DamianReeves · March 14, 2026 18:05
diff --git a/.gitignore b/.gitignore
 .metals/
 .bsp/
 target/
 .idea/
 out/
 .vscode/
 .scala-build/
 dist/
diff --git a/README.md b/README.md
diff --git a/build.mill b/build.mill
 //| mill-version: 1.1.3
 package build

 import mill._
 import mill.api._
 import mill.scalalib._
 import mill.javalib._
 import scala.util.Properties

 /** Echo app: native image from Echo.scala (same config as script headers). */
 object echo extends ScalaModule with NativeImageModule {
  def scalaVersion   = "3.8.2"
  def millSourcePath = mill.api.BuildCtx.workspaceRoot
  override def sources = Task.Sources(millSourcePath / "Echo.scala")
  def mainClass = Some("Echo")
  def jvmVersion = "graalvm-java25:25.0.1"
  def nativeImageOptions = Task { Seq("--no-fallback") }
 }

 /** Publish native image to output-dir/echo-mill (default: dist). Triggers echo.nativeImage then copies. */
 def dist(outputDir: String = "dist") = Task.Command {
  val out    = echo.nativeImage()
  val ext    = if (Properties.isWin) ".exe" else ""
  val destDir = mill.api.BuildCtx.workspaceRoot / outputDir
  val dest   = destDir / s"echo-mill$ext"
  os.makeDir.all(destDir)
  os.copy.over(out.path, dest)
  Task.log.info(s"Published to $dest")
 }
diff --git a/Echo.scala b/Echo.scala
 //| scalaVersion: 3.8.2
 //| jvmVersion: "graalvm-java25:25.0.1"
 //| nativeImageOptions: ["--no-fallback"]
 //> using scala "3.8.2"
 //> using jvm "graalvm-java25:25.0.1"
 //> using packaging.packageType "graalvm"
 //> using packaging.output "echo"
 //> using packaging.graalvmArgs "--no-fallback"

 object Echo:
    def main(args: Array[String]): Unit =
        println(args.mkString(" "))
diff --git a/mill b/mill
 #!/usr/bin/env sh

 set -e

 if [ -z "${DEFAULT_MILL_VERSION}" ] ; then DEFAULT_MILL_VERSION="1.1.3"; fi

 if [ -z "${GITHUB_RELEASE_CDN}" ] ; then GITHUB_RELEASE_CDN=""; fi

 if [ -z "$MILL_MAIN_CLI" ] ; then MILL_MAIN_CLI="${0}"; fi

 MILL_REPO_URL="https://github.com/com-lihaoyi/mill"

 MILL_BUILD_SCRIPT=""

 if [ -f "build.mill" ] ; then
  MILL_BUILD_SCRIPT="build.mill"
 elif [ -f "build.mill.scala" ] ; then
  MILL_BUILD_SCRIPT="build.mill.scala"
 elif [ -f "build.sc" ] ; then
  MILL_BUILD_SCRIPT="build.sc"
 fi

 # `s/.*://`:
 #   This is a greedy match that removes everything from the beginning of the line up to (and including) the last
 #   colon (:). This effectively isolates the value part of the declaration.
 #
 #  `s/#.*//`:
 #    This removes any comments at the end of the line.
 #
 #  `s/['\"]//g`:
 #    This removes all single and double quotes from the string, wherever they appear (g is for "global").
 #
 #  `s/^[[:space:]]*//; s/[[:space:]]*$//`:
 #    These two expressions trim any leading or trailing whitespace ([[:space:]] matches spaces and tabs).
 TRIM_VALUE_SED="s/.*://; s/#.*//; s/['\"]//g; s/^[[:space:]]*//; s/[[:space:]]*$//"

 if [ -z "${MILL_VERSION}" ] ; then
  if [ -f ".mill-version" ] ; then
    MILL_VERSION="$(tr '\r' '\n' < .mill-version | head -n 1 2> /dev/null)"
  elif [ -f ".config/mill-version" ] ; then
    MILL_VERSION="$(tr '\r' '\n' < .config/mill-version | head -n 1 2> /dev/null)"
  elif [ -f "build.mill.yaml" ] ; then
    MILL_VERSION="$(grep -E "mill-version:" "build.mill.yaml" | sed -E "$TRIM_VALUE_SED")"
  elif [ -n "${MILL_BUILD_SCRIPT}" ] ; then
    MILL_VERSION="$(grep -E "//\|.*mill-version" "${MILL_BUILD_SCRIPT}" | sed -E "$TRIM_VALUE_SED")"
  fi
 fi

 if [ -z "${MILL_VERSION}" ] ; then MILL_VERSION="${DEFAULT_MILL_VERSION}"; fi

 MILL_USER_CACHE_DIR="${XDG_CACHE_HOME:-${HOME}/.cache}/mill"

 if [ -z "${MILL_FINAL_DOWNLOAD_FOLDER}" ] ; then MILL_FINAL_DOWNLOAD_FOLDER="${MILL_USER_CACHE_DIR}/download"; fi

 MILL_NATIVE_SUFFIX="-native"
 MILL_JVM_SUFFIX="-jvm"
 ARTIFACT_SUFFIX=""

 # Check if GLIBC version is at least the required version
 # Returns 0 (true) if GLIBC >= required version, 1 (false) otherwise
 check_glibc_version() {
  required_version="2.39"
  required_major=$(echo "$required_version" | cut -d. -f1)
  required_minor=$(echo "$required_version" | cut -d. -f2)
  # Get GLIBC version from ldd --version (first line contains version like "ldd (GNU libc) 2.31")
  glibc_version=$(ldd --version 2>/dev/null | head -n 1 | grep -oE '[0-9]+\.[0-9]+$' || echo "")
  if [ -z "$glibc_version" ]; then
    # If we can't determine GLIBC version, assume it's too old
    return 1
  fi
  glibc_major=$(echo "$glibc_version" | cut -d. -f1)
  glibc_minor=$(echo "$glibc_version" | cut -d. -f2)
  if [ "$glibc_major" -gt "$required_major" ]; then
    return 0
  elif [ "$glibc_major" -eq "$required_major" ] && [ "$glibc_minor" -ge "$required_minor" ]; then
    return 0
  else
    return 1
  fi
 }

 set_artifact_suffix() {
  if [ "$(uname -s 2>/dev/null | cut -c 1-5)" = "Linux" ]; then
    # Native binaries require new enough GLIBC; fall back to JVM launcher if older
    if ! check_glibc_version; then
      return
    fi
    if [ "$(uname -m)" = "aarch64" ]; then ARTIFACT_SUFFIX="-native-linux-aarch64"
    else ARTIFACT_SUFFIX="-native-linux-amd64"; fi
  elif [ "$(uname)" = "Darwin" ]; then
    if [ "$(uname -m)" = "arm64" ]; then ARTIFACT_SUFFIX="-native-mac-aarch64"
    else ARTIFACT_SUFFIX="-native-mac-amd64"; fi
  else
    echo "This native mill launcher supports only Linux and macOS." 1>&2
    exit 1
  fi
 }

 case "$MILL_VERSION" in
  *"$MILL_NATIVE_SUFFIX")
    MILL_VERSION=${MILL_VERSION%"$MILL_NATIVE_SUFFIX"}
    set_artifact_suffix
    ;;

  *"$MILL_JVM_SUFFIX")
    MILL_VERSION=${MILL_VERSION%"$MILL_JVM_SUFFIX"}
    ;;

  *)
    case "$MILL_VERSION" in
      0.1.* | 0.2.* | 0.3.* | 0.4.* | 0.5.* | 0.6.* | 0.7.* | 0.8.* | 0.9.* | 0.10.* | 0.11.* | 0.12.*)
        ;;
      *)
        set_artifact_suffix
        ;;
    esac
    ;;
 esac

 MILL="${MILL_FINAL_DOWNLOAD_FOLDER}/$MILL_VERSION$ARTIFACT_SUFFIX"

 # If not already downloaded, download it
 if [ ! -s "${MILL}" ] || [ "$MILL_TEST_DRY_RUN_LAUNCHER_SCRIPT" = "1" ] ; then
  case $MILL_VERSION in
    0.0.* | 0.1.* | 0.2.* | 0.3.* | 0.4.*)
      MILL_DOWNLOAD_SUFFIX=""
      MILL_DOWNLOAD_FROM_MAVEN=0
      ;;
    0.5.* | 0.6.* | 0.7.* | 0.8.* | 0.9.* | 0.10.* | 0.11.0-M*)
      MILL_DOWNLOAD_SUFFIX="-assembly"
      MILL_DOWNLOAD_FROM_MAVEN=0
      ;;
    *)
      MILL_DOWNLOAD_SUFFIX="-assembly"
      MILL_DOWNLOAD_FROM_MAVEN=1
      ;;
  esac
  case $MILL_VERSION in
    0.12.0 | 0.12.1 | 0.12.2 | 0.12.3 | 0.12.4 | 0.12.5 | 0.12.6 | 0.12.7 | 0.12.8 | 0.12.9 | 0.12.10 | 0.12.11)
      MILL_DOWNLOAD_EXT="jar"
      ;;
    0.12.*)
      MILL_DOWNLOAD_EXT="exe"
      ;;
    0.*)
      MILL_DOWNLOAD_EXT="jar"
      ;;
    *)
      MILL_DOWNLOAD_EXT="exe"
      ;;
  esac

  MILL_TEMP_DOWNLOAD_FILE="${MILL_OUTPUT_DIR:-out}/mill-temp-download"
  mkdir -p "$(dirname "${MILL_TEMP_DOWNLOAD_FILE}")"

  if [ "$MILL_DOWNLOAD_FROM_MAVEN" = "1" ] ; then
    MILL_DOWNLOAD_URL="https://repo1.maven.org/maven2/com/lihaoyi/mill-dist${ARTIFACT_SUFFIX}/${MILL_VERSION}/mill-dist${ARTIFACT_SUFFIX}-${MILL_VERSION}.${MILL_DOWNLOAD_EXT}"
  else
    MILL_VERSION_TAG=$(echo "$MILL_VERSION" | sed -E 's/([^-]+)(-M[0-9]+)?(-.*)?/\1\2/')
    MILL_DOWNLOAD_URL="${GITHUB_RELEASE_CDN}${MILL_REPO_URL}/releases/download/${MILL_VERSION_TAG}/${MILL_VERSION}${MILL_DOWNLOAD_SUFFIX}"
    unset MILL_VERSION_TAG
  fi


  if [ "$MILL_TEST_DRY_RUN_LAUNCHER_SCRIPT" = "1" ] ; then
    echo "$MILL_DOWNLOAD_URL"
    echo "$MILL"
    exit 0
  fi

  echo "Downloading mill ${MILL_VERSION} from ${MILL_DOWNLOAD_URL} ..." 1>&2
  curl -f -L -o "${MILL_TEMP_DOWNLOAD_FILE}" "${MILL_DOWNLOAD_URL}"

  chmod +x "${MILL_TEMP_DOWNLOAD_FILE}"

  mkdir -p "${MILL_FINAL_DOWNLOAD_FOLDER}"
  mv "${MILL_TEMP_DOWNLOAD_FILE}" "${MILL}"

  unset MILL_TEMP_DOWNLOAD_FILE
  unset MILL_DOWNLOAD_SUFFIX
 fi

 MILL_FIRST_ARG=""
 if [ "$1" = "--bsp" ] || [ "${1#"-i"}" != "$1" ] || [ "$1" = "--interactive" ] || [ "$1" = "--no-server" ] || [ "$1" = "--no-daemon" ] || [ "$1" = "--help" ] ; then
  # Need to preserve the first position of those listed options
  MILL_FIRST_ARG=$1
  shift
 fi

 unset MILL_FINAL_DOWNLOAD_FOLDER
 unset MILL_OLD_DOWNLOAD_PATH
 unset OLD_MILL
 unset MILL_VERSION
 unset MILL_REPO_URL

 # -D mill.main.cli is for compatibility with Mill 0.10.9 - 0.13.0-M2
 # 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}" "$@"
Goal	Command
Run on JVM	`./mill echo.run -- <args>`
Build native image (in `out/echo/nativeImage.dest/`)	`./mill echo.nativeImage`
Build and publish to `dist/echo-mill`	`./mill dist`
Publish to a custom directory	`./mill dist --output-dir <dir>`
Run published binary	`./dist/echo-mill <args>`
Goal	Command
Run on JVM	`scala-cli run .`
Build native image	`scala-cli --power package . -o echo`
	//\| mill-version: 1.1.3
	package build

	import mill._
	import mill.api._
	import mill.scalalib._
	import mill.javalib._
	import scala.util.Properties

	/** Echo app: native image from Echo.scala (same config as script headers). */
	object echo extends ScalaModule with NativeImageModule {
	def scalaVersion = "3.8.2"
	def millSourcePath = mill.api.BuildCtx.workspaceRoot
	override def sources = Task.Sources(millSourcePath / "Echo.scala")
	def mainClass = Some("Echo")
	def jvmVersion = "graalvm-java25:25.0.1"
	def nativeImageOptions = Task { Seq("--no-fallback") }
	}

	/** Publish native image to output-dir/echo-mill (default: dist). Triggers echo.nativeImage then copies. */
	def dist(outputDir: String = "dist") = Task.Command {
	val out = echo.nativeImage()
	val ext = if (Properties.isWin) ".exe" else ""
	val destDir = mill.api.BuildCtx.workspaceRoot / outputDir
	val dest = destDir / s"echo-mill$ext"
	os.makeDir.all(destDir)
	os.copy.over(out.path, dest)
	Task.log.info(s"Published to $dest")
	}
	//\| scalaVersion: 3.8.2
	//\| jvmVersion: "graalvm-java25:25.0.1"
	//\| nativeImageOptions: ["--no-fallback"]
	//> using scala "3.8.2"
	//> using jvm "graalvm-java25:25.0.1"
	//> using packaging.packageType "graalvm"
	//> using packaging.output "echo"
	//> using packaging.graalvmArgs "--no-fallback"

	object Echo:
	def main(args: Array[String]): Unit =
	println(args.mkString(" "))
	#!/usr/bin/env sh

	set -e

	if [ -z "${DEFAULT_MILL_VERSION}" ] ; then DEFAULT_MILL_VERSION="1.1.3"; fi

	if [ -z "${GITHUB_RELEASE_CDN}" ] ; then GITHUB_RELEASE_CDN=""; fi

	if [ -z "$MILL_MAIN_CLI" ] ; then MILL_MAIN_CLI="${0}"; fi

	MILL_REPO_URL="https://github.com/com-lihaoyi/mill"

	MILL_BUILD_SCRIPT=""

	if [ -f "build.mill" ] ; then
	MILL_BUILD_SCRIPT="build.mill"
	elif [ -f "build.mill.scala" ] ; then
	MILL_BUILD_SCRIPT="build.mill.scala"
	elif [ -f "build.sc" ] ; then
	MILL_BUILD_SCRIPT="build.sc"
	fi

	# `s/.*://`:
	# This is a greedy match that removes everything from the beginning of the line up to (and including) the last
	# colon (:). This effectively isolates the value part of the declaration.
	#
	# `s/#.*//`:
	# This removes any comments at the end of the line.
	#
	# `s/['\"]//g`:
	# This removes all single and double quotes from the string, wherever they appear (g is for "global").
	#
	# `s/^[[:space:]]//; s/[[:space:]]$//`:
	# These two expressions trim any leading or trailing whitespace ([[:space:]] matches spaces and tabs).
	TRIM_VALUE_SED="s/.://; s/#.//; s/['\"]//g; s/^[[:space:]]//; s/[[:space:]]$//"

	if [ -z "${MILL_VERSION}" ] ; then
	if [ -f ".mill-version" ] ; then
	MILL_VERSION="$(tr '\r' '\n' < .mill-version \| head -n 1 2> /dev/null)"
	elif [ -f ".config/mill-version" ] ; then
	MILL_VERSION="$(tr '\r' '\n' < .config/mill-version \| head -n 1 2> /dev/null)"
	elif [ -f "build.mill.yaml" ] ; then
	MILL_VERSION="$(grep -E "mill-version:" "build.mill.yaml" \| sed -E "$TRIM_VALUE_SED")"
	elif [ -n "${MILL_BUILD_SCRIPT}" ] ; then
	MILL_VERSION="$(grep -E "//\\|.*mill-version" "${MILL_BUILD_SCRIPT}" \| sed -E "$TRIM_VALUE_SED")"
	fi
	fi

	if [ -z "${MILL_VERSION}" ] ; then MILL_VERSION="${DEFAULT_MILL_VERSION}"; fi

	MILL_USER_CACHE_DIR="${XDG_CACHE_HOME:-${HOME}/.cache}/mill"

	if [ -z "${MILL_FINAL_DOWNLOAD_FOLDER}" ] ; then MILL_FINAL_DOWNLOAD_FOLDER="${MILL_USER_CACHE_DIR}/download"; fi

	MILL_NATIVE_SUFFIX="-native"
	MILL_JVM_SUFFIX="-jvm"
	ARTIFACT_SUFFIX=""

	# Check if GLIBC version is at least the required version
	# Returns 0 (true) if GLIBC >= required version, 1 (false) otherwise
	check_glibc_version() {
	required_version="2.39"
	required_major=$(echo "$required_version" \| cut -d. -f1)
	required_minor=$(echo "$required_version" \| cut -d. -f2)
	# Get GLIBC version from ldd --version (first line contains version like "ldd (GNU libc) 2.31")
	glibc_version=$(ldd --version 2>/dev/null \| head -n 1 \| grep -oE '[0-9]+\.[0-9]+$' \|\| echo "")
	if [ -z "$glibc_version" ]; then
	# If we can't determine GLIBC version, assume it's too old
	return 1
	fi
	glibc_major=$(echo "$glibc_version" \| cut -d. -f1)
	glibc_minor=$(echo "$glibc_version" \| cut -d. -f2)
	if [ "$glibc_major" -gt "$required_major" ]; then
	return 0
	elif [ "$glibc_major" -eq "$required_major" ] && [ "$glibc_minor" -ge "$required_minor" ]; then
	return 0
	else
	return 1
	fi
	}

	set_artifact_suffix() {
	if [ "$(uname -s 2>/dev/null \| cut -c 1-5)" = "Linux" ]; then
	# Native binaries require new enough GLIBC; fall back to JVM launcher if older
	if ! check_glibc_version; then
	return
	fi
	if [ "$(uname -m)" = "aarch64" ]; then ARTIFACT_SUFFIX="-native-linux-aarch64"
	else ARTIFACT_SUFFIX="-native-linux-amd64"; fi
	elif [ "$(uname)" = "Darwin" ]; then
	if [ "$(uname -m)" = "arm64" ]; then ARTIFACT_SUFFIX="-native-mac-aarch64"
	else ARTIFACT_SUFFIX="-native-mac-amd64"; fi
	else
	echo "This native mill launcher supports only Linux and macOS." 1>&2
	exit 1
	fi
	}

	case "$MILL_VERSION" in
	*"$MILL_NATIVE_SUFFIX")
	MILL_VERSION=${MILL_VERSION%"$MILL_NATIVE_SUFFIX"}
	set_artifact_suffix
	;;

	*"$MILL_JVM_SUFFIX")
	MILL_VERSION=${MILL_VERSION%"$MILL_JVM_SUFFIX"}
	;;

	*)
	case "$MILL_VERSION" in
	0.1.* \| 0.2.* \| 0.3.* \| 0.4.* \| 0.5.* \| 0.6.* \| 0.7.* \| 0.8.* \| 0.9.* \| 0.10.* \| 0.11.* \| 0.12.*)
	;;
	*)
	set_artifact_suffix
	;;
	esac
	;;
	esac

	MILL="${MILL_FINAL_DOWNLOAD_FOLDER}/$MILL_VERSION$ARTIFACT_SUFFIX"

	# If not already downloaded, download it
	if [ ! -s "${MILL}" ] \|\| [ "$MILL_TEST_DRY_RUN_LAUNCHER_SCRIPT" = "1" ] ; then
	case $MILL_VERSION in
	0.0.* \| 0.1.* \| 0.2.* \| 0.3.* \| 0.4.*)
	MILL_DOWNLOAD_SUFFIX=""
	MILL_DOWNLOAD_FROM_MAVEN=0
	;;
	0.5.* \| 0.6.* \| 0.7.* \| 0.8.* \| 0.9.* \| 0.10.* \| 0.11.0-M*)
	MILL_DOWNLOAD_SUFFIX="-assembly"
	MILL_DOWNLOAD_FROM_MAVEN=0
	;;
	*)
	MILL_DOWNLOAD_SUFFIX="-assembly"
	MILL_DOWNLOAD_FROM_MAVEN=1
	;;
	esac
	case $MILL_VERSION in
	0.12.0 \| 0.12.1 \| 0.12.2 \| 0.12.3 \| 0.12.4 \| 0.12.5 \| 0.12.6 \| 0.12.7 \| 0.12.8 \| 0.12.9 \| 0.12.10 \| 0.12.11)
	MILL_DOWNLOAD_EXT="jar"
	;;
	0.12.*)
	MILL_DOWNLOAD_EXT="exe"
	;;
	0.*)
	MILL_DOWNLOAD_EXT="jar"
	;;
	*)
	MILL_DOWNLOAD_EXT="exe"
	;;
	esac

	MILL_TEMP_DOWNLOAD_FILE="${MILL_OUTPUT_DIR:-out}/mill-temp-download"
	mkdir -p "$(dirname "${MILL_TEMP_DOWNLOAD_FILE}")"

	if [ "$MILL_DOWNLOAD_FROM_MAVEN" = "1" ] ; then
	MILL_DOWNLOAD_URL="https://repo1.maven.org/maven2/com/lihaoyi/mill-dist${ARTIFACT_SUFFIX}/${MILL_VERSION}/mill-dist${ARTIFACT_SUFFIX}-${MILL_VERSION}.${MILL_DOWNLOAD_EXT}"
	else
	MILL_VERSION_TAG=$(echo "$MILL_VERSION" \| sed -E 's/([^-]+)(-M[0-9]+)?(-.*)?/\1\2/')
	MILL_DOWNLOAD_URL="${GITHUB_RELEASE_CDN}${MILL_REPO_URL}/releases/download/${MILL_VERSION_TAG}/${MILL_VERSION}${MILL_DOWNLOAD_SUFFIX}"
	unset MILL_VERSION_TAG
	fi


	if [ "$MILL_TEST_DRY_RUN_LAUNCHER_SCRIPT" = "1" ] ; then
	echo "$MILL_DOWNLOAD_URL"
	echo "$MILL"
	exit 0
	fi

	echo "Downloading mill ${MILL_VERSION} from ${MILL_DOWNLOAD_URL} ..." 1>&2
	curl -f -L -o "${MILL_TEMP_DOWNLOAD_FILE}" "${MILL_DOWNLOAD_URL}"

	chmod +x "${MILL_TEMP_DOWNLOAD_FILE}"

	mkdir -p "${MILL_FINAL_DOWNLOAD_FOLDER}"
	mv "${MILL_TEMP_DOWNLOAD_FILE}" "${MILL}"

	unset MILL_TEMP_DOWNLOAD_FILE
	unset MILL_DOWNLOAD_SUFFIX
	fi

	MILL_FIRST_ARG=""
	if [ "$1" = "--bsp" ] \|\| [ "${1#"-i"}" != "$1" ] \|\| [ "$1" = "--interactive" ] \|\| [ "$1" = "--no-server" ] \|\| [ "$1" = "--no-daemon" ] \|\| [ "$1" = "--help" ] ; then
	# Need to preserve the first position of those listed options
	MILL_FIRST_ARG=$1
	shift
	fi

	unset MILL_FINAL_DOWNLOAD_FOLDER
	unset MILL_OLD_DOWNLOAD_PATH
	unset OLD_MILL
	unset MILL_VERSION
	unset MILL_REPO_URL

	# -D mill.main.cli is for compatibility with Mill 0.10.9 - 0.13.0-M2
	# 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}" "$@"