README.md

Introduction

Process.scala is my attempt at creating an application skeleton for a command-line application that has to process (in this case) a single JSON file.

I'm new to Scala and would love feedback on the proper way to do this.

Design Comments

• I know I should have a package statement at the top. This is just test code for now.
• For a simple application that just processes one or two inputs, I'm not interested in using a third-party package to parse command-line arguments. Pointers are appeciated, however, especially to routines present in the libraries that ship with Scala.
• As you can see, this template does not actually process the input file. That's a feature, not a bug.

Process.scala

import java.nio.file.{Paths,Files}

object Process {

  def fileExists(path: String): Boolean = {
    Files.exists(Paths.get(path))
  }

  def validInput(args: Array[String]): Boolean = {
    val onlyOne = args.length match {
      case 1 => true
      case _ => false
    }
    val validExtension = args(0) matches ".*[.]json"
    onlyOne && validExtension && fileExists(args(0))
  } 

  def main (args: Array[String]) = {
    val isValid = validInput(args)
    if (!isValid) {
      println("Usage: scala Process.scala <input.json>")
      System.exit(1)
    }
    val inputFile = args(0)
    println(s"Input File: $inputFile")
    System.exit(0)
  }
}