I recently picked up a copy of Seven Languages in Seven Weeks by Bruce A Tate. The book is a survey of seven very different programming languages: Ruby, IO, Prolog, Scala, Erlang, Clojure, and Haskell. For each language, the goal is to give you just enough of a taste that you can see what makes it unique, what its strengths and weaknesses are, and the mindset and philosophy behind it.

Seven Languages in Seven Weeks
Seven Languages in Seven Weeks

Each section of the book focuses on a different language and includes coding problems for the reader to try at home. I’ve decided to record my my solutions to the problems and thoughts about each language in my blog. Today, we’ll start with Ruby.

Ruby, Day 1: Thoughts

I’ve used Ruby fairly extensively the last few years, including several Ruby on Rails apps (Resume Builder, Veterans Hackday) and a number of utility scripts. There is a lot to like about Ruby - the concise & clean syntax, incredible flexibility, expressiveness, powerful DSLs - but my favorite part is the central tennet of the language, as expressed by its creator:

Ruby is designed to make programmers happy.

Yukihiro Matsumoto

The language isn’t built for speed, concurrency, or any particular feature set. Its central “success metric” is programmer happiness and productivity, which are, arguably, the biggest bottlenecks in most projects.

Ruby, Day 1: Problems

The “Day 1” Ruby chapter focused on the very basics of the language, so I didn’t learn anything new. The problems are extremely simple and basic, but for completeness, here are my solutions:

Hello, World

Print the string “Hello, world”.

puts "Hello, world"

Hello, Ruby

For the String “Hello, Ruby”, find the index of the word “Ruby”.

"Hello, Ruby".index "Ruby"

Print your name ten times.

10.times { puts "Jim" }

Print the string “This is sentence number 1” where the number 1 changes from 1 to 10.

1.upto(10) { |i| puts "This is sentence number #{i}" }

Random Number

Write a program that picks a random number. Let a player guess the number, telling the player whether the guess is too high or too low.

to_guess = rand(10) + 1
puts "Try to guess a number between 1 and 10."
  print "Enter your guess: "
  guess = gets.to_i
  puts "Too low!" if guess < to_guess
  puts "Too high!" if guess > to_guess
end while guess != to_guess
puts "Correct!"

Ruby vs. Java

Coming from a Java background, every time I see Ruby, I’m amazed at how concise and readable it is. There is far less boilerplate: you don’t have to wrap everything in classes and methods, no semi-colons, far fewer curly braces, and so on. Everything is an object and there are countless helper functions, all with intuitive names: even if you’ve never used Ruby, it’s easy to guess the effects of 10.times or 1.upto(10). Whereas in the Java world, libraries seem to compete on having every bell, whistle, and tuning knob, in the Ruby world, libraries focus much more on having the simplest, easiest, one-line-and-you’re-done API possible.

For comparison, I implemented the number guessing game in Java:

import java.util.Random;
import java.util.Scanner;
public class GuessNumber {
  public static void main(String[] args) {
    Random generator = new Random();
    int toGuess = generator.nextInt(10) + 1;
    int guess;
    Scanner scanner = new Scanner(System.in);
    try {
      System.out.println("Try to guess a number between 1 and 10.");
      do {
        System.out.print("Enter your guess: ");
        guess = scanner.nextInt();
        if (guess < toGuess) {
          System.out.println("Too low!");
        } else if (guess > toGuess) {
          System.out.println("Too high!");
      } while (guess != toGuess);
    } finally {

It’s has more than twice the number of lines of code as the Ruby version (and I kept opening curly braces on the same line!) and even though I’ve been doing Java for a very long time, it still took longer to write. Of course, there are many other trade-offs at play here, but they key thing to think about is the golden rule of programming:

Programs must be written for people to read, and only incidentally for machines to execute.

Structure and Interpretation of Computer Programs

Ruby has its downsides, but it is one of the best languages I’ve seen for writing code that others can read, understand, and maintain for a long time after.

Ruby, Continued

The Ruby explorations continue on Ruby, Day 2.