When creating a program in Perl 6, it is important to understand that controlling the program flow is a little trickier than simply following the instructions of the code. There are special types of code blocks that are automatically called by the compiler at different phases of the compilation and the execution processes. Those blocks are called phasers.
We mentioned two of them, BEGIN and CHECK, in Chapter 1, What is Perl 6?, when we talked about the -c command-line option of the compiler. Now, let's take a look at the rest.
Syntactically, phasers are blocks of code in curly braces preceded by a phaser name. The following table summarizes the different phasers that exist in Perl 6. Some of the phasers are executed at compile-time before the rest of the program is compiled and executed. Some are called at runtime.
| Phaser name | Execution stage | Actions |
| BEGIN | compile... |