = false
           //println(s"> init trx from FutureEventStream.init($nextValue)")
-          new Transaction(fireValue(nextValue, _))
+          Transaction(fireValue(nextValue, _))
           (): Unit | js.Thenable[Unit]
         },
         js.defined { (rawException: Any) => {
@@ -43,7 +43,7 @@ class JsPromiseStream[A](promise: js.Promise[A], emitOnce: Boolean) extends Writ
             case _ => js.JavaScriptException(rawException)
           }
           //println(s"> init trx from JsPromiseEventStream.init($nextError)")
-          new Transaction(fireError(nextError, _))
+          Transaction(fireError(nextError, _))
           (): Unit | js.Thenable[Unit]
         }}
       )
diff --git a/src/main/scala/com/raquo/airstream/timing/PeriodicStream.scala b/src/main/scala/com/raquo/airstream/timing/PeriodicStream.scala
index f0aef351..5f2bf33c 100644
--- a/src/main/scala/com/raquo/airstream/timing/PeriodicStream.scala
+++ b/src/main/scala/com/raquo/airstream/timing/PeriodicStream.scala
@@ -43,14 +43,14 @@ class PeriodicStream[A](
   }
 
   private def tick(): Unit = {
-    new Transaction(trx => { // #Note[onStart,trx,async]
+    Transaction { trx => // #Note[onStart,trx,async]
       if (isStarted) {
         // This cycle should also be broken by clearTimeout() in onStop,
         // but just in case of some weird timing I put isStarted check here.
         fireValue(currentValue, trx)
         setNext()
       }
-    })
+    }
   }
 
   private def setNext(): Unit = {
@@ -63,7 +63,7 @@ class PeriodicStream[A](
       case Success(None) =>
         resetTo(initial, tickNext = false)
       case Failure(err) =>
-        new Transaction(fireError(err, _)) // #Note[onStart,trx,async]
+        Transaction(fireError(err, _)) // #Note[onStart,trx,async]
     }
   }
 
diff --git a/src/main/scala/com/raquo/airstream/timing/ThrottleStream.scala b/src/main/scala/com/raquo/airstream/timing/ThrottleStream.scala
index 33fb2521..d6a476c3 100644
--- a/src/main/scala/com/raquo/airstream/timing/ThrottleStream.scala
+++ b/src/main/scala/com/raquo/airstream/timing/ThrottleStream.scala
@@ -53,7 +53,7 @@ class ThrottleStream[A](
       maybeFirstTimeoutHandle = js.timers.setTimeout(0) {
         maybeFirstTimeoutHandle = js.undefined
         //println(s"> init trx from leading ThrottleEventStream.onTry($nextValue)")
-        new Transaction(fireTry(nextValue, _))
+        Transaction(fireTry(nextValue, _))
       }
 
     } else {
@@ -62,7 +62,7 @@ class ThrottleStream[A](
       maybeLastTimeoutHandle = js.timers.setTimeout(remainingMs.toDouble) {
         lastEmittedEventMs = js.Date.now() // @TODO Should this fire now, or inside the transaction below?
         //println(s"> init trx from ThrottleEventStream.onTry($nextValue)")
-        new Transaction(fireTry(nextValue, _))
+        Transaction(fireTry(nextValue, _))
       }
     }
   }
diff --git a/src/main/scala/com/raquo/airstream/web/AjaxStream.scala b/src/main/scala/com/raquo/airstream/web/AjaxStream.scala
index 06c0965c..a8e19ff9 100644
--- a/src/main/scala/com/raquo/airstream/web/AjaxStream.scala
+++ b/src/main/scala/com/raquo/airstream/web/AjaxStream.scala
@@ -80,9 +80,9 @@ class AjaxStream(
         maybePendingRequest = js.undefined
         val status = request.status
         if (isStatusCodeSuccess(status))
-          new Transaction(fireValue(request, _))
+          Transaction(fireValue(request, _))
         else
-          new Transaction(fireError(AjaxStatusError(request, status, s"Ajax request failed: $status ${request.statusText}"), _))
+          Transaction(fireError(AjaxStatusError(request, status, s"Ajax request failed: $status ${request.statusText}"), _))
       }
     }
 
@@ -94,21 +94,21 @@ class AjaxStream(
         //  - `ev` is not actually a dom.ErrorEvent, but a useless dom.ProgressEvent
         //  - Reasons could be network, DNS, CORS, etc.
 
-        new Transaction(fireError(AjaxNetworkError(request, s"Ajax request failed: unknown network reason."), _))
+        Transaction(fireError(AjaxNetworkError(request, s"Ajax request failed: unknown network reason."), _))
       }
     }
 
     request.onabort = (_: js.Any) => {
       if (maybePendingRequest.contains(request)) {
         maybePendingRequest = js.undefined
-        new Transaction(fireError(AjaxAbort(request), _))
+        Transaction(fireError(AjaxAbort(request), _))
       }
     }
 
     request.ontimeout = (_: dom.Event) => {
       if (maybePendingRequest.contains(request)) {
         maybePendingRequest = js.undefined
-        new Transaction(fireError(AjaxTimeout(request), _))
+        Transaction(fireError(AjaxTimeout(request), _))
       }
     }
 
diff --git a/src/main/scala/com/raquo/airstream/web/FetchStream.scala b/src/main/scala/com/raquo/airstream/web/FetchStream.scala
index 1bfc67ca..3995136c 100644
--- a/src/main/scala/com/raquo/airstream/web/FetchStream.scala
+++ b/src/main/scala/com/raquo/airstream/web/FetchStream.scala
@@ -143,7 +143,7 @@ class FetchStream private[web] (
     maybeAbortStream.map { _ =>
       InternalObserver[Any](
         onNext = (_, _) => maybeAbortController.get.abort(),
-        onError = (err, _) => new Transaction(fireError(err, _))
+        onError = (err, _) => Transaction(fireError(err, _))
       )
     }
   }
@@ -156,7 +156,7 @@ class FetchStream private[web] (
       val responsePromise = dom.Fetch.fetch(url, requestInit)
       // #TODO[Integrity] Is it ok to emit asynchronously here? Maybe we should save `responsePromise` and emit it `onStart`?
       js.timers.setTimeout(0) {
-        new Transaction(fireValue(responsePromise, _))
+        Transaction(fireValue(responsePromise, _))
       }
       hasEmittedEvents = true
     }
diff --git a/src/test/scala/com/raquo/airstream/core/PullResetSignalSpec.scala b/src/test/scala/com/raquo/airstream/core/PullResetSignalSpec.scala
index 5ad56f06..f72d9165 100644
--- a/src/test/scala/com/raquo/airstream/core/PullResetSignalSpec.scala
+++ b/src/test/scala/com/raquo/airstream/core/PullResetSignalSpec.scala
@@ -416,15 +416,15 @@ class PullResetSignalSpec extends UnitSpec {
 
     v.set(11)
 
-    // With `new Transaction`, these could be delayed if we're already
+    // With `Transaction { ... }`, these could be delayed if we're already
     // inside a transaction (in the test, we aren't), and also we can't
     // return the value from inside the transaction (due to the potential
     // delay)
-    new Transaction(_ => {
+    Transaction { _ =>
       isPositive.addObserver(Observer.empty)(owner)
       isEven.addObserver(Observer.empty)(owner)
       combined.addObserver(Observer.empty)(owner)
-    })
+    }
 
     log.toList shouldBe List(
       "11 isPositive = true",
@@ -633,12 +633,12 @@ class PullResetSignalSpec extends UnitSpec {
     AirstreamError.unregisterUnhandledErrorCallback(AirstreamError.consoleErrorCallback)
 
     try {
-      new Transaction(_ => {
+      Transaction { _ =>
         isPositive.addObserver(Observer.empty)(owner)
         isEven.addObserver(Observer.empty)(owner)
         throw new Exception(sharedBlockErrorMsg)
         // combined.addObserver(Observer.empty)(owner)
-      })
+      }
 
       log.toList shouldBe List(
         "11 isPositive = true",
@@ -653,9 +653,9 @@ class PullResetSignalSpec extends UnitSpec {
 
       // --
 
-      new Transaction(_ => {
+      Transaction { _ =>
         combined.addObserver(Observer.empty)(owner)
-      })
+      }
 
       v.set(-12)
 
diff --git a/src/test/scala/com/raquo/airstream/core/TransactionSpec.scala b/src/test/scala/com/raquo/airstream/core/TransactionSpec.scala
index fbf5f1ac..14320b5b 100644
--- a/src/test/scala/com/raquo/airstream/core/TransactionSpec.scala
+++ b/src/test/scala/com/raquo/airstream/core/TransactionSpec.scala
@@ -77,9 +77,9 @@ class TransactionSpec extends UnitSpec {
 
       bus.events.foreach { num =>
         if (num % 2 == 0) {
-          new Transaction(_ => {
+          Transaction { _ =>
             throw new Exception("Random error in transaction")
-          })
+          }
         } else {
           log.update(_ :+ num)
         }
diff --git a/src/test/scala/com/raquo/airstream/misc/SplitSignalSpec.scala b/src/test/scala/com/raquo/airstream/misc/SplitSignalSpec.scala
index c56e2cd5..6f1c3af4 100644
--- a/src/test/scala/com/raquo/airstream/misc/SplitSignalSpec.scala
+++ b/src/test/scala/com/raquo/airstream/misc/SplitSignalSpec.scala
@@ -685,7 +685,7 @@ class SplitSignalSpec extends UnitSpec with BeforeAndAfter {
           }(owner)
         )
         // #Note: Test that our dropping logic works does not break events scheduled after transaction boundary
-        new Transaction(_ => {
+        Transaction { _ =>
           DynamicSubscription.subscribeCallback(
             innerDynamicOwner,
             owner => fooSignal.foreach { foo =>
@@ -693,7 +693,7 @@ class SplitSignalSpec extends UnitSpec with BeforeAndAfter {
               effects += Effect(s"new-trx-update-child-$key", foo.id + "-" + foo.version.toString)
             }(owner)
           )
-        })
+        }
         Bar(key)
       })