REPL

The repl command starts a Scala REPL, which lets you interactively run your code and inspect its results:

scala-cli repl

scala> println("Hello Scala")
Hello Scala

scala> :exit

Scala CLI by default uses the normal Scala REPL.

If you prefer to use the Ammonite REPL, specify --amm to launch it rather than the default REPL:

scala-cli repl --amm

Loading...
Welcome to the Ammonite Repl 2.4.0-23-76673f7f (Scala 3.0.2 Java 11.0.11)
@ println("Hello ammonite")
Hello ammonite
@ exit
Bye!

The repl command accepts the same arguments as the compile command. It first compiles any provided sources, and then exposes those results and any provided dependencies to the REPL session:

mylibrary/Messages.scala

package mylibrary

object Messages {
  def message = "Hello"
  def print(): Unit = println(message)
}

scala-cli repl mylibrary/Messages.scala

Compiling project (Scala 3.0.2, JVM)
Compiled project (Scala 3.0.2, JVM)
scala> import mylibrary._

scala> Messages.print()
Hello

scala> :quit

Inject code as JAR file in class path

If your application inspects its class path, and requires only JAR files in it, use --as-jar to put the Scala CLI project in the class path as a JAR file rather than as a directory:

scala-cli repl Foo.scala --as-jar