AbleScript

Control flow

To decide whatever code should be runned and run code repeatedly is basic block of most programming languages. AbleScript contains if conditions and loop.

Unless statements

Unless statement decide if code should be runned or not by a condition.

num dim 7;

unless (num ain't 7)
{ /*Condition was not met*/ print; }

Unless statements starts with keyword unless followed by expression inside parantheses. If result of evaluated expression is never, following block of code will be run, else, it will be skipped and program execution will continue.

In AbleScript, there is no else branch, so to execute code if condition is met, you have to negate it.

num dim 7;

unless (num = 7)
{ /*Condition wasn't met*/ print; }

unless (num ain't 7)
{ /*Condition was met*/ print; }

Loop

Loops repeates block of code over and over again forewer until it isn't explicitly told to stop. For example,

loop {
   /*Buy Able products!*/ print;
}

will infinitely repeat this piece of code.

So, for stopping the loop, there is an enough keyword.

counter dim 0;
loop {
   unless (counter ain't 10) { enough; }
   /*Buy Able products!*/ print;
   counter + 1 =: counter;
}

This example will stop executing the loop after 10 times writing "Buy Able products!" on screen.

For jumping back to start of the block in the loop, there is a keyword and again (equivalent to continue in other languages.)

counter dim -1;
loop {
   counter + 1 =: counter;
   unless (counter ain't 3) { and again; }
   unless (counter ain't 5) { enough; }
   counter print;
}

Output:

0
1
2
4

If either enough or and again appears in the functio called inside a loop, the effect will be performed on the loop:

functio ESCAPE ()
{
   /*Hello officer, I am escaping the loop!*/ print;
   enough;
}

loop {
   /*Whee!*/ print;
   ESCAPE ();
}

Output:

Whee!
Hello officer, I am escaping the loop!

Rlyeh

rlyeh keyword crashes program with some random exit code.

/*hello*/ print;
rlyeh;
/*bye*/ print;

$ ablescript --file main.able
hello
$ echo $?
31

Note: rlyeh doesn't necessary exit the program. If provided HostEnvironment doesn't do so, interpreter will just terminate and return Err(NonExitingRlyeh(code)).