This repository gathers Scala 3 code examples coming from various websites - mostly from the Dotty project - or written by ourself. In particular it includes build scripts (Ant files, Bash scripts, batch files, Gradle scripts, Make scripts, Maven scripts) for experimenting with the Scala 3 language on a Windows machine.

This document is part of a series of topics related to Scala 3 on Windows:

• Running Scala 3 on Windows ▼
• Building Scala 3 on Windows
• Data Sharing and Scala 3 on Windows
• OpenJDK and Scala 3 on Windows

Ada, Akka, C++, COBOL, Dafny, Dart, Deno, Docker, Erlang, Flix, Golang, GraalVM, Haskell, Kafka, Kotlin, LLVM, Modula-2, Node.js, Rust, Spark, Spring, TruffleSqueak, WiX Toolset and Zig are other topics we are continuously monitoring.

This project depends on the following external software for the Microsoft Windows platform:

• Git 2.47 (release notes)
• Scala 3.3 LTS ¹ (release notes)
• Temurin OpenJDK 17 LTS ² (release notes, bug fixes, Java 17 API)

Optionally one may also install the following software:

• Apache Ant 1.10 (requires Java 8) (release notes)
• Apache Maven 3.9 (requires Java 8+) (release notes)
• Bazel 7.4 LTS ³ (release notes)
• CFR 0.15 (Java decompiler)
• Gradle 8.10 (requires Java 8+) (release notes)
• JaCoCo 0.8 ⁴ (change log)
• JavaFX 17 LTS (release notes)
• JavaFX 21 LTS (release notes)
• JITWatch 1.4 (requires Java 11+)
• Mill 0.12 (change log)
• MSYS2 2024 (change log)
• sbt 1.10 (requires Java 8+) (release notes)
• Scala 2.13 (requires Java 8+) (release notes, Scala API)
• Scala 2.13 DEV
• Scala 3.5 Next ⁵ (release notes)
• scala-cli 1.5 (release notes)
• Temurin OpenJDK 21 LTS ² (release notes, Java 21 API)
• Visual Studio Code 1.95 (release notes)

☛ Installation policy
When possible we install software from a Zip archive rather than via a Windows installer. In our case we defined C:\opt\ as the installation directory for optional software tools (in reference to the /opt/ directory on Unix).

For instance our development environment looks as follows (November 2024) ⁶:

C:\opt\apache-ant\                 ( 40 MB)
C:\opt\apache-maven\               ( 10 MB)
C:\opt\bazel\                      ( 47 MB)
C:\opt\cfr-0.152\                  (  2 MB)
C:\opt\Git\                        (367 MB)
C:\opt\gradle\                     (138 MB)
C:\opt\jacoco\                     ( 10 MB)
C:\opt\javafx-sdk-17.0.13\         (137 MB)
C:\opt\javafx-sdk-21.0.5\          (138 MB)
C:\opt\jdk-temurin-1.8.0u422-b05\  (189 MB)
C:\opt\jdk-temurin-17.0.13_11\     (301 MB)
C:\opt\jdk-temurin-21.0.5_11\      (326 MB)
C:\opt\jitwatch-1.4.9\             ( 36 MB)
C:\opt\mill\                       ( 67 MB)
C:\opt\msys64\                     (5.5 GB)
C:\opt\Python-3.11.1\              (299 MB)
C:\opt\sbt\                        (110 MB)
C:\opt\scala-2.13.15\              ( 24 MB)
C:\opt\scala-cli\                  ( 95 MB)
C:\opt\scala3-3.3.4\               ( 38 MB)
C:\opt\scala3-3.5.2\               (131 MB)
C:\opt\VSCode\                     (341 MB)

🔎 Git for Windows provides a Bash emulation used to run git.exe from the command line (as well as over 250 Unix commands like awk, diff, file, grep, more, mv, rmdir, sed and wc).

This project is organized as follows:

bin\*.bat
bin\cfr-0.152.zip
bin\3.0\{common.bat, scala.bat, scalac.bat, scaladoc.bat}
bin\3.1\{common.bat, scala.bat, scalac.bat, scaladoc.bat}
bin\3.2\{common.bat, scala.bat, scalac.bat, scaladoc.bat}
bin\dotty\
docs\
dotty\     (Git submodule)
examples\{README.md, dotty-example-project, ..}
maven-plugins\{README.md, scala-maven-plugin, etc.}
myexamples\{README.md, 00_AutoParamTupling, ..}
plugin-examples\{README.md, DivideZero, ..}
rockthejvm-examples\{README.md, Enums, ..}
semanticdb-examples\{README.md, hello, ..}
CONTRIBUTIONS.md
DEPS.md
README.md
RESOURCES.md
setenv.bat
UBUNTU_WSL.md

where

• directory bin\ provides several utility batch files.
• file bin\cfr-0.152.zip contains a zipped distribution of CFR.
• directory bin\3.2\ contains the batch commands for Scala 3.
• directory bin\dotty\ contains several batch files/bash scripts for building the Scala 3 software distribution on a Windows machine.
• directory docs\ contains Scala 3 related papers/articles (see file docs\README.md).
• directory dotty\ contains our fork of the lampepfl/dotty repository as a Github submodule.
• directory examples\ contains Scala 3 examples grabbed from various websites (see file examples\README.md).
• directory maven-plugins\ presents our Maven plugin scala-maven-plugin.
• directory myexamples\ contains self-written Scala 3 examples (see file myexamples\README.md).
• directory plugin-examples\ contains Scala 3 plugin examples (see file plugin-examples\README.md).
• directory rockthejvm-examples\ contains Scala 3 code examples (see file rockthejvm-examples\README.md).
• directory semanticdb-examples\ contains SemanticDB code examples (see file semanticdb-examples\README.md).
• file CONTRIBUTIONS.md lists PRs and issues we reported so far.
• file DEPS.md lists library dependencies of available Scala distributions.
• file README.md is the Markdown document for this page.
• file RESOURCES.md is the Markdown document presenting external resources.
• file setenv.bat is the batch command for setting up our environment.
• file UBUNTU_WSL.md presents a Scala 3 code examples in Ubuntu WSL.

We also define a virtual drive – e.g. drive Y: – in our working environment in order to reduce/hide the real path of our project directory (see article "Windows command prompt limitation" from Microsoft Support).

🔎 Inside batch file setenv.bat we use the Windows external command subst to create virtual drives; for instance:

> subst Y: %USERPROFILE%\workspace\dotty-examples

In the next section we give a brief description of the batch files present in this project.

We distinguish different sets of batch/bash commands:

1. setenv.bat – This batch command makes external tools such as maven.cmd, mill.bat and sbt.bat directly available from the command prompt (see section Project dependencies).

   > setenv help
   Usage: setenv { <option> | <subcommand> }
    
     Options:
       -bash       start Git bash shell instead of Windows command prompt
       -debug      print commands executed by this script
       -verbose    print progress messages
    
     Subcommands:
       help        print this help message
   

2. Directory bin\ – This directory contains several utility batch files:

   • cleanup.bat removes the generated class files from every example directory (both in examples\ and myexamples\ directories).
   • dirsize.bat <dir_path_1> .. prints the size in Kb/Mb/Gb of the specified directory paths.
   • getnightly.bat downloads/installs the distribution from the latest Dotty nightly build.
   • searchjars.bat <class_name> searches for the given class name into all Scala JAR files.
   • timeit.bat <cmd_1> { & <cmd_2> } prints the execution time of the specified commands.
   • touch.bat <file_path> updates the modification date of an existing file or creates a new one.
      

3. Directory bin\3.0\ - This directory contains batch files to be copied to the bin\ directory of the Scala 3 installation for versions prior to 3.0.2 in order to use the scalac.bat, scaladoc.bat and scala.bat commands on Microsoft Windows.

   ☛ Starting with version 3.0.2 those batch files are included in the Scala 3 software distribution (see PR#13006, itself based on PR#5444).

    > dir /b c:\opt\scala3-3.3.4\bin
    common
    common.bat
    scala
    scala.bat
    scalac
    scalac.bat
    scaladoc
    scaladoc.bat
    

4. File bin\dotty\build.bat - This batch command generates the Scala 3 software distribution from the Windows command prompt.

5. File bin\dotty\build.sh - This bash command generates the Scala 3 software distribution from the Git Bash command prompt.

6. File examples\*\build.bat - Finally each example can be built/run using the build.bat command.
   

   ☛ We favor build.bat for the following reasons:

   • It matches user commands executed from the Windows command prompt.
   • It provides subcommands for working with CFR, Scalafmt, JUnit and more.
   • Code examples are simple (mostly one single source file).
   • We don't need the sbt machinery (eg. library dependencies, sbt server).

    > build
    Usage: build { <option> | <subcommand> }
     
      Options:
        -debug           print commands executed by this script
        -explain         set compiler option -explain
        -explain-types   set compiler option -explain-types
        -main:<name>     define main class name (default: Main)
        -print           print IR after compilation phase 'lambdaLift'
        -scala2          use Scala 2 tools
        -scala3          use Scala 3 tools (default)
        -tasty           compile both from source and TASTy files
        -timer           print the execution time
        -verbose         print progress messages
     
      Subcommands:
        clean            delete generated files
        compile          compile Java/Scala source files
        decompile        decompile generated code with CFR
        doc              generate HTML documentation
        help             print this help message
        lint             analyze Scala source files with Scalafmt
        run[:i]          execute main class (instrumented execution: :i)
        test             execute unit tests with JUnit
     
      Properties:
      (to be defined in SBT configuration file project\build.properties)
        main.class       alternative to option -main:<name>
        main.args        list of arguments to be passed to main class
    

1. Build tools

   Code examples in directories examples\ and myexamples\ can also be built with the following tools as an alternative to the build.bat command (see examples\README.md and myexamples\README.md for more details):

   Build tool	Build file	Parent file	Usage example
   ant.bat	build.xml	build.xml	antclean compile run
   bazel.exe	BUILD	n.a.	bazelrun :enum-Planet
   cmd.exe	build.bat		build clean run
   gradle.bat	build.gradle	common.gradle	gradleclean build run
   make.exe	Makefile	Makefile.inc	makeclean run
   mill.bat	build.sc	common.sc	mill -i app
   mvn.cmd	pom.xml	pom.xml	mvnclean compile test
   sbt.bat	build.sbt	n.a.	sbtclean compile run

2. Decompiler tools

   As an alternative to the standard javap.exe class decompiler one may use cfr.bat (simply extract bin\cfr-0.152.zip to c:\opt\) which prints Java source code instead of Java bytecode:

    > cfr myexamples\00_AutoParamTupling\target\classes\myexamples\Main.class
    /*
     * Decompiled with CFR 0.152.
     */
    package myexamples;
    
    import myexamples.Main$;
    
    public final class Main {
        public static void test01() {
            Main$.MODULE$.test01();
        }
    
        public static void main(String[] arrstring) {
            Main$.MODULE$.main(arrstring);
        }
    
        public static void test02() {
            Main$.MODULE$.test02();
        }
    }
    

   Here is the console output from command javap.exe with option -c for the same class file:

    > javap -c myexamples\00_AutoParamTupling\target\classes\myexamples\Main.class
    Compiled from "Main.scala"
    public final class myexamples.Main {
      public static void main(java.lang.String[]);
        Code:
           0: getstatic     #13                 // Field myexamples/Main$.MODULE$:Lmyexamples/Main$;
           3: aload_0
           4: invokevirtual #15                 // Method myexamples/Main$.main:([Ljava/lang/String;)V
           7: return
    
      public static void test02();
        Code:
           0: getstatic     #13                 // Field myexamples/Main$.MODULE$:Lmyexamples/Main$;
           3: invokevirtual #19                 // Method myexamples/Main$.test02:()V
           6: return
    
      public static void test01();
        Code:
           0: getstatic     #13                 // Field myexamples/Main$.MODULE$:Lmyexamples/Main$;
           3: invokevirtual #22                 // Method myexamples/Main$.test01:()V
           6: return
    }
    

We execute command setenv.bat once to setup our development environment; it makes external tools such as bazel.exe, mvn.cmd, sbt.bat and git.exe directly available from the command prompt.

> setenv
Tool versions:
   javac 17.0.13, scalac 2.13.15, scalac 3.3.4, scalafmt 3.7.17,
   ant 1.10.15, gradle 8.10.2, mvn 3.9.9, sbt 1.10.3, scala-cli 1.5.1,
   mill 0.12.1, bazel 7.4.0, cfr 0.152, make 3.81, python 3.11.1,
   jacoco 0.8.12, git 2.47.0, diff 3.10, bash 5.2.37(1)

> where sbt scala-cli
C:\opt\sbt\bin\sbt
C:\opt\sbt\bin\sbt.bat
C:\opt\scala-cli\scala-cli.exe

Other development tools such as javac.exe and scalac.bat are accessible through the corresponding environment variable, e.g. JAVA_HOME for javac.exe, SCALA_HOME resp. SCALA3_HOME for scalac.bat and PYTHON_HOME for python.exe.

> where javac
INFO: Could not find files for the given pattern(s).
 
> where /r %JAVA_HOME% javac
C:\opt\jdk-temurin-17.0.13_11\bin\javac.exe
 
> %JAVA_HOME%\bin\javac -version
javac 17.0.13

Command setenv.bat -verbose also prints the tool paths and defined environment variables:

> setenv -verbose
Tool versions:
   javac 17.0.13, scalac 2.13.15, scalac 3.3.4, scalafmt 3.7.12,
   ant 1.10.15, gradle 10, mvn 3.9.9, sbt 1.10.3, scala-cli 1.5.1,
   mill 0.12.1, bazel 7.4.0, cfr 0.152, make 3.81, python 3.11.1,
   jacoco 0.8.12, git 2.47.0, diff 3.10, bash 5.2.37(1)
Tool paths:
   C:\opt\jdk-temurin-11.0.21_9\bin\javac.exe
   C:\opt\scala-2.13.15\bin\scalac.bat
   C:\opt\scala3-3.3.4\bin\scalac.bat
   %LOCALAPPDATA%\Coursier\data\bin\scalafmt.bat
   C:\opt\apache-ant\bin\ant.bat
   C:\opt\gradle\bin\gradle.bat
   C:\opt\mill\mill.bat
   C:\opt\apache-maven\bin\mvn.cmd
   C:\opt\sbt\bin\sbt.bat
   C:\opt\scala-cli\scala-cli.exe
   C:\opt\mill\mill.bat
   C:\opt\bazel\bazel.exe
   C:\opt\cfr-0.152\bin\cfr.bat
   C:\opt\make-3.81\bin\make.exe
   C:\opt\Python-3.11.1\python.exe
   C:\opt\jacoco\lib\jacococli.jar
   C:\opt\Git\bin\git.exe
   C:\opt\Git\usr\bin\diff.exe
   C:\opt\Git\bin\bash.exe
Environment variables:
   "ANT_HOME=C:\opt\apache-ant"
   "BAZEL_HOME=c:\opt\bazel"
   "CFR_HOME=C:\opt\cfr-0.152"
   "COURSIER_DATA_DIR=%LOCALAPPDATA%\coursier\data"
   "COURSIER_HOME=C:\opt\coursier-2.1.7"
   "GIT_HOME=C:\opt\Git"
   "GRADLE_HOME=C:\opt\gradle"
   "JAVA_HOME=C:\opt\jdk-temurin-17.0.13_11"
   "JAVA17_HOME=C:\opt\jdk-temurin-17.0.13_11"
   "JAVA21_HOME=C:\opt\jdk-temurin-21.0.5_11"
   "JAVAFX_HOME=C:\opt\javafx-sdk-21.0.5"
   "MSVS_HOME=X:"
   "MSYS_HOME=C:\opt\msys64"
   "PYTHON_HOME=C:\opt\Python-3.11.1"
   "SBT_HOME=C:\opt\sbt"
   "SCALA_CLI_HOME=C:\opt\scala-cli"
   "SCALA_HOME=C:\opt\scala-2.13.15"
   "SCALA3_HOME=C:\opt\scala3-3.3.4"
   "SCALA3_NEXT_HOME=C:\opt\scala3-3.5.2"
Path associations:
   I:\: => %USERPROFILE%\workspace-perso\dotty-examples

Command cleanup.bat removes the output directories (ie. target\) from the example projects:

> cleanup
Finished to clean up 2 subdirectories in Y:\dotty\cdsexamples
Finished to clean up 16 subdirectories in Y:\dotty\examples
Finished to clean up 12 subdirectories in Y:\dotty\myexamples

Command dirsize.bat returns the size (in Kb, Mb or Gb) of the specified directory paths:

> dirsize examples myexamples c:\opt\scala3-3.3.4 c:\opt\jdk-temurin-17.0.13_11
Size of directory "examples" is 3.9 Mb
Size of directory "myexamples" is 1.2 Mb
Size of directory "c:\opt\scala3-3.3.4" is 35.7 Mb
Size of directory "c:\opt\jdk-temurin-17.0.13_11" is 304.0 Mb

By default command getnightly.bat downloads the library files of the latest Dotty nightly build available from the Maven Central Repository and saves them into directory out\nightly\.

> getnightly
Usage: getnightly { <option> | <subcommand> }
 
  Options:
    -debug      print commands executed by this script
    -timer      print total execution time
    -verbose    print download progress
 
  Subcommands:
    activate    activate the nightly build library files
    download    download nighty build files and quit (default)
    help        print this help message
    restore     restore the default Scala library files

Command getnightly.bat download with options -verbose also displays the download progress:

> getnightly -verbose download
Delete directory "out\nightly"
Download Scala 3 nightly files from Maven repository
Downloading file scala3-language-server_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 148.9 Kb
Downloading file scala3-compiler_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 20.3 Mb
Downloading file scala3-sbt-bridge-3.5.0-RC1-bin-20240514-7c9aae3-NIGHTLY.jar ... 31.2 Kb
Downloading file scala3-tasty-inspector_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 17.4 Kb
Downloading file scala3-library_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 1.2 Mb
Downloading file scala2-library-tasty-experimental_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 3 Mb
Downloading file scala3-staging_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 40.7 Kb
Downloading file scala3-presentation-compiler_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 1.7 Mb
Downloading file scala3-library_sjs1_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 1.9 Mb
Downloading file scala3-interfaces-3.5.0-RC1-bin-20240514-7c9aae3-NIGHTLY.jar ... 3.9 Kb
Downloading file scala2-library-cc-tasty-experimental_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 3 Mb
Downloading file scaladoc_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 4.7 Mb
Downloading file tasty-core_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar ... 94.5 Kb
Downloading file antlr4-runtime-4.7.2.jar ... 330 Kb
[...]
Downloading file common ... 6 Kb
Downloading file common.bat ... 2.9 Kb
Converting file common.bat to DOS format
Downloading file scala ... 1.8 Kb
Downloading file scala.bat ... 2.6 Kb
Converting file scala.bat to DOS format
Downloading file scalac ... 2.5 Kb
Downloading file scalac.bat ... 3.7 Kb
Converting file scalac.bat to DOS format
Downloading file scaladoc ... 5 Kb
Downloading file scaladoc.bat ... 4.6 Kb
Converting file scaladoc.bat to DOS format
Finished to download 54 files to directory "%LOCALAPPDATA%\Temp\scala3-nightly"
Retrieve revision for hash "3e105f2" from GitHub repository "lampepfl/dotty"
File "%LOCALAPPDATA%\Temp\scala3-nightly\VERSION":
version:=3.6.2-RC1-bin-20240514-7c9aae3-NIGHTLY
revision:=7c9aae3
buildTime:=2024-05-15 23:09:19+02:00

Output directory %TEMP%\scala3-nightly\ contains the two subdirectories bin\ and lib\:

> dir /b %TEMP%\scala3-nightly\bin %TEMP%\scala3-nightly\lib
common
common.bat
scala
scala.bat
scalac
scalac.bat
scaladoc
scaladoc.bat
antlr-runtime-4.7.2.jar
autolink-0.6.0.jar
[...]
scala-asm-9.6.0-scala-1.jar
scala-library-2.13.12.jar
scala2-library-cc-tasty-experimental_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala2-library-tasty-experimental_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala3-compiler_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala3-interfaces-3.5.0-RC1-bin-20240514-7c9aae3-NIGHTLY.jar
scala3-language-server_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala3-library_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala3-library_sjs1_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala3-presentation-compiler_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala3-sbt-bridge-3.6.2-RC1-bin-20240514-7c9aae3-NIGHTLY.jar
scala3-staging_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scala3-tasty-inspector_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
scaladoc_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar
snakeyaml-2.0.jar
strftime4j-1.0.6.jar
tasty-core_3.6.2-RC1-bin-20241025-91ef921-NIGHTLY.jar

Concretely, subcommand activate switches to the nightly build version and subcommand restore restore the path to the Scala 3 installation directory.

> getnightly activate
Active Scala 3 installation is 3.6.2-RC1-bin-20241025-91ef921-NIGHTLY (was 3.3.4)

> %SCALA3_HOME%\bin\scalac -version
Scala compiler version 3.6.2-RC1 -- Copyright 2002-2024, LAMP/EPFL

> getnightly restore
Active Scala 3 installation is 3.3.4

> %SCALA3_HOME%\bin\scalac -version
Scala compiler version 3.3.4 -- Copyright 2002-2024, LAMP/EPFL

⚠️ You need write access to the Scala 3 installation directory (e.g. C:\opt\scala3-3.3.4\ in our case) in order to successfully run the activate/reset subcommands.

Command searchjars.bat helps us to search for class file names in the following directories: project's lib\ directory (if present), Scala's lib\ directory, Java's lib\ directory and Ivy/Maven default local directories.

> searchjars -help
Usage: searchjars { <option> | <class_name> }
 
  Options:
    -artifact        search in ~\.ivy2 and ~\.m2 directories
    -help            print this help message
    -ivy             search in ~\.ivy directory
    -java            search in Java library directories
    -maven           search in ~\.m2 directory
    -scala           search in Scala library directories
    -verbose         print progress messages
 
  Arguments:
    <class_name>     class name

For instance we get the following output when passing class name System to command searchjars.bat (class file names are printed with full path and are prefixed with their containing JAR file):

> searchjars System
Searching for class name System in archive files C:\opt\scala3-3.3.4\lib\*.jar
  jline-reader-3.19.0.jar:org/jline/reader/impl/completer/SystemCompleter.class
  scala-library-2.13.15.jar:scala/sys/SystemProperties$.class
  scala-library-2.13.15.jar:scala/sys/SystemProperties.class
Searching for class name System in archive files C:\opt\scala-2.13.15\lib\*.jar
  jline-3.19.0.jar:org/jline/builtins/SystemRegistryImpl$CommandOutputStream.class
  [...]
  scala-library.jar:scala/sys/SystemProperties$.class
  scala-library.jar:scala/sys/SystemProperties.class
Searching for class name System in archive files C:\opt\jdk-temurin-17.0.13_11\lib\*.jar
  jrt-fs.jar:jdk/internal/jrtfs/JrtFileSystem$1.class
  [...]
  jrt-fs.jar:jdk/internal/jrtfs/SystemImage$2.class
  jrt-fs.jar:jdk/internal/jrtfs/SystemImage.class
Searching for class name System in archive files c:\opt\javafx-sdk-17.0.13_11\lib\*.jar
  javafx.graphics.jar:com/sun/glass/ui/SystemClipboard.class
  [...]
  javafx.graphics.jar:com/sun/javafx/tk/TKSystemMenu.class
  javafx.web.jar:com/sun/webkit/FileSystem.class

Searching for an unknown class name - e.g. BinarySearch - produces the following output:

> searchjars BinarySearch
Searching for class name BinarySearch in archive files C:\opt\scala3-3.3.4\lib\*.jar
Searching for class name BinarySearch in archive files C:\opt\scala-2.13.15\lib\*.jar
Searching for class name BinarySearch in archive files C:\opt\jdk-temurin-17.0.13_11\lib\*.jar

Searching for FileSystem with option -artifact produces the following output:

> searchjars FileSystem -artifact
Searching for class name FileSystem in archive files C:\opt\scala3-3.3.4\lib\*.jar
Searching for class name FileSystem in archive files C:\opt\scala-2.13.15\lib\*.jar
Searching for class name FileSystem in archive files c:\opt\jdk-temurin-17.0.13_11\lib\*.jar
  jrt-fs.jar:jdk/internal/jrtfs/JrtFileSystem$1.class
  jrt-fs.jar:jdk/internal/jrtfs/JrtFileSystem.class
  jrt-fs.jar:jdk/internal/jrtfs/JrtFileSystemProvider$1.class
  jrt-fs.jar:jdk/internal/jrtfs/JrtFileSystemProvider$JrtFsLoader.class
  jrt-fs.jar:jdk/internal/jrtfs/JrtFileSystemProvider.class
Searching for class name FileSystem in archive files c:\opt\javafx-sdk-17\lib\*.jar
  javafx.web.jar:com/sun/webkit/FileSystem.class
Searching for class name FileSystem in archive files %USERPROFILE%\.ivy2\cache\*.jar
  okhttp-3.14.2.jar:okhttp3/internal/io/FileSystem$1.class
  okhttp-3.14.2.jar:okhttp3/internal/io/FileSystem.class
  ivy-2.3.0-sbt-839fad1cdc07cf6fc81364d74c323867230432ad.jar:org/apache/ivy/plugins/resolver/FileSystemResolver.class
  ivy-2.3.0-sbt-88d6a93d15f9b029958c1c289a8859e8dfe31a19.jar:org/apache/ivy/plugins/resolver/FileSystemResolver.class
  ivy-2.3.0-sbt-fa726854dd30be842ff9e6d2093df6adfe3871f5.jar:org/apache/ivy/plugins/resolver/FileSystemResolver.class
Searching for class name FileSystem in archive files %USERPROFILE%\.m2\repository\*.jar
  commons-io-2.2.jar:org/apache/commons/io/FileSystemUtils.class
  commons-io-2.5.jar:org/apache/commons/io/FileSystemUtils.class
  commons-io-2.6.jar:org/apache/commons/io/FileSystemUtils.class
  ivy-2.4.0.jar:org/apache/ivy/plugins/resolver/FileSystemResolver.class
  sigar-1.6.4.jar:org/hyperic/sigar/FileSystem.class
  [...]
  stagemonitor-os-0.88.9.jar:org/stagemonitor/os/metrics/FileSystemMetricSet.class

Batch file timeit.bat prints the execution time (hh:MM:ss format) of the specified command (possibly given with options and parameters):

> timeit dir /b
.gitignore
.gradle
build.bat
build.gradle
build.sbt
build.sc
build.xml
pom.xml
project
settings.gradle
src
target
Execution time: 00:00:01
 
> timeit build clean compile
Execution time: 00:00:08

Chaining of commands is also possible. Note that the command separator (either && or &) must be escaped if the command chain is not quoted. For instance:

s
> timeit build clean compile ^&^& ant run
...
Execution time: 00:00:11
> timeit "build clean compile && ant run"
...
Execution time: 00:00:11

🔎 The && command separator performs error checking - that is, the commands to the right of the && command run if and only if the command to the left of && succeeds. The & command does not perform error checking - that is, all commands run.

Batch file build.bat is a basic build script consisting of ~800 lines of batch/Powershell code ⁷.

Running command build.bat with no option in project examples\enum-Planet generates the following output:

> build clean compile run
Your weight on MERCURY (0) is 0.37775761520093526
Your weight on SATURN (5) is 1.0660155388115666
Your weight on VENUS (1) is 0.9049990998410455
Your weight on URANUS (6) is 0.9051271993894251
Your weight on EARTH (2) is 0.9999999999999999
Your weight on NEPTUNE (7) is 1.1383280724696578
Your weight on MARS (3) is 0.37873718403712886
Your weight on JUPITER (4) is 2.5305575254957406

More usage examples are presented in examples\README.md resp. myexamples\README.md

Scala REPL is an interactive tool for evaluating Scala expressions. Internally, it executes a source script by wrapping it in a template and then compiling and executing the resulting program.

⚠️ Batch file scala.bat is based on the bash script scala available from the standard Scala 3 distribution. We also have submitted pull request #5444 to add that batch file to the Scala 3 distribution.

> where scala
C:\opt\scala3-3.3.4\bin\scala
C:\opt\scala3-3.3.4\bin\scala.bat

> scala -version
Scala code runner version 3.3.4 -- Copyright 2002-2024, LAMP/EPFL

> scala
Starting scala REPL...
scala> :help
The REPL has several commands available:

:help                    print this summary
:load <path>             interpret lines in a file
:quit                    exit the interpreter
:type <expression>       evaluate the type of the given expression
:imports                 show import history
:reset                   reset the repl to its initial state, forgetting all session entries

scala> System.getenv().get("JAVA_HOME")
val res0: String = C:\opt\jdk-temurin-17.0.13_11

scala> System.getenv().get("SCALA3_HOME")
val res1: String = C:\opt\scala3-3.3.4

scala> :load myexamples/HelloWorld/src/main/scala/HelloWorld.scala
// defined object HelloWorld

scala> HelloWorld.main(Array())
Hello world!

scala>:quit

[1] Scala 3 LTS versions ↩

The distinction between LTS and Next versions of Scala 3 is presented on the page "Long-term compatibility plans for Scala 3" posted on August 17, 2022.

In particular it makes the following statement : "We suggest end users stick to the LTS version. It will give you the best tooling support and a stable compiler. If you are migrating a bigger project from Scala 2, you should migrate it straight to the newest LTS."

[2] Java LTS versions ↩

Oracle annonces in his Java SE Support Roadmap he will stop public updates of Java SE 8 for commercial use after January 2019. Current LTS versions are (from Oracle's support roadmap):

Java LTS Version	GA	End of life
25	September 2025	September 2033
21	September 2023	September 2031
17	September 2021	September 2029
11	September 2018	September 2026
8	March 2014	December 2030 (1)

⁽¹⁾ The Extended Support uplift fee will be waived for the period March 2022 - December 2030 for Java SE 8.

NB. See also Zulu's support roadmap.

[3] Using Bazel on Windows ↩

See also the Support matrix on the Bazel website.

Bazel LTS Version	GA	End of support
8.0.0	Late 2024	-
7.4.0	October 2024	December 2026
7.3.1	December 2023	December 2026
6.5.0	December 2022	December 2025
5.4.1	January 2022	January 2025

Read the page Builds on Windows of the Bazel website for tips to build with MSVC, Clang, Java or Python on a Windows machine.

For instance, for Visual Studio 2019, we set variable BAZEL_VC to the Visual C++ Build Tools installation directory:

> set "BAZEL_VC=C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC"

[4] JaCoCo and Java support ↩

JaCoCo version	Supported Java version	Depends on ASM
0.8.12 (March 2024)	21 and 22	9.7
0.8.11 (Oct 2023)	21 and 22	9.6
0.8.10.2 (April 2023)	19 and 20	9.5
0.8.9 (March 2023)	19 and 20	9.5
0.8.8 (April 2022)	17 and 18	9.2
0.8.7 (May 2021)	15 and 16	9.1
0.8.6 (Sept 2020)	14	8.2
0.8.5 (Oct 2019)	13	7.2
0.8.4 (May 2019)	12	7.1
0.8.3 (Jan 2019)	11	7.0
0.8.2 (Aug 2018)		6.3.2
0.8.1 (March 2018)	10
0.8.0 (Jan 2018)	9	6.0

[5] Scala 3 Next ↩

The attentive Scala 3 user will have noticed that the size of the Scala 3 software distribution has increased significantly with version 3.5.0.

Scala 3 Version	Archive size	Installation size
3.3.4 LTS	34 MB	38.6 MB
3.5.0 Next	70 MB	131 MB

That size increase of the Scala 3 software distribution comes from a big reorganization of its contents :

• scala-cli (91 MB) from VIRTUSLAB is now part of the distribution
• directory lib\ now contains only 3 JAR files: .
• directory maven2\ (40 MB) is new; this application specific Maven repository contains the Maven packages Scala 3 depends on.

The section "Class-Path Attribute" of the Java Platform Specification describes the usage the manifest attribute Class-Path. We present its usage in the manifest file lib\scala.jar\META-INF\MANIFEST.MF :

Manifest-Version: 1.0
Class-Path: ../maven2/org/scala-lang/scala3-interfaces/3.5.0/scala3-in
 terfaces-3.5.0.jar ../maven2/org/scala-lang/scala3-compiler_3/3.5.0/s
 cala3-compiler_3-3.5.0.jar ../maven2/org/scala-lang/scala3-library_3/
 3.5.0/scala3-library_3-3.5.0.jar ../maven2/org/scala-lang/tasty-core_
 3/3.5.0/tasty-core_3-3.5.0.jar ../maven2/org/scala-lang/modules/scala
 -asm/9.6.0-scala-1/scala-asm-9.6.0-scala-1.jar ../maven2/org/scala-sb
 t/compiler-interface/1.9.6/compiler-interface-1.9.6.jar ../maven2/org
 /jline/jline-reader/3.25.1/jline-reader-3.25.1.jar ../maven2/org/jlin
 e/jline-terminal/3.25.1/jline-terminal-3.25.1.jar ../maven2/org/jline
 /jline-terminal-jna/3.25.1/jline-terminal-jna-3.25.1.jar ../maven2/or
 g/scala-lang/scala-library/2.13.15/scala-library-2.13.15.jar ../maven
 2/org/scala-sbt/util-interface/1.9.8/util-interface-1.9.8.jar ../mave
 n2/org/jline/jline-native/3.25.1/jline-native-3.25.1.jar ../maven2/ne
 t/java/dev/jna/jna/5.14.0/jna-5.14.0.jar
 

[6] Downloads ↩

In our case we downloaded the following installation files (see section 1):

0.12.1-assembly (mill)                             ( 64 MB)
apache-ant-1.10.15-bin.zip                         (  9 MB)
apache-maven-3.9.9-bin.zip                         ( 10 MB)
bazel-7.4.0-windows-x86_64.zip                     ( 40 MB)
gradle-8.10.2-bin.zip                              (124 MB)
jacoco-0.8.12.zip                                  (  4 MB)
jitwatch-ui-1.4.9-shaded-win.jar                   ( 36 MB)
msys2-x86_64-20240727.exe                          ( 94 MB)
OpenJDK8U-jdk_x64_windows_hotspot_8u432b06.zip     ( 99 MB)
OpenJDK17U-jdk_x64_windows_hotspot_17.0.13_11.zip  (188 MB)
OpenJDK21U-jdk_x64_windows_hotspot_21.0.5_11.zip   (191 MB)
openjfx-17.0.13_windows-x64_bin-sdk.zip            ( 39 MB)
openjfx-17.0.13_windows-x64_bin-jmods.zip          ( 37 MB)
openjfx-21.0.5_windows-x64_bin-sdk.zip             ( 39 MB)
openjfx-21.0.5_windows-x64_bin-jmods.zip           ( 37 MB)
PortableGit-2.47.0-64-bit.7z.exe                   ( 60 MB)
sbt-1.10.3.zip                                     ( 17 MB)
scala-2.13.15.zip                                  ( 22 MB)
scala-cli-x86_64-pc-win32.zip                      ( 31 MB)
scala3-3.3.4.zip                                   ( 34 MB)
scala3-3.5.2.zip                                   (123 MB)

[7] PowerShell ↩

Command Prompt has been around for as long as we can remember, but starting with Windows 10 build 14971, Microsoft is trying to make PowerShell the main command shell in the operating system.

mics/November 2024 ▲