diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c125e70
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.bsp
+.metals
+.vscode
+target/
\ No newline at end of file
diff --git a/.scalafmt.conf b/.scalafmt.conf
new file mode 100644
index 0000000..439185c
--- /dev/null
+++ b/.scalafmt.conf
@@ -0,0 +1,2 @@
+version = "3.6.1"
+runner.dialect = scala213
\ No newline at end of file
diff --git a/app/src/main/scala/App.scala b/app/src/main/scala/App.scala
new file mode 100644
index 0000000..e18fd41
--- /dev/null
+++ b/app/src/main/scala/App.scala
@@ -0,0 +1,8 @@
+import cats.syntax.all._
+import PersonSemigroup._
+
+object App {
+  def main(args: Array[String]): Unit = {
+    println(Person("foo", 2) |+| Person("bar", 3))
+  }
+}
diff --git a/build.sbt b/build.sbt
new file mode 100644
index 0000000..3e41463
--- /dev/null
+++ b/build.sbt
@@ -0,0 +1,21 @@
+ThisBuild / scalaVersion := "3.2.2"
+ThisBuild / crossScalaVersions := Seq("2.13.10", "3.2.2")
+
+lazy val personOld = project
+lazy val personNew = project.settings(
+  mimaPreviousClassfiles := Map(
+    projectID.value -> (personOld / Compile / classDirectory).value
+  ),
+  mimaReportBinaryIssues :=
+    mimaReportBinaryIssues
+      .dependsOn(personOld / Compile / compile)
+      .value
+)
+
+lazy val lib = project
+  .settings(
+    libraryDependencies += "org.typelevel" %% "kittens" % "3.0.0"
+  )
+  .dependsOn(personOld % Provided)
+
+val app = project.dependsOn(lib, personNew)
diff --git a/lib/src/main/scala/PersonSemigroup.scala b/lib/src/main/scala/PersonSemigroup.scala
new file mode 100644
index 0000000..a8e72b3
--- /dev/null
+++ b/lib/src/main/scala/PersonSemigroup.scala
@@ -0,0 +1,6 @@
+import cats._
+import cats.derived._
+
+object PersonSemigroup {
+  implicit def instance: Semigroup[Person] = semiauto.semigroup
+}
diff --git a/personNew/src/main/scala/Person.scala b/personNew/src/main/scala/Person.scala
new file mode 100644
index 0000000..646aced
--- /dev/null
+++ b/personNew/src/main/scala/Person.scala
@@ -0,0 +1,17 @@
+case class Person private (name: String, age: Int) {
+  def this(name: String) = this(name, -1)
+
+  def withName(name: String): Person = copy(name = name)
+  def withAge(age: Int): Person = copy(age = age)
+
+  private def copy(name: String = this.name, age: Int = this.age): Person =
+    new Person(name, age)
+}
+
+object Person {
+  def apply(name: String, age: Int): Person = new Person(name, age)
+
+  def apply(name: String): Person = new Person(name)
+
+  private def unapply(person: Person): Some[Person] = Some(person)
+}
diff --git a/personOld/src/main/scala/Person.scala b/personOld/src/main/scala/Person.scala
new file mode 100644
index 0000000..67d7541
--- /dev/null
+++ b/personOld/src/main/scala/Person.scala
@@ -0,0 +1,11 @@
+case class Person private (name: String) {
+  def withName(name: String): Person = copy(name = name)
+
+  private def copy(name: String = this.name): Person =
+    new Person(name)
+}
+
+object Person {
+  def apply(name: String): Person = new Person(name)
+  private def unapply(person: Person): Some[Person] = Some(person)
+}
diff --git a/project/build.properties b/project/build.properties
new file mode 100644
index 0000000..46e43a9
--- /dev/null
+++ b/project/build.properties
@@ -0,0 +1 @@
+sbt.version=1.8.2
diff --git a/project/plugins.sbt b/project/plugins.sbt
new file mode 100644
index 0000000..6984693
--- /dev/null
+++ b/project/plugins.sbt
@@ -0,0 +1 @@
+addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.2")