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Piping

Instead of passing paths to your sources, you can also pipe your code via standard input:

echo '@main def hello() = println("Hello")' | scala-cli _
Hello

Wildcards​

The _ wildcard implies that the piped code is a standard Scala app. It is also possible to pass a script or Java code, when using the appropriate wildcard. The available options are as follows:

  • for standard Scala code use _, _.scala or -.scala;
  • for Scala scripts use -, _.sc or -.sc;
  • for Java code use _.java or -.java.

Examples​

  • scripts
echo 'println("Hello")' | scala-cli _.sc
Hello
  • Scala code
echo '@main def hello() = println("Hello")' | scala-cli _.scala
Hello
  • Java code
echo 'class Hello { public static void main(String args[]) { System.out.println("Hello"); } }' | scala-cli _.java
Hello

Mixing piped sources with on-disk ones​

It is also possible to pipe some code via standard input, while the rest of your code is on-disk.

echo 'case class HelloMessage(msg: String)' > HelloMessage.scala
echo '@main def hello() = println(HelloMessage(msg = "Hello").msg)' | scala-cli _ HelloMessage.scala
Hello

You can even refer to code from piped scripts, when needed. A piped script can be referred to by its wrapper name stdin, as in the example below.

echo '@main def main() = println(stdin.message)' > PrintMessage.scala
echo 'def message: String = "Hello"' | scala-cli PrintMessage.scala _.sc
Hello