A few simple Duby examples, taken from the examples dir on Oct 27, 2009.

Fibonacci

Identical to Ruby, except for the argument type declaration

 def fib(a:int)
   if a < 2
     a
   else
     fib(a - 1) + fib(a - 2)
   end
 end

Fractal benchmark

Also identical to Ruby, other than the type decl in iterate.

 import java.lang.System
 
 def run
   puts "Rendering"
   y = -39.0
   while y <= 39.0
     puts
     x = -39.0
     while x <= 39.0
       i = iterate(x/40.0,y/40.0)
       if (i == 0)
         print "*"
       else
         print " "
       end
       x += 1
     end
     y += 1
   end
   puts
 end
 
 def iterate(x:double,y:double)
   cr = y-0.5
   ci = x
   zi = 0.0
   zr = 0.0
   i = 0
 
   result = 0
   while true
     i += 1
     temp = zr * zi
     zr2 = zr * zr
     zi2 = zi * zi
     zr = zr2 - zi2 + cr
     zi = temp + temp + ci
     if (zi2 + zr2 > 16)
       result = i
       break
     end
     if (i > 1000)
       result = 0
       break
     end
   end
 
   result
 end
 
 i = 0
 while i < 10
   start = System.currentTimeMillis
   run
   puts "Time: " + (System.currentTimeMillis - start) / 1000.0
   i += 1
 end

Simple Swing application

Identical to Ruby (JRuby) other than "implements" instead of "include" for the interface impl and the use of a JButton cast in the actionPerformed implementation.

 import javax.swing.JFrame
 import javax.swing.JButton
 import java.awt.event.ActionListener
 
 frame = JFrame.new "Welcome to Duby"
 frame.setSize 300, 300
 frame.setVisible true
 
 button = JButton.new "Press me"
 frame.add button
 frame.show
 
 class AL; implements ActionListener
   def initialize; end
   def actionPerformed(event)
     JButton(event.getSource).setText "Duby Rocks!"
   end
 end
 
 button.addActionListener AL.new