Example shell script showing that Scala code really just compiles to Java and the resulting code can be run from Java if you include the scala-library.

gistfile1.txt

rm -f *.class
rm -rf *.scala

echo 'object HelloWorld extends App{ println("hello world")}' > hw.scala

echo "## Scala source created"
cat hw.scala

echo "## Compiling Scala class"
scalac hw.scala

echo "## Disassembled Java"
javap HelloWorld

echo "## Running Scala from scala"
scala HelloWorld 

echo "## Running Scala from java"
java -cp ./scala-library.jar:. HelloWorld