I thought I’d have a little fun today, and show different ways to declare multiple variables on one line. These aren’t the most useful or common things to do, but they’re interesting, and I know I learned at least one thing while looking into this.

You can define multiple fields on one line, separated by commas, as long as they are all the same type and have the same value:

Out of curiosity about Scala’s file-reading performance, I decided to write a “line count” program in Scala. One obvious approach was to count the newline characters in the file:

// took 101 secs (10M lines)
// work on one character at a time
def countLines1(source: Source): Long = {
  var newlineCount = 0L
  for {
    c <- source
    if c.toByte == NEWLINE
  } newlineCount += 1
  newlineCount
}

As the comment shows, this took 101 seconds to read a file that has 10M lines. (An Apache access log file for this website.)