Script to list Scala Book MD filenames in their order

CreateListOfFilenamesInOrder.sc

//> using scala "3"

/**
 * This is a script to create the `SortedListOfMDFilenames` file
 * from the existing MD files. It assumes that all of those
 * files have a `num: nn` field.
 * 
 * Run me like this:
 *     scala-cli CreateListOfFilenamesInOrder.sc
 *
 */

// the directory where all the MD files are located
val DIR = "/Users/al/Projects/docs.scala-lang/_overviews/scala3-book"

// [0] the necessary functions
def readFile(filename: String): List[String] =
    io.Source.fromFile(filename)
             .getLines
             .toList

import java.io.File
def getListOfFilesInDir(dir: File, extensions: List[String]): List[File] =
    dir.listFiles.filter(_.isFile).toList.filter { file =>
        extensions.exists(file.getName.endsWith(_))
    }


// [1] get a list of the MD files
val okFileExtensions = List("md")
val filesInDir = getListOfFilesInDir(File(DIR), okFileExtensions)
val filenamesInDir = filesInDir.map(f => f.toString)

// [2] from those MD files, build a `Map[FileName, FileNumber]`
val map = scala.collection.mutable.Map[String, Int]()
for fileName <- filenamesInDir do
    val lines = readFile(fileName)
    val matchingLine = lines.filter(_.startsWith("num: "))(0)
    val fileNumber = matchingLine.drop(5).trim.toInt
    map += (fileName -> fileNumber)

// [3] sort the Map and print the filenames by their `num:` value
val sortedMap = scala.collection.immutable.ListMap(map.toSeq.sortBy(_._2):_*)
for (k, v) <- sortedMap do
    val fname = File(k).getName
    println(s"$fname")
    // debug: println(s"$fname \t $v")