scala-cli Cheatsheet

Oct 21, 2021 · 2 min read

Compile file(s) / folder

scala-cli compile Hello.scala

# Compile with dependent classes
scala-cli compile Hello.scala Includes.scala

# Compiles all Scala files in the folder
scala-cli compile .

Compile and run Scala files / folder

# Compile and run `main` in Hello.scala
scala-cli run Hello.scala

# `run` command is the default and may be omitted for running the class
scala-cli Hello.scala

# Compile and run `main` with all associated files listed
scala-cli Hello.scala Utils.scala

# Compile the whole directory and run `main`
scala-cli .

Running Scripts

HelloScript.sc

#!/usr/bin/env scala-cli
println("What a wonderful world!")

scala-cli run HelloScript.sc

Running gist

scala-cli https://gist.github.com/<user-handle>/<gist-id>

Specify Dependencies

scala-cli compile Hello.scala --dependency org.typelevel::cats-core:2.6.1

scala-cli compile Hello.scala --jar /path/to/library.jar

Watch for changes

scala-cli --watch .

scala-cli --watch Hello.scala

scala-cli compile --watch Hello.scala

Specify Scala Version

scala-cli compile --scala 2.13.6 Hello.scala

Picks the highest corresponding stable Scala version

scala-cli compile --scala 2.12 Hello.scala
scala-cli compile --scala 2 Hello.scala
scala-cli compile --scala 3 Hello.scala

Compiler Options

scala-cli compile Hello.scala -Xlint:unused

Compiler Plugins

scala-cli compile \
  --scala 2.13 \
  --compiler-plugin com.olegpy:better-monadic-for:0.3.1 \
  Hello.scala

Specify main

If there is more than one main found:

➜ scala-cli .

Compiling project (Scala 3.0.2, JVM)
Compiled project (Scala 3.0.2, JVM)
Found several main classes: Hello, Includes

… in that case:

scala-cli --main-class Includes .

Compiling project (Scala 3.0.2, JVM)
Compiled project (Scala 3.0.2, JVM)
Includes says hi!

Specify JVM

scala-cli --jvm graalvm:21 .

Packaging

Create a distributable library (eg. Maven)

scala-cli package --library Hello.scala -o hello.jar
javap -cp hello.jar hello.Hello

Create a light-weight executable/launcher JAR

scala-cli package Hello.scala -o hello

Create an heavy-weight executable assembly

scala-cli package --assembly Hello.scala -o hello

Create an executable and package into a docker image

scala-cli package --docker Hello.scala --docker-image-repository hello-docker

Create a native executable

scala-cli package --native Hello.scala -o hello-native

scala-cli package --native -S 2.13 --main-class Hello . -o hello-native

REPL

➜ scala-cli repl .
Compiling project (Scala 3.0.2, JVM)
Compiled project (Scala 3.0.2, JVM)
Warning: found classes defined in the root package (Hello, Hello$, Includes, Includes$, test, test$, test_sc, test_sc$). These will not be accessible from the REPL.

scala> Includes.run(Array.empty)
Includes says hi!

scala> Hello.main(Array.empty)
Scala says Hello!  **  2021-10-22T11:23:47.327515

scala> Includes.echo("1234567890")
You said: 1234567890

Scalafmt

There are some known limitation(s); hopefully for the time being.

scala-cli fmt

scala-cli fmt --check

scala-cli fmt --dialect scala212

Clean

Removed all generated files (primarily those in .scala/)

scala-cli clean .