diff --git a/core-macros/src/main/scala/sbt/internal/util/appmacro/Instance.scala b/core-macros/src/main/scala/sbt/internal/util/appmacro/Instance.scala
index a2d41f3e4..5d4f53900 100644
--- a/core-macros/src/main/scala/sbt/internal/util/appmacro/Instance.scala
+++ b/core-macros/src/main/scala/sbt/internal/util/appmacro/Instance.scala
@@ -49,9 +49,7 @@ object Instance {
   trait Transform[C <: blackbox.Context with Singleton, N[_]] {
     def apply(in: C#Tree): C#Tree
   }
-  def idTransform[C <: blackbox.Context with Singleton]: Transform[C, Id] = new Transform[C, Id] {
-    def apply(in: C#Tree): C#Tree = in
-  }
+  def idTransform[C <: blackbox.Context with Singleton]: Transform[C, Id] = in => in
 
   /**
    * Implementation of a macro that provides a direct syntax for applicative functors and monads.
diff --git a/internal/util-collection/src/main/scala/sbt/util/Show.scala b/internal/util-collection/src/main/scala/sbt/util/Show.scala
index d910b5319..9c6ce80ab 100644
--- a/internal/util-collection/src/main/scala/sbt/util/Show.scala
+++ b/internal/util-collection/src/main/scala/sbt/util/Show.scala
@@ -11,9 +11,7 @@ trait Show[A] {
   def show(a: A): String
 }
 object Show {
-  def apply[A](f: A => String): Show[A] = new Show[A] { def show(a: A): String = f(a) }
+  def apply[A](f: A => String): Show[A] = a => f(a)
 
-  def fromToString[A]: Show[A] = new Show[A] {
-    def show(a: A): String = a.toString
-  }
+  def fromToString[A]: Show[A] = _.toString
 }
diff --git a/main-actions/src/main/scala/sbt/TestResultLogger.scala b/main-actions/src/main/scala/sbt/TestResultLogger.scala
index 5f196f2b5..19b56fafe 100644
--- a/main-actions/src/main/scala/sbt/TestResultLogger.scala
+++ b/main-actions/src/main/scala/sbt/TestResultLogger.scala
@@ -58,10 +58,7 @@ object TestResultLogger {
 
   /** Creates a `TestResultLogger` using a given function. */
   def apply(f: (Logger, Output, String) => Unit): TestResultLogger =
-    new TestResultLogger {
-      override def run(log: Logger, results: Output, taskName: String) =
-        f(log, results, taskName)
-    }
+    (log, results, taskName) => f(log, results, taskName)
 
   /** Creates a `TestResultLogger` that ignores its input and always performs the same logging. */
   def const(f: Logger => Unit) = apply((l, _, _) => f(l))
diff --git a/main-settings/src/main/scala/sbt/Reference.scala b/main-settings/src/main/scala/sbt/Reference.scala
index a605e16f5..76b963d85 100644
--- a/main-settings/src/main/scala/sbt/Reference.scala
+++ b/main-settings/src/main/scala/sbt/Reference.scala
@@ -58,24 +58,17 @@ object RootProject {
   def apply(base: File): RootProject = RootProject(IO toURI base)
 }
 object Reference {
-  implicit val resolvedReferenceOrdering: Ordering[ResolvedReference] =
-    new Ordering[ResolvedReference] {
-      def compare(a: ResolvedReference, b: ResolvedReference): Int = (a, b) match {
-        case (ba: BuildRef, bb: BuildRef)     => buildRefOrdering.compare(ba, bb)
-        case (pa: ProjectRef, pb: ProjectRef) => projectRefOrdering.compare(pa, pb)
-        case (_: BuildRef, _: ProjectRef)     => -1
-        case (_: ProjectRef, _: BuildRef)     => 1
-      }
-    }
-  implicit val buildRefOrdering: Ordering[BuildRef] = new Ordering[BuildRef] {
-    def compare(a: BuildRef, b: BuildRef): Int = a.build compareTo b.build
+  implicit val resolvedReferenceOrdering: Ordering[ResolvedReference] = {
+    case (ba: BuildRef, bb: BuildRef)     => buildRefOrdering.compare(ba, bb)
+    case (pa: ProjectRef, pb: ProjectRef) => projectRefOrdering.compare(pa, pb)
+    case (_: BuildRef, _: ProjectRef)     => -1
+    case (_: ProjectRef, _: BuildRef)     => 1
   }
+  implicit val buildRefOrdering: Ordering[BuildRef] = (a, b) => a.build compareTo b.build
 
-  implicit val projectRefOrdering: Ordering[ProjectRef] = new Ordering[ProjectRef] {
-    def compare(a: ProjectRef, b: ProjectRef): Int = {
-      val bc = a.build compareTo b.build
-      if (bc == 0) a.project compareTo b.project else bc
-    }
+  implicit val projectRefOrdering: Ordering[ProjectRef] = (a, b) => {
+    val bc = a.build compareTo b.build
+    if (bc == 0) a.project compareTo b.project else bc
   }
 
   def display(ref: Reference): String =
diff --git a/main-settings/src/main/scala/sbt/std/TaskMacro.scala b/main-settings/src/main/scala/sbt/std/TaskMacro.scala
index bf910a687..965a3f38f 100644
--- a/main-settings/src/main/scala/sbt/std/TaskMacro.scala
+++ b/main-settings/src/main/scala/sbt/std/TaskMacro.scala
@@ -418,9 +418,7 @@ object TaskMacro {
   private[this] def iInitializeMacro[M[_], T](c: blackbox.Context)(t: c.Expr[T])(
       f: c.Expr[T] => c.Expr[M[T]]
   )(implicit tt: c.WeakTypeTag[T], mt: c.WeakTypeTag[M[T]]): c.Expr[Initialize[M[T]]] = {
-    val inner: Transform[c.type, M] = new Transform[c.type, M] {
-      def apply(in: c.Tree): c.Tree = f(c.Expr[T](in)).tree
-    }
+    val inner: Transform[c.type, M] = (in: c.Tree) => f(c.Expr[T](in)).tree
     val cond = c.Expr[T](conditionInputTaskTree(c)(t.tree))
     Instance
       .contImpl[T, M](c, InitializeInstance, InputInitConvert, MixedBuilder, EmptyLinter)(
@@ -464,9 +462,7 @@ object TaskMacro {
   private[this] def iParserMacro[M[_], T](c: blackbox.Context)(t: c.Expr[T])(
       f: c.Expr[T] => c.Expr[M[T]]
   )(implicit tt: c.WeakTypeTag[T], mt: c.WeakTypeTag[M[T]]): c.Expr[State => Parser[M[T]]] = {
-    val inner: Transform[c.type, M] = new Transform[c.type, M] {
-      def apply(in: c.Tree): c.Tree = f(c.Expr[T](in)).tree
-    }
+    val inner: Transform[c.type, M] = (in: c.Tree) => f(c.Expr[T](in)).tree
     Instance.contImpl[T, M](c, ParserInstance, ParserConvert, MixedBuilder, LinterDSL.Empty)(
       Left(t),
       inner
diff --git a/main/src/main/scala/sbt/Main.scala b/main/src/main/scala/sbt/Main.scala
index 2bac36751..f700346ca 100644
--- a/main/src/main/scala/sbt/Main.scala
+++ b/main/src/main/scala/sbt/Main.scala
@@ -120,10 +120,8 @@ object StandardMain {
   import scalacache.caffeine._
   private[sbt] lazy val cache: Cache[Any] = CaffeineCache[Any]
 
-  private[sbt] val shutdownHook = new Thread(new Runnable {
-    def run(): Unit = {
-      exchange.shutdown
-    }
+  private[sbt] val shutdownHook = new Thread(() => {
+    exchange.shutdown
   })
 
   def runManaged(s: State): xsbti.MainResult = {
diff --git a/sbt/src/main/scala/AllSyntax.scala b/sbt/src/main/scala/AllSyntax.scala
index ccd5bff85..bb48c2c2c 100644
--- a/sbt/src/main/scala/AllSyntax.scala
+++ b/sbt/src/main/scala/AllSyntax.scala
@@ -10,10 +10,7 @@ package sbt
 // Todo share this this io.syntax
 private[sbt] trait IOSyntax0 extends IOSyntax1 {
   implicit def alternative[A, B](f: A => Option[B]): Alternative[A, B] =
-    new Alternative[A, B] {
-      def |(g: A => Option[B]) =
-        (a: A) => f(a) orElse g(a)
-    }
+    g => a => f(a) orElse g(a)
 }
 private[sbt] trait Alternative[A, B] {
   def |(g: A => Option[B]): A => Option[B]