Any real piece of music is going to contain more than one note. Type the following code in the Code Editor and click on Run. What do you hear?

play 60
play 65
play 72

That might not have sounded the way you expected! All the notes played at the same time. Sonic Pi will play every note it sees until it reaches a sleep command, upon which it waits for a certain amount of time and then continues. This is useful when we want to play multiple notes at once, but to create a tune, we need them all to be separate. Put a sleep command after each play command, like this:

play 60
sleep 1
play 65
sleep 1
play 72
sleep 1

That's better! All the notes now play one after another. The number after the sleep command is the number of seconds to wait before playing the next note (or notes). Again, we can use any number we like, and the number can be different for each sleep command.

Now, music is largely based on repetition, so let's learn how to create loops in Sonic Pi. It's very simple—add a loop do and an end around the code that we want to repeat, like this:

loop do
  play 60
  sleep 1
  play 65
  sleep 1
  play 72
  sleep 1
end

The do and end tell Sonic Pi which lines of code are in the code block and the loop tells it what should be done with the block. In this case, we want the code to repeat forever. We don't need to indent the code within the block (as we do in Python), but it helps make the code more readable, especially when we have complex structures such as loops within loops. At any time, you can click on the Align button at the top of the window and it will choose what it thinks is the best indentation for your code.

If you like to repeat the code a fixed number of times, replace loop with any number followed by .times. For example, the first line can be 10.times do if you want to repeat the code ten times.

Finally, let's tweak our code to create a random tune. The first thing we're going to do is put all the notes we want to play into a list. We can do this in exactly the same way as we did in Python. Here's a list that contains the three notes from the previous example:

[60, 65, 72]

See how we separate each number in the list with commas, and we wrap the whole thing with square brackets. You can change any of these numbers or add new ones if you like. To get a random number from our list, we will use the choose function that Sonic Pi provides. Here is a new code block to put inside our loop:

  play choose([60, 65, 72])
  sleep 1

If you run this code, you should hear a sequence of random notes taken from the list.