Scala simple examples

control.scala

// Returns value given the case. If it does not have an else statement, it will always return Unit ()
val filename =
  if (!args.isEmpty)
    args(0)
  else
    "default.txt"

// Always returns Unit()
while (a != 0) {
  val temp = a
  a = b % a
  b = temp
}

// Always returns Unit()
var line = ""
do {
  line = readLine
  println("Read: " + line)
} while (!line.isEmpty)

// Always returns Unit()
val filesHere = (new java.io.File(".")).listFiles
for (file <- filesHere)
  println(file)
  
for (i <- 1 to 5)
  println("Iteration " + i)
  
// Filtering a for
for (file <- filesHere; if file.getName.endsWith(".scala"))
  println(file)
  
// Without semicolons
for {
  file <- filesHere
  if file.isFile
  if file.getName.endsWith(".scala")
} println(file)

// Nested for
def grep(pattern: String) =
  for {
    file <- filesHere
    if file.getName.endsWith(".scala")
    line <- fileLines(file)
    trimmed = line.trim
    if trimmed.matches(pattern)
  } println(file + ": " + trimmed)
  grep(".*gcd.*")
  
val url =
  try {
    new URL(path)
  }
  catch {
    case e: MalformedURLException =>
      new URL("http://www.scala-lang.org")
  } 
  finally {
  }
  
// Match
val firstArg = if (args.length > 0) args(0) else ""
firstArg match {
  case "salt" => println("pepper")
  case "chips" => println("salsa")
  case "eggs" => println("bacon")
  case _ => println("huh?")
}

FileMatcher.scala

object FileMatcher {
  private def filesHere = (new java.io.File(".")).listFiles
  
  private def filesMatching(matcher: String => Boolean) =
    for (file <- filesHere; if matcher(file.getName))
      yield file
      
  def filesEnding(query: String) =
    filesMatching(_.endsWith(query))
  
  def filesContaining(query: String) =
    filesMatching(_.contains(query))
  
  def filesRegex(query: String) =
    filesMatching(_.matches(query))
    
}

Taken from Programming in Scala by Martin Odersky, Lex Spoon and Bill Venners