Commands

Commands let you tell BackTalk what to do. In BackTalk, they look sort of like sentences. One of the most commonly used commands in BackTalk is with $ as $. Here's an example of how you would use it:

with $my_dog as $bingo

or you could use it like this:

with $my_best_friend as $suzy

These two lines each set up a new reference. The first makes the reference $my_dog refer to the same thing as the reference $bingo. Remember, a reference is a name, so you now have two names for your dog Bingo. You can refer to Bingo as $my_dog or as $bingo. When we said with $ as $ before, this was really a shorthand to tell you that there is a command that starts with, followed by a reference of your choosing, followed by as, and then another reference of your choosing.

Other Commands

There can be many commands available to you as you write BackTalk code. In the example below, you can use the commands

• with $ as $
• say hi to $
• listen to $

• print $

  Try it out and see what happens!

-- CommandsExample
print "BackTalk is fun!"

with $my_dog as $bingo
say hi to $bingo
say hi to $my_dog
say hi to $suzy

listen to $suzy

Parameters

In the example above, you may have noticed that you can use more than just references when giving a command. You can use any of the BackTalk data types. Whatever extra information you add to the command is called a parameter. Check out the example below to see how we can use print $ with different parameters.

-- CommandsExample
print "parameters are cool!"
print 1
print $suzy
print true
print (! true)

with $x as 4
print ($x + 4 * 7 - 4)

Sometimes, you may be required to use parentheses ( ) to make it clear what is part of a command and what is a parameter. The best rule to follow is that if the parameter is any sort of calculation (like 3 + 4 or $x & false), you should put parentheses around it.

Command Bodies

Some commands have a form that allows them to include a section of BackTalk code. with $ as: is an example of this. It runs all of the commands it is given, and then sets the reference to whatever the result is. To determine what lines of code belong to a command, BackTalk looks at the number of spaces at the start of the line. Anything with more spaces belongs to the most recent command that ends with :.

In the following example, with $ as: is used to set the reference $x to the result of a series of computations.

-- CommandsExample
with $me_and_bingo as:
    with $my_height as 160
    with $bingos_height as 30

    $my_height + $bingos_height

print $me_and_bingo