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Configuration

Scala CLI can be configured in two ways:

  • on the command-line
  • directly in .scala and .sc files

Parameters on the command line take precedence over parameters in sources. That way, you can quickly override parameters from the command line.

warning

The configuration options and syntax in .scala (and .sc) files is likely to evolve in the future.

Command-line​

Pass --help to any sub-command of Scala CLI to list its options:

scala-cli --help
scala-cli --power package --help

As an example of command line configuration, one thing you can do with Scala CLI command line options is to specify the Scala version:

@main def test = println("test")
scala-cli --scala 3.0.0 Test.scala
test

Another thing you can do is to specify dependencies:

scala-cli --dependency org.typelevel::cats-core:2.10.0 Test.scala
test

The reference documentation lists all of the available options.

In .scala and .sc files​

Configuration information can also be put in .scala and .sc files using special imports, and the using directive.

Using directives​

Scala CLI can be configured inside .scala files. This is achieved by specifying using directives inside comments at the top of a .scala file, before any package or import statement:

//> using scala 2.13
//> using platform scala-js
//> using options -Xasync

// package and import statements follow here ...

The reference documentation lists all available using directives.

Also, there are some directives which only target tests, like using test.dep. Those can be useful when defining configuration specific to your test runs.

//> using test.dep com.lihaoyi::utest::0.8.1

More details can be found in the using directives guide.

Special imports​

Dependencies can be added right from .scala and .sc files with using directives:

//> using dep com.lihaoyi::upickle::3.1.2
//> using dep com.lihaoyi::pprint::0.8.1
import ujson._

Both import $ivy and import $dep are not supported.