Command Line Flags in Scala

Here’s the translation of the Go code example to Scala, with explanations in Markdown format suitable for Hugo:

import scala.collection.mutable.Map

object CommandLineFlags {
  def main(args: Array[String]): Unit = {
    // In Scala, we can use a library like scopt for command-line parsing.
    // For this example, we'll implement a simple parser ourselves.
    val flags = Map[String, Any]()
    
    // Define default values
    flags("word") = "foo"
    flags("numb") = 42
    flags("fork") = false
    flags("svar") = "bar"

    // Parse command-line arguments
    args.sliding(2, 2).foreach {
      case Array("--word", value) => flags("word") = value
      case Array("--numb", value) => flags("numb") = value.toInt
      case Array("--fork", _) => flags("fork") = true
      case Array("--svar", value) => flags("svar") = value
      case _ => // Ignore unrecognized flags
    }

    // Print the parsed options
    println(s"word: ${flags("word")}")
    println(s"numb: ${flags("numb")}")
    println(s"fork: ${flags("fork")}")
    println(s"svar: ${flags("svar")}")
    println(s"tail: ${args.filter(!_.startsWith("--")).mkString(" ")}")
  }
}

This Scala program demonstrates a simple implementation of command-line flag parsing. Here’s how it works:

1. We use a mutable Map to store our flag values. This is similar to how the Go example uses pointers to store flag values.

2. We set default values for our flags in the flags map.

3. We parse the command-line arguments using a simple pattern matching approach. This is a basic implementation and doesn’t handle all cases that a full-featured flag parsing library would.

4. After parsing, we print out the values of the flags and any remaining arguments (the “tail”).

To run this Scala program, you would typically use the Scala Build Tool (sbt) or compile it directly with the Scala compiler. Here’s how you might run it:

$ scala CommandLineFlags.scala --word=opt --numb=7 --fork --svar=flag
word: opt
numb: 7
fork: true
svar: flag
tail: 

If you omit flags, they will keep their default values:

$ scala CommandLineFlags.scala --word=opt
word: opt
numb: 42
fork: false
svar: bar
tail: 

You can also provide positional arguments:

$ scala CommandLineFlags.scala --word=opt a1 a2 a3
word: opt
numb: 42
fork: false
svar: bar
tail: a1 a2 a3

Note that this is a simplified version of command-line parsing. In a real Scala application, you would typically use a library like scopt or decline for more robust and feature-rich command-line parsing.