Course of Raku / Essentials / The MAIN function

Reading command-line arguments

The MAIN function is handy not only to locate the start of the program explicitly, but also because of its arguments, which get the values passed in the command line.

There are two ways of reading command-line arguments. One of them is via the @*ARGS array, which we already used. Let us examine the second method now.

Consider a program that adds up two numbers.

sub MAIN($a, $b) {
    say $a + $b;
}

You can run the program in the following way. The program prints the sum of its two arguments:

$ raku t.raku 123 45
168

As any other function, the MAIN function can have default values for some (or even all) of its arguments. For example:

sub MAIN($a, $b = 100) {
    say $a + $b;
}

If the second argument is not provided, the default value is used:

$ raku t.raku 15
115

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