Problem running `@main` methods with command line arguments

Compiler version

3.1.1

Minimized code

// In file echoargs.scala
@main def echo(args: String*) =
  println(args.mkString(" "))

Output

First compile

$ scalac echoargs.scala

Then run the main method:

$ scala echo hello world
echo hello world hello world

Expectation

$ scala echo hello world
hello world

Edit: this was the output using the scala command of 3.0.2

[som-snytt]

$ scala echo hello world
echo hello world hello world

Crossword just had clue “hello hello hello, e.g.” for “echo”.

[spamegg1]

If we can go 6 months without using command line args, then maybe we don’t need command line args.

The book told me to do it! (Prog in Scala 5th ed) It’s used to show the power of type classes:

How does Scala know how to turn the command line string “3” into an Int 3 ? It uses a typeclass named FromString ,