Seven Languages in Seven Weeks: Scala, Day 2

After a bumpy start with Scala on Day 1, I’ve moved onto the second day of Scala in Seven Languages in Seven Weeks.

Scala, Day 2: Thoughts

The second Scala chapter shifts gears to functional programming. Unfortunately, I was impatient on Day 1 and had already looked up all of these concepts (and some more) to build a Tic Tac Toe game. As a result, I breezed through the chapter.

On a side note, I was using Scala on a personal project and rewrote some Java code using Scala. As much as I complained yesterday about Scala’s complexity, the slow compiler, and poor IDE support, I must admit one thing: the resulting code was noticeably cleaner, shorter, and easier to read.

The language is certainly not perfect, but I need to make sure I’m not missing the forrest for the trees: it’s still likely a vastly superior alternative to Java.

Scala, Day 2: Problems

The functional programming problems in this chapter were extremely simple. I burned through them in a few minutes and present the code without further comment:

String foldLeft

Use foldLeft to compute the total size of a List of Strings.

val list = List("foo", "bar", "blah")
val totalLength = list.foldLeft(0)(_ + _.length)
println("The total length of " + list + " is " + totalLength)

Censorship

Write a Censor trait with a method that will replace “curse” words with “clean” alternatives. Read the curse words and alternatives from a file and store them in a Map.

import collection.mutable.HashMap
 
trait Censor {
  val curseWords = new HashMap[String, String]()
 
  io.Source.fromFile("censor.txt").getLines().foreach { (line) =>
    val parts = line.split(": ")
    curseWords += parts(0) -> parts(1)
  }
 
  def censor(s: String) = curseWords.foldLeft(s)((prev, curr) => prev.replaceAll(curr._1, curr._2))
}
 
class Text(s: String) extends Censor {
  def value = s
 
  def censoredValue = censor(s)
}
 
val text = new Text("Shoot, I forgot my Darn traits again")
println("Original String: " + text.value)
println("Censored String: " + text.censoredValue)

Output:

Shoot: Pucky
Darn: Beans

On to day 3

Learn about pattern matching and actors in Scala, Day 3.