diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c1d0e208..69f8abc1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -24,7 +24,7 @@ jobs:
       with:
         jvm: 8
     - name: Test
-      run: sbtn ++${{ matrix.SCALA_VERSION }} test
+      run: ./mill -i '__[${{ matrix.SCALA_VERSION }}].test'
 
   bin-compat:
     runs-on: ubuntu-latest
@@ -37,8 +37,8 @@ jobs:
     - uses: coursier/setup-action@v1.3
       with:
         jvm: 8
-    - name: Test
-      run: sbtn +mimaReportBinaryIssues
+    - name: Check
+      run: ./mill -i __.mimaReportBinaryIssues
 
   format:
     runs-on: ubuntu-latest
@@ -72,7 +72,7 @@ jobs:
     - name: Wrap GPG binary
       run: .github/scripts/wrap-gpg.sh
     - name: Release
-      run: sbtn ci-release
+      run: ./mill -i publishSonatype __.publishArtifacts
       env:
         PGP_PASSPHRASE: ${{ secrets.PUBLISH_SECRET_KEY_PASSWORD }}
         PGP_SECRET: ${{ secrets.PUBLISH_SECRET_KEY }}
diff --git a/.gitignore b/.gitignore
index 7d18b4f3..5641b795 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-target/
+out/
 .bsp/
 .idea
 .idea_modules
@@ -7,4 +7,3 @@ target/
 .bloop/
 .metals/
 .vscode/
-project/metals.sbt
diff --git a/.mill-version b/.mill-version
new file mode 100644
index 00000000..2427081a
--- /dev/null
+++ b/.mill-version
@@ -0,0 +1 @@
+0.11.7-109-59a5cb
\ No newline at end of file
diff --git a/build.sbt b/build.sbt
deleted file mode 100644
index 7ff0789b..00000000
--- a/build.sbt
+++ /dev/null
@@ -1,134 +0,0 @@
-import sbtcrossproject.crossProject
-
-import Settings._
-
-inThisBuild(List(
-  organization := "com.github.alexarchambault",
-  homepage     := Some(url("https://github.com/alexarchambault/case-app")),
-  licenses     := Seq("Apache 2.0" -> url("http://opensource.org/licenses/Apache-2.0")),
-  developers := List(
-    Developer(
-      "alexarchambault",
-      "Alexandre Archambault",
-      "",
-      url("https://github.com/alexarchambault")
-    )
-  )
-))
-
-lazy val annotations = crossProject(JSPlatform, JVMPlatform, NativePlatform)
-  .nativeConfigure(_.disablePlugins(MimaPlugin))
-  .jvmSettings(Mima.settings)
-  .jsSettings(Mima.settings)
-  .settings(
-    shared,
-    caseAppPrefix
-  )
-
-lazy val annotationsJVM    = annotations.jvm
-lazy val annotationsJS     = annotations.js
-lazy val annotationsNative = annotations.native
-
-lazy val util = crossProject(JSPlatform, JVMPlatform, NativePlatform)
-  .nativeConfigure(_.disablePlugins(MimaPlugin))
-  .jvmSettings(Mima.settings)
-  .jsSettings(Mima.settings)
-  .settings(
-    shared,
-    caseAppPrefix,
-    libraryDependencies ++= {
-      val sv = scalaVersion.value
-      if (sv.startsWith("2."))
-        Seq(
-          Deps.shapeless.value,
-          Deps.scalaCompiler.value % "provided",
-          Deps.scalaReflect.value  % "provided"
-        )
-      else
-        Nil
-    }
-  )
-
-lazy val utilJVM    = util.jvm
-lazy val utilJS     = util.js
-lazy val utilNative = util.native
-
-lazy val cats = crossProject(JSPlatform, JVMPlatform)
-  .dependsOn(core)
-  .jvmSettings(Mima.settings)
-  .jsSettings(Mima.settings)
-  .settings(
-    shared,
-    name := "case-app-cats",
-    libraryDependencies ++= Seq(
-      Deps.catsEffect3.value
-    ),
-    libraryDependencies += Deps.utest.value % Test,
-    testFrameworks += new TestFramework("utest.runner.Framework")
-  )
-
-lazy val catsJVM = cats.jvm
-lazy val catsJS  = cats.js
-
-lazy val cats2 = crossProject(JSPlatform, JVMPlatform)
-  .dependsOn(core)
-  .jvmSettings(Mima.settings)
-  .jsSettings(Mima.settings)
-  .settings(
-    shared,
-    name              := "case-app-cats-effect-2",
-    Compile / sources := (catsJVM / Compile / sources).value,
-    libraryDependencies ++= Seq(
-      Deps.catsEffect2.value
-    ),
-    libraryDependencies += Deps.utest.value % Test,
-    testFrameworks += new TestFramework("utest.runner.Framework")
-  )
-
-lazy val cats2JVM = cats2.jvm
-lazy val cats2JS  = cats2.js
-
-lazy val core = crossProject(JSPlatform, JVMPlatform, NativePlatform)
-  .nativeConfigure(_.disablePlugins(MimaPlugin))
-  .dependsOn(annotations, util)
-  .jvmSettings(Mima.settings)
-  .jsSettings(Mima.settings)
-  .settings(
-    shared,
-    name := "case-app",
-    libraryDependencies ++= {
-      val sv = scalaVersion.value
-      val maybeDataClass =
-        if (sv.startsWith("2.")) Seq(Deps.dataClass % Provided)
-        else Nil
-      Seq(Deps.sourcecode.value) ++ maybeDataClass
-    }
-  )
-
-lazy val coreJVM    = core.jvm
-lazy val coreJS     = core.js
-lazy val coreNative = core.native
-
-lazy val tests = crossProject(JSPlatform, JVMPlatform, NativePlatform)
-  .disablePlugins(MimaPlugin)
-  .dependsOn(core)
-  .settings(
-    shared,
-    caseAppPrefix,
-    publish / skip := true,
-    libraryDependencies ++= Seq(
-      Deps.pprint.value % Test,
-      Deps.utest.value  % Test
-    ),
-    testFrameworks += new TestFramework("utest.runner.Framework")
-  )
-
-lazy val testsJVM    = tests.jvm
-lazy val testsJS     = tests.js
-lazy val testsNative = tests.native
-
-disablePlugins(MimaPlugin)
-publish / skip     := true
-crossScalaVersions := Nil
-
-Global / onChangedBuildSource := ReloadOnSourceChanges
diff --git a/build.sc b/build.sc
new file mode 100644
index 00000000..4100b877
--- /dev/null
+++ b/build.sc
@@ -0,0 +1,427 @@
+import $ivy.`com.github.lolgab::mill-mima::0.0.23`
+
+import com.github.lolgab.mill.mima.Mima
+import mill._
+import mill.scalajslib._
+import mill.scalalib._
+import mill.scalanativelib._
+
+import scala.concurrent.duration.DurationInt
+
+object Versions {
+  def scala212 = "2.12.19"
+  def scala213 = "2.13.14"
+  def scala3   = "3.3.3"
+  def scala    = Seq(scala212, scala213, scala3)
+
+  def scalaJs     = "1.16.0"
+  def scalaNative = "0.5.2"
+}
+
+object Deps {
+  def catsEffect                = ivy"org.typelevel::cats-effect::3.5.4"
+  def catsEffect2               = ivy"org.typelevel::cats-effect::2.5.5"
+  def dataClass                 = ivy"io.github.alexarchambault::data-class:0.2.6"
+  def macroParadise             = ivy"org.scalamacros:::paradise:2.1.1"
+  def pprint                    = ivy"com.lihaoyi::pprint::0.9.0"
+  def scalaCompiler(sv: String) = ivy"org.scala-lang:scala-compiler:$sv"
+  def scalaReflect(sv: String)  = ivy"org.scala-lang:scala-reflect:$sv"
+  def shapeless                 = ivy"com.chuusai::shapeless::2.3.12"
+  def sourcecode                = ivy"com.lihaoyi::sourcecode::0.4.2"
+  def utest                     = ivy"com.lihaoyi::utest::0.8.3"
+}
+
+object annotations extends Module {
+  object jvm    extends Cross[AnnotationsJvm](Versions.scala)
+  object js     extends Cross[AnnotationsJs](Versions.scala)
+  object native extends Cross[AnnotationsNative](Versions.scala)
+
+  trait AnnotationsJvm    extends Annotations with MimaChecks
+  trait AnnotationsJs     extends Annotations with CaseAppScalaJsModule with MimaChecks
+  trait AnnotationsNative extends Annotations with CaseAppScalaNativeModule
+
+  trait Annotations extends CrossSbtModule with CrossSources with CaseAppPublishModule {
+    def artifactName = "case-app-annotations"
+  }
+}
+
+object util extends Module {
+  object jvm    extends Cross[UtilJvm](Versions.scala)
+  object js     extends Cross[UtilJs](Versions.scala)
+  object native extends Cross[UtilNative](Versions.scala)
+
+  trait UtilJvm    extends Util with MimaChecks
+  trait UtilJs     extends Util with CaseAppScalaJsModule with MimaChecks
+  trait UtilNative extends Util with CaseAppScalaNativeModule
+
+  trait Util extends CrossSbtModule with CrossSources with CaseAppPublishModule {
+    def artifactName = "case-app-util"
+    def ivyDeps = T {
+      if (scalaVersion().startsWith("2."))
+        Agg(Deps.shapeless)
+      else
+        Agg()
+    }
+    def compileIvyDeps = T {
+      if (scalaVersion().startsWith("2."))
+        Agg(
+          Deps.scalaCompiler(scalaVersion()),
+          Deps.scalaReflect(scalaVersion())
+        )
+      else
+        Agg()
+    }
+  }
+}
+
+object core extends Module {
+  object jvm    extends Cross[CoreJvm](Versions.scala)
+  object js     extends Cross[CoreJs](Versions.scala)
+  object native extends Cross[CoreNative](Versions.scala)
+
+  trait CoreJvm extends Core with MimaChecks {
+    def moduleDeps = Seq(
+      annotations.jvm(),
+      util.jvm()
+    )
+
+    object test extends Tests with TestCrossSources {
+      def ivyDeps       = Agg(Deps.utest)
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+  trait CoreJs extends Core with CaseAppScalaJsModule with MimaChecks {
+    def moduleDeps = Seq(
+      annotations.js(),
+      util.js()
+    )
+
+    object test extends SbtModuleTests with ScalaJSTests with TestCrossSources {
+      def ivyDeps       = Agg(Deps.utest)
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+  trait CoreNative extends Core with CaseAppScalaNativeModule {
+    def moduleDeps = Seq(
+      annotations.native(),
+      util.native()
+    )
+
+    object test extends SbtModuleTests with ScalaNativeTests with TestCrossSources {
+      def ivyDeps       = Agg(Deps.utest)
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+
+  trait Core extends CrossSbtModule with CrossSources with CaseAppPublishModule {
+    def artifactName = "case-app"
+    def ivyDeps = T {
+      val maybeDataClass =
+        if (scalaVersion().startsWith("2.")) Agg(Deps.dataClass)
+        else Agg.empty
+      Agg(Deps.sourcecode) ++ maybeDataClass
+    }
+    def scalacOptions = T {
+      val maybeMacroAnn =
+        if (scalaVersion().startsWith("2.13."))
+          Seq("-Ymacro-annotations")
+        else
+          Nil
+      super.scalacOptions() ++ maybeMacroAnn
+    }
+    def scalacPluginIvyDeps = T {
+      if (scalaVersion().startsWith("2.12."))
+        Agg(Deps.macroParadise)
+      else
+        Agg.empty
+    }
+  }
+}
+
+object cats extends Module {
+  object jvm extends Cross[CatsJvm](Versions.scala)
+  object js  extends Cross[CatsJs](Versions.scala)
+
+  trait CatsJvm extends Cats with MimaChecks {
+    def moduleDeps = Seq(core.jvm())
+
+    object test extends Tests with TestCrossSources {
+      def ivyDeps       = Agg(Deps.utest)
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+  trait CatsJs extends Cats with CaseAppScalaJsModule with MimaChecks {
+    def moduleDeps = Seq(core.js())
+
+    object test extends SbtModuleTests with ScalaJSTests with TestCrossSources {
+      def ivyDeps       = Agg(Deps.utest)
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+
+  trait Cats extends CrossSbtModule with CrossSources with CaseAppPublishModule {
+    def artifactName = "case-app-cats"
+    def ivyDeps      = Agg(Deps.catsEffect)
+  }
+}
+
+object cats2 extends Module {
+  object jvm extends Cross[Cats2Jvm](Versions.scala)
+  object js  extends Cross[Cats2Js](Versions.scala)
+
+  trait Cats2Jvm extends Cats2 with MimaChecks {
+    def moduleDeps = Seq(core.jvm())
+    def sources    = cats.jvm().sources()
+
+    object test extends Tests with TestCrossSources {
+      def ivyDeps       = Agg(Deps.utest)
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+  trait Cats2Js extends Cats2 with CaseAppScalaJsModule with MimaChecks {
+    def moduleDeps = Seq(core.js())
+    def sources    = cats.js().sources()
+
+    object test extends SbtModuleTests with ScalaJSTests with TestCrossSources {
+      def ivyDeps       = Agg(Deps.utest)
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+
+  trait Cats2 extends CrossSbtModule with CrossSources with CaseAppPublishModule {
+    def artifactName = "case-app-cats-effect-2"
+    def ivyDeps      = Agg(Deps.catsEffect2)
+  }
+}
+
+object tests extends Module {
+  object jvm    extends Cross[TestsJvm](Versions.scala)
+  object js     extends Cross[TestsJs](Versions.scala)
+  object native extends Cross[TestsNative](Versions.scala)
+
+  trait TestsJvm extends Tests0 {
+    def moduleDeps = Seq(core.jvm())
+
+    object test extends Tests with TestCrossSources {
+      def ivyDeps = Agg(
+        Deps.pprint,
+        Deps.utest
+      )
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+  trait TestsJs extends Tests0 with CaseAppScalaJsModule {
+    def moduleDeps = Seq(core.js())
+
+    object test extends SbtModuleTests with ScalaJSTests with TestCrossSources {
+      def ivyDeps = Agg(
+        Deps.pprint,
+        Deps.utest
+      )
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+  trait TestsNative extends Tests0 with CaseAppScalaNativeModule {
+    def moduleDeps = Seq(core.native())
+
+    object test extends SbtModuleTests with ScalaNativeTests with TestCrossSources {
+      def ivyDeps = Agg(
+        Deps.pprint,
+        Deps.utest
+      )
+      def testFramework = "utest.runner.Framework"
+    }
+  }
+
+  trait Tests0 extends CrossSbtModule with CrossSources {
+    def ivyDeps = T {
+      val maybeDataClass =
+        if (scalaVersion().startsWith("2.")) Agg(Deps.dataClass)
+        else Agg.empty
+      Agg(Deps.sourcecode) ++ maybeDataClass
+    }
+    /*def scalacOptions = T {
+      val maybeMacroAnn =
+        if (scalaVersion().startsWith("2.13."))
+          Seq("-Ymacro-annotations")
+        else
+          Nil
+      super.scalacOptions() ++ maybeMacroAnn
+    }
+    def scalacPluginIvyDeps = T {
+      if (scalaVersion().startsWith("2.12."))
+        Agg(Deps.macroParadise)
+      else
+        Agg.empty
+    }*/
+  }
+}
+
+trait CaseAppScalaJsModule extends ScalaJSModule {
+  def scalaJSVersion = Versions.scalaJs
+}
+
+trait CaseAppScalaNativeModule extends ScalaNativeModule {
+  def scalaNativeVersion = Versions.scalaNative
+}
+
+trait CaseAppPublishModule extends PublishModule {
+  import CaseAppPublishModule._
+  import mill.scalalib.publish._
+  def pomSettings = PomSettings(
+    description = artifactName(),
+    organization = "com.github.alexarchambault",
+    url = "https://github.com/alexarchambault/case-app",
+    licenses = Seq(License.`Apache-2.0`),
+    versionControl = VersionControl.github("alexarchambault", "case-app"),
+    developers = Seq(
+      Developer("alexarchambault", "Alex Archambault", "https://github.com/alexarchambault")
+    )
+  )
+  def publishVersion = T(buildVersion)
+}
+
+object CaseAppPublishModule {
+  private lazy val latestTaggedVersion =
+    os.proc("git", "describe", "--abbrev=0", "--tags", "--match", "v*")
+      .call().out
+      .trim()
+  private lazy val buildVersion = {
+    val gitHead = os.proc("git", "rev-parse", "HEAD").call().out.trim()
+    val maybeExactTag = scala.util.Try {
+      os.proc("git", "describe", "--exact-match", "--tags", "--always", gitHead)
+        .call().out
+        .trim()
+        .stripPrefix("v")
+    }
+    maybeExactTag.toOption.getOrElse {
+      val commitsSinceTaggedVersion =
+        os.proc("git", "rev-list", gitHead, "--not", latestTaggedVersion, "--count")
+          .call().out.trim()
+          .toInt
+      val gitHash = os.proc("git", "rev-parse", "--short", "HEAD").call().out.trim()
+      s"${latestTaggedVersion.stripPrefix("v")}-$commitsSinceTaggedVersion-$gitHash-SNAPSHOT"
+    }
+  }
+}
+
+object CrossSources {
+  def extraSourcesDirs(sv: String, millSourcePath: os.Path, scope: String): Seq[PathRef] = {
+    val (maj, majMin) = sv.split('.') match {
+      case Array(maj0, min, _*) => (maj0, s"$maj0.$min")
+      case _                    => sys.error(s"Malformed Scala version: $sv")
+    }
+    val baseDir = millSourcePath / os.up / "shared" / "src" / scope
+    Seq(
+      PathRef(baseDir / "scala"),
+      PathRef(baseDir / s"scala-$maj"),
+      PathRef(baseDir / s"scala-$majMin")
+    )
+  }
+}
+
+trait CrossSources extends SbtModule {
+  import CrossSources._
+  def sources = T.sources {
+    val sv = scalaVersion()
+    super.sources() ++ extraSourcesDirs(sv, millSourcePath, "main")
+  }
+}
+
+trait TestCrossSources extends SbtModule {
+  import CrossSources._
+  def sources = T.sources {
+    val sv = scalaVersion()
+    super.sources() ++ extraSourcesDirs(sv, millSourcePath, "test")
+  }
+}
+
+trait MimaChecks extends Mima {
+
+  def mimaPreviousVersions = T {
+    os.proc(
+      "git",
+      "tag",
+      "--merged",
+      "HEAD^",
+      "--contains",
+      "993ac3020db84ba06231e0268c920c9f8b9f3520"
+    )
+      .call()
+      .out.lines()
+      .map(_.trim)
+      .filter(_.startsWith("v"))
+      .map(_.stripPrefix("v"))
+  }
+
+  def mimaPreviousArtifacts = T {
+    val versions = mimaPreviousVersions().distinct
+    mill.api.Result.Success(
+      Agg.from(
+        versions.map(version =>
+          ivy"${pomSettings().organization}:${artifactId()}:$version"
+        )
+      )
+    )
+  }
+}
+
+object ci extends Module {
+
+  def publishSonatype(tasks: mill.main.Tasks[PublishModule.PublishData]) = T.command {
+    publishSonatype0(
+      data = define.Target.sequence(tasks.value)(),
+      log = T.ctx().log
+    )
+  }
+
+  def publishSonatype0(
+    data: Seq[PublishModule.PublishData],
+    log: mill.api.Logger
+  ): Unit = {
+
+    val credentials = sys.env("SONATYPE_USERNAME") + ":" + sys.env("SONATYPE_PASSWORD")
+    val pgpPassword = sys.env("PGP_PASSPHRASE")
+    val timeout     = 10.minutes
+
+    val artifacts = data.map {
+      case PublishModule.PublishData(a, s) =>
+        (s.map { case (p, f) => (p.path, f) }, a)
+    }
+
+    val isRelease = {
+      val versions = artifacts.map(_._2.version).toSet
+      val set      = versions.map(!_.endsWith("-SNAPSHOT"))
+      assert(
+        set.size == 1,
+        s"Found both snapshot and non-snapshot versions: ${versions.toVector.sorted.mkString(", ")}"
+      )
+      set.head
+    }
+    val publisher = new scalalib.publish.SonatypePublisher(
+      uri = "https://oss.sonatype.org/service/local",
+      snapshotUri = "https://oss.sonatype.org/content/repositories/snapshots",
+      credentials = credentials,
+      signed = true,
+      // format: off
+      gpgArgs = Seq(
+        "--detach-sign",
+        "--batch=true",
+        "--yes",
+        "--pinentry-mode", "loopback",
+        "--passphrase", pgpPassword,
+        "--armor",
+        "--use-agent"
+      ),
+      // format: on
+      readTimeout = timeout.toMillis.toInt,
+      connectTimeout = timeout.toMillis.toInt,
+      log = log,
+      awaitTimeout = timeout.toMillis.toInt,
+      stagingRelease = isRelease
+    )
+
+    publisher.publishAll(isRelease, artifacts: _*)
+  }
+
+}
diff --git a/mill b/mill
new file mode 100755
index 00000000..c4157ae6
--- /dev/null
+++ b/mill
@@ -0,0 +1,206 @@
+#!/usr/bin/env sh
+
+# This is a wrapper script, that automatically download mill from GitHub release pages
+# You can give the required mill version with --mill-version parameter
+# If no version is given, it falls back to the value of DEFAULT_MILL_VERSION
+#
+# Project page: https://github.com/lefou/millw
+# Script Version: 0.4.7
+#
+# If you want to improve this script, please also contribute your changes back!
+#
+# Licensed under the Apache License, Version 2.0
+
+set -e
+
+if [ -z "${DEFAULT_MILL_VERSION}" ] ; then
+  DEFAULT_MILL_VERSION="0.11.0"
+fi
+
+
+if [ -z "${GITHUB_RELEASE_CDN}" ] ; then
+  GITHUB_RELEASE_CDN=""
+fi
+
+
+MILL_REPO_URL="https://github.com/com-lihaoyi/mill"
+
+if [ -z "${CURL_CMD}" ] ; then
+  CURL_CMD=curl
+fi
+
+# Explicit commandline argument takes precedence over all other methods
+if [ "$1" = "--mill-version" ] ; then
+  shift
+  if [ "x$1" != "x" ] ; then
+    MILL_VERSION="$1"
+    shift
+  else
+    echo "You specified --mill-version without a version." 1>&2
+    echo "Please provide a version that matches one provided on" 1>&2
+    echo "${MILL_REPO_URL}/releases" 1>&2
+    false
+  fi
+fi
+
+# Please note, that if a MILL_VERSION is already set in the environment,
+# We reuse it's value and skip searching for a value.
+
+# If not already set, read .mill-version file
+if [ -z "${MILL_VERSION}" ] ; then
+  if [ -f ".mill-version" ] ; then
+    MILL_VERSION="$(head -n 1 .mill-version 2> /dev/null)"
+  elif [ -f ".config/mill-version" ] ; then
+    MILL_VERSION="$(head -n 1 .config/mill-version 2> /dev/null)"
+  fi
+fi
+
+if [ -z "${MILL_DOWNLOAD_PATH}" ] ; then
+  if [ -n "${XDG_CACHE_HOME}" ] ; then
+    MILL_DOWNLOAD_PATH="${XDG_CACHE_HOME}/mill/download"
+  else
+    MILL_DOWNLOAD_PATH="${HOME}/.cache/mill/download"
+  fi
+fi
+
+# If not already set, try to fetch newest from Github
+if [ -z "${MILL_VERSION}" ] ; then
+  # TODO: try to load latest version from release page
+  echo "No mill version specified." 1>&2
+  echo "You should provide a version via '.mill-version' file or --mill-version option." 1>&2
+
+  mkdir -p "${MILL_DOWNLOAD_PATH}"
+  LANG=C touch -d '1 hour ago' "${MILL_DOWNLOAD_PATH}/.expire_latest" 2>/dev/null || (
+    # we might be on OSX or BSD which don't have -d option for touch
+    # but probably a -A [-][[hh]mm]SS
+    touch "${MILL_DOWNLOAD_PATH}/.expire_latest"; touch -A -010000 "${MILL_DOWNLOAD_PATH}/.expire_latest"
+  ) || (
+    # in case we still failed, we retry the first touch command with the intention
+    # to show the (previously suppressed) error message
+    LANG=C touch -d '1 hour ago' "${MILL_DOWNLOAD_PATH}/.expire_latest"
+  )
+
+  # POSIX shell variant of bash's -nt operator, see https://unix.stackexchange.com/a/449744/6993
+  # if [ "${MILL_DOWNLOAD_PATH}/.latest" -nt "${MILL_DOWNLOAD_PATH}/.expire_latest" ] ; then
+  if [ -n "$(find -L "${MILL_DOWNLOAD_PATH}/.latest" -prune -newer "${MILL_DOWNLOAD_PATH}/.expire_latest")" ]; then
+    # we know a current latest version
+    MILL_VERSION=$(head -n 1 "${MILL_DOWNLOAD_PATH}"/.latest 2> /dev/null)
+  fi
+
+  if [ -z "${MILL_VERSION}" ] ; then
+    # we don't know a current latest version
+    echo "Retrieving latest mill version ..." 1>&2
+    LANG=C ${CURL_CMD} -s -i -f -I ${MILL_REPO_URL}/releases/latest 2> /dev/null  | grep --ignore-case Location: | sed s'/^.*tag\///' | tr -d '\r\n' > "${MILL_DOWNLOAD_PATH}/.latest"
+    MILL_VERSION=$(head -n 1 "${MILL_DOWNLOAD_PATH}"/.latest 2> /dev/null)
+  fi
+
+  if [ -z "${MILL_VERSION}" ] ; then
+    # Last resort
+    MILL_VERSION="${DEFAULT_MILL_VERSION}"
+    echo "Falling back to hardcoded mill version ${MILL_VERSION}" 1>&2
+  else
+    echo "Using mill version ${MILL_VERSION}" 1>&2
+  fi
+fi
+
+MILL="${MILL_DOWNLOAD_PATH}/${MILL_VERSION}"
+
+try_to_use_system_mill() {
+  MILL_IN_PATH="$(command -v mill || true)"
+
+  if [ -z "${MILL_IN_PATH}" ]; then
+    return
+  fi
+
+  UNIVERSAL_SCRIPT_MAGIC="@ 2>/dev/null # 2>nul & echo off & goto BOF"
+
+  if ! head -c 128 "${MILL_IN_PATH}" | grep -qF "${UNIVERSAL_SCRIPT_MAGIC}"; then
+    if [ -n "${MILLW_VERBOSE}" ]; then
+      echo "Could not determine mill version of ${MILL_IN_PATH}, as it does not start with the universal script magic2" 1>&2
+    fi
+    return
+  fi
+
+  # Roughly the size of the universal script.
+  MILL_VERSION_SEARCH_RANGE="2403"
+  MILL_IN_PATH_VERSION=$(head -c "${MILL_VERSION_SEARCH_RANGE}" "${MILL_IN_PATH}" |\
+                         sed -n 's/^.*-DMILL_VERSION=\([^\s]*\) .*$/\1/p' |\
+                         head -n 1)
+
+  if [ -z "${MILL_IN_PATH_VERSION}" ]; then
+    echo "Could not determine mill version, even though ${MILL_IN_PATH} has the universal script magic" 1>&2
+    return
+  fi
+
+  if [ "${MILL_IN_PATH_VERSION}" = "${MILL_VERSION}" ]; then
+    MILL="${MILL_IN_PATH}"
+  fi
+}
+try_to_use_system_mill
+
+# If not already downloaded, download it
+if [ ! -s "${MILL}" ] ; then
+
+  # support old non-XDG download dir
+  MILL_OLD_DOWNLOAD_PATH="${HOME}/.mill/download"
+  OLD_MILL="${MILL_OLD_DOWNLOAD_PATH}/${MILL_VERSION}"
+  if [ -x "${OLD_MILL}" ] ; then
+    MILL="${OLD_MILL}"
+  else
+    case $MILL_VERSION in
+      0.0.* | 0.1.* | 0.2.* | 0.3.* | 0.4.* )
+        DOWNLOAD_SUFFIX=""
+        DOWNLOAD_FROM_MAVEN=0
+        ;;
+      0.5.* | 0.6.* | 0.7.* | 0.8.* | 0.9.* | 0.10.* | 0.11.0-M* )
+        DOWNLOAD_SUFFIX="-assembly"
+        DOWNLOAD_FROM_MAVEN=0
+        ;;
+      *)
+        DOWNLOAD_SUFFIX="-assembly"
+        DOWNLOAD_FROM_MAVEN=1
+        ;;
+    esac
+
+    DOWNLOAD_FILE=$(mktemp mill.XXXXXX)
+
+    if [ "$DOWNLOAD_FROM_MAVEN" = "1" ] ; then
+      DOWNLOAD_URL="https://repo1.maven.org/maven2/com/lihaoyi/mill-dist/${MILL_VERSION}/mill-dist-${MILL_VERSION}.jar"
+    else
+      MILL_VERSION_TAG=$(echo $MILL_VERSION | sed -E 's/([^-]+)(-M[0-9]+)?(-.*)?/\1\2/')
+      DOWNLOAD_URL="${GITHUB_RELEASE_CDN}${MILL_REPO_URL}/releases/download/${MILL_VERSION_TAG}/${MILL_VERSION}${DOWNLOAD_SUFFIX}"
+      unset MILL_VERSION_TAG
+    fi
+
+    # TODO: handle command not found
+    echo "Downloading mill ${MILL_VERSION} from ${DOWNLOAD_URL} ..." 1>&2
+    ${CURL_CMD} -f -L -o "${DOWNLOAD_FILE}" "${DOWNLOAD_URL}"
+    chmod +x "${DOWNLOAD_FILE}"
+    mkdir -p "${MILL_DOWNLOAD_PATH}"
+    mv "${DOWNLOAD_FILE}" "${MILL}"
+
+    unset DOWNLOAD_FILE
+    unset DOWNLOAD_SUFFIX
+  fi
+fi
+
+if [ -z "$MILL_MAIN_CLI" ] ; then
+  MILL_MAIN_CLI="${0}"
+fi
+
+MILL_FIRST_ARG=""
+if [ "$1" = "--bsp" ] || [ "$1" = "-i" ] || [ "$1" = "--interactive" ] || [ "$1" = "--no-server" ] || [ "$1" = "--repl" ] || [ "$1" = "--help" ] ; then
+  # Need to preserve the first position of those listed options
+  MILL_FIRST_ARG=$1
+  shift
+fi
+
+unset MILL_DOWNLOAD_PATH
+unset MILL_OLD_DOWNLOAD_PATH
+unset OLD_MILL
+unset MILL_VERSION
+unset MILL_REPO_URL
+
+# We don't quote MILL_FIRST_ARG on purpose, so we can expand the empty value without quotes
+# shellcheck disable=SC2086
+exec "${MILL}" $MILL_FIRST_ARG -D "mill.main.cli=${MILL_MAIN_CLI}" "$@"
diff --git a/mill.bat b/mill.bat
new file mode 100644
index 00000000..bec5bd46
--- /dev/null
+++ b/mill.bat
@@ -0,0 +1,220 @@
+@echo off
+
+rem This is a wrapper script, that automatically download mill from GitHub release pages
+rem You can give the required mill version with --mill-version parameter
+rem If no version is given, it falls back to the value of DEFAULT_MILL_VERSION
+rem
+rem Project page: https://github.com/lefou/millw
+rem Script Version: 0.4.7
+rem
+rem If you want to improve this script, please also contribute your changes back!
+rem
+rem Licensed under the Apache License, Version 2.0
+
+rem setlocal seems to be unavailable on Windows 95/98/ME
+rem but I don't think we need to support them in 2019
+setlocal enabledelayedexpansion
+
+if [!DEFAULT_MILL_VERSION!]==[] (
+    set "DEFAULT_MILL_VERSION=0.11.0"
+)
+
+if [!GITHUB_RELEASE_CDN!]==[] (
+    set "GITHUB_RELEASE_CDN="
+)
+
+set "MILL_REPO_URL=https://github.com/com-lihaoyi/mill"
+
+rem %~1% removes surrounding quotes
+if [%~1%]==[--mill-version] (
+  if not [%~2%]==[] (
+    set MILL_VERSION=%~2%
+    rem shift command doesn't work within parentheses
+    set "STRIP_VERSION_PARAMS=true"
+  ) else (
+    echo You specified --mill-version without a version. 1>&2
+    echo Please provide a version that matches one provided on 1>&2
+    echo %MILL_REPO_URL%/releases 1>&2
+    exit /b 1
+  )
+)
+
+if not defined STRIP_VERSION_PARAMS GOTO AfterStripVersionParams
+rem strip the: --mill-version {version}
+shift
+shift
+:AfterStripVersionParams
+
+if [!MILL_VERSION!]==[] (
+  if exist .mill-version (
+      set /p MILL_VERSION=<.mill-version
+  ) else (
+    if exist .config\mill-version (
+      set /p MILL_VERSION=<.config\mill-version
+    )
+  )
+)
+
+if [!MILL_VERSION!]==[] (
+    set MILL_VERSION=%DEFAULT_MILL_VERSION%
+)
+
+if [!MILL_DOWNLOAD_PATH!]==[] (
+    set MILL_DOWNLOAD_PATH=%USERPROFILE%\.mill\download
+)
+
+rem without bat file extension, cmd doesn't seem to be able to run it
+set MILL=%MILL_DOWNLOAD_PATH%\!MILL_VERSION!.bat
+
+if not exist "%MILL%" (
+    set VERSION_PREFIX=%MILL_VERSION:~0,4%
+    # Since 0.5.0
+    set DOWNLOAD_SUFFIX=-assembly
+    # Since 0.11.0
+    set DOWNLOAD_FROM_MAVEN=1
+    if [!VERSION_PREFIX!]==[0.0.] (
+        set DOWNLOAD_SUFFIX=
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.1.] (
+        set DOWNLOAD_SUFFIX=
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.2.] (
+        set DOWNLOAD_SUFFIX=
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.3.] (
+        set DOWNLOAD_SUFFIX=
+        set DOWNLOAD_FROM_MAVEN=0
+   )
+    if [!VERSION_PREFIX!]==[0.4.] (
+        set DOWNLOAD_SUFFIX=
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.5.] (
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.6.] (
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.7.] (
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.8.] (
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    if [!VERSION_PREFIX!]==[0.9.] (
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    set VERSION_PREFIX=%MILL_VERSION:~0,5%
+    if [!VERSION_PREFIX!]==[0.10.] (
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    set VERSION_PREFIX=%MILL_VERSION:~0,8%
+    if [!VERSION_PREFIX!]==[0.11.0-M] (
+        set DOWNLOAD_FROM_MAVEN=0
+    )
+    set VERSION_PREFIX=
+
+    for /F "delims=- tokens=1" %%A in ("!MILL_VERSION!") do set MILL_VERSION_BASE=%%A
+    for /F "delims=- tokens=2" %%A in ("!MILL_VERSION!") do set MILL_VERSION_MILESTONE=%%A
+	set VERSION_MILESTONE_START=!MILL_VERSION_MILESTONE:~0,1!
+    if [!VERSION_MILESTONE_START!]==[M] (
+        set MILL_VERSION_TAG="!MILL_VERSION_BASE!-!MILL_VERSION_MILESTONE!"
+    ) else (
+        set MILL_VERSION_TAG=!MILL_VERSION_BASE!
+    )
+
+    rem there seems to be no way to generate a unique temporary file path (on native Windows)
+    set DOWNLOAD_FILE=%MILL%.tmp
+
+    if [!DOWNLOAD_FROM_MAVEN]==[1] (
+        set DOWNLOAD_URL=https://repo1.maven.org/maven2/com/lihaoyi/mill-dist/!MILL_VERSION!/mill-dist-!MILL_VERSION!.jar
+    ) else (
+        set DOWNLOAD_URL=!GITHUB_RELEASE_CDN!%MILL_REPO_URL%/releases/download/!MILL_VERSION_TAG!/!MILL_VERSION!!DOWNLOAD_SUFFIX!
+    )
+
+    echo Downloading mill %MILL_VERSION% from !DOWNLOAD_URL! ... 1>&2
+
+    if not exist "%MILL_DOWNLOAD_PATH%" mkdir "%MILL_DOWNLOAD_PATH%"
+    rem curl is bundled with recent Windows 10
+    rem but I don't think we can expect all the users to have it in 2019
+    where /Q curl
+    if %ERRORLEVEL% EQU 0 (
+        curl -f -L "!DOWNLOAD_URL!" -o "!DOWNLOAD_FILE!"
+    ) else (
+        rem bitsadmin seems to be available on Windows 7
+        rem without /dynamic, github returns 403
+        rem bitsadmin is sometimes needlessly slow but it looks better with /priority foreground
+        bitsadmin /transfer millDownloadJob /dynamic /priority foreground "!DOWNLOAD_URL!" "!DOWNLOAD_FILE!"
+    )
+    if not exist "!DOWNLOAD_FILE!" (
+        echo Could not download mill %MILL_VERSION% 1>&2
+        exit /b 1
+    )
+
+    move /y "!DOWNLOAD_FILE!" "%MILL%"
+
+    set DOWNLOAD_FILE=
+    set DOWNLOAD_SUFFIX=
+)
+
+set MILL_DOWNLOAD_PATH=
+set MILL_VERSION=
+set MILL_REPO_URL=
+
+if [!MILL_MAIN_CLI!]==[] (
+    set "MILL_MAIN_CLI=%0"
+)
+
+rem Need to preserve the first position of those listed options
+set MILL_FIRST_ARG=
+if [%~1%]==[--bsp] (
+  set MILL_FIRST_ARG=%1%
+) else (
+  if [%~1%]==[-i] (
+    set MILL_FIRST_ARG=%1%
+  ) else (
+    if [%~1%]==[--interactive] (
+      set MILL_FIRST_ARG=%1%
+    ) else (
+      if [%~1%]==[--no-server] (
+        set MILL_FIRST_ARG=%1%
+      ) else (
+        if [%~1%]==[--repl] (
+          set MILL_FIRST_ARG=%1%
+        ) else (
+          if [%~1%]==[--help] (
+            set MILL_FIRST_ARG=%1%
+          )
+        )
+      )
+    )
+  )
+)
+
+set "MILL_PARAMS=%*%"
+
+if not [!MILL_FIRST_ARG!]==[] (
+  if defined STRIP_VERSION_PARAMS (
+    for /f "tokens=1-3*" %%a in ("%*") do (
+        set "MILL_PARAMS=%%d"
+    )
+  ) else (
+    for /f "tokens=1*" %%a in ("%*") do (
+      set "MILL_PARAMS=%%b"
+    )
+  )
+) else (
+  if defined STRIP_VERSION_PARAMS (
+    for /f "tokens=1-2*" %%a in ("%*") do (
+        rem strip %%a - It's the "--mill-version" option.
+        rem strip %%b - it's the version number that comes after the option.
+        rem keep  %%c - It's the remaining options.
+        set "MILL_PARAMS=%%c"
+    )
+  )
+)
+
+"%MILL%" %MILL_FIRST_ARG% -D "mill.main.cli=%MILL_MAIN_CLI%" %MILL_PARAMS%
diff --git a/project/Deps.scala b/project/Deps.scala
deleted file mode 100644
index 7d0c843b..00000000
--- a/project/Deps.scala
+++ /dev/null
@@ -1,21 +0,0 @@
-import sbt._
-import sbt.Keys._
-
-import org.portablescala.sbtplatformdeps.PlatformDepsPlugin.autoImport._
-
-object Deps {
-
-  import Def.setting
-
-  def catsEffect2   = setting("org.typelevel" %%% "cats-effect" % "2.5.5")
-  def catsEffect3   = setting("org.typelevel" %%% "cats-effect" % "3.5.4")
-  def dataClass     = "io.github.alexarchambault" %% "data-class" % "0.2.6"
-  def macroParadise = "org.scalamacros"            % "paradise"   % "2.1.1" cross CrossVersion.patch
-  def pprint        = setting("com.lihaoyi" %%% "pprint" % "0.9.0")
-  def scalaCompiler = setting("org.scala-lang" % "scala-compiler" % scalaVersion.value)
-  def scalaReflect  = setting("org.scala-lang" % "scala-reflect" % scalaVersion.value)
-  def shapeless     = setting("com.chuusai" %%% "shapeless" % "2.3.12")
-  def sourcecode    = setting("com.lihaoyi" %%% "sourcecode" % "0.4.2")
-  def utest         = setting("com.lihaoyi" %%% "utest" % "0.8.3")
-
-}
diff --git a/project/Mima.scala b/project/Mima.scala
deleted file mode 100644
index e5000f07..00000000
--- a/project/Mima.scala
+++ /dev/null
@@ -1,29 +0,0 @@
-import com.typesafe.tools.mima.core._
-import com.typesafe.tools.mima.plugin.MimaPlugin
-import sbt._
-import sbt.Keys._
-
-import scala.sys.process._
-
-object Mima {
-
-  def binaryCompatibilityVersions: Set[String] =
-    Seq("git", "tag", "--merged", "HEAD^", "--contains", "993ac3020db84ba06231e0268c920c9f8b9f3520")
-      .!!
-      .linesIterator
-      .map(_.trim)
-      .filter(_.startsWith("v"))
-      .map(_.stripPrefix("v"))
-      .toSet
-
-  def settings = Def.settings(
-    MimaPlugin.autoImport.mimaPreviousArtifacts := {
-      binaryCompatibilityVersions
-        .map { ver =>
-          (organization.value % moduleName.value % ver)
-            .cross(crossVersion.value)
-        }
-    }
-  )
-
-}
diff --git a/project/Settings.scala b/project/Settings.scala
deleted file mode 100644
index ee0dbf42..00000000
--- a/project/Settings.scala
+++ /dev/null
@@ -1,49 +0,0 @@
-import sbt._
-import sbt.Keys._
-
-object Settings {
-
-  private def scala212 = "2.12.19"
-  private def scala213 = "2.13.14"
-  private def scala3   = "3.3.3"
-
-  private lazy val isAtLeastScala213 = Def.setting {
-    import Ordering.Implicits._
-    CrossVersion.partialVersion(scalaVersion.value).exists(_ >= (2, 13))
-  }
-
-  lazy val shared = Seq(
-    scalaVersion       := scala3,
-    crossScalaVersions := Seq(scala212, scala213, scala3),
-    scalacOptions ++= Seq(
-      "-target:jvm-1.8",
-      "-feature",
-      "-deprecation"
-    ),
-    libraryDependencies ++= {
-      CrossVersion.partialVersion(scalaVersion.value) match {
-        case Some((2, v)) if v <= 12 =>
-          compilerPlugin(Deps.macroParadise) :: Nil
-        case _ =>
-          // if scala 2.13.0-M4 or later, macro annotations merged into scala-reflect
-          // https://github.com/scala/scala/pull/6606
-          Nil
-      }
-    },
-    scalacOptions ++= {
-      if (isAtLeastScala213.value) Seq("-Ymacro-annotations")
-      else Nil
-    },
-    autoAPIMappings := true
-  )
-
-  lazy val caseAppPrefix =
-    name := {
-      val shortenedName = name.value
-        .stripSuffix("JVM")
-        .stripSuffix("JS")
-        .stripSuffix("Native")
-      "case-app-" + shortenedName
-    }
-
-}
diff --git a/project/build.properties b/project/build.properties
deleted file mode 100644
index 04267b14..00000000
--- a/project/build.properties
+++ /dev/null
@@ -1 +0,0 @@
-sbt.version=1.9.9
diff --git a/project/plugins.sbt b/project/plugins.sbt
deleted file mode 100644
index e5378c07..00000000
--- a/project/plugins.sbt
+++ /dev/null
@@ -1,7 +0,0 @@
-addSbtPlugin("com.thoughtworks.sbt-api-mappings" % "sbt-api-mappings"              % "3.0.2")
-addSbtPlugin("com.github.sbt"                    % "sbt-ci-release"                % "1.5.12")
-addSbtPlugin("com.typesafe"                      % "sbt-mima-plugin"               % "1.1.3")
-addSbtPlugin("org.scala-js"                      % "sbt-scalajs"                   % "1.16.0")
-addSbtPlugin("org.portable-scala"                % "sbt-scalajs-crossproject"      % "1.3.2")
-addSbtPlugin("org.scala-native"                  % "sbt-scala-native"              % "0.5.2")
-addSbtPlugin("org.portable-scala"                % "sbt-scala-native-crossproject" % "1.3.2")