Course of Raku / Essentials / Loops

Using repeat

The while and until blocks may never be executed if the condition is initially False. In contrast, the repeat block is always executed at least once. The stop condition is checked after the code block. You use the same words while or until for the test.

Consider this program.

my $x = 100;
repeat {
    $x = prompt 'Enter a number: ';
    say "You entered $x.";
} while $x <= 10;
say "$x is bigger than 10.";

The $x variable is initially set to 100, and the while condition is checking whether $x is less than or equals to 10. With the given value of the variable, the condition is already False, but the code block is still executed first.

$ raku t.raku
Enter a number: 10
You entered 10.
Enter a number: 20
You entered 20.
20 is bigger than 10.

Let us modify the program to use until instead.

my $x = 0;
repeat {
    $x = prompt 'Enter a number: ';
    say "You entered $x.";
} until $x > 10;
say "$x is bigger than 10.";

Run it to confirm it works as expected:

$ raku t.raku
Enter a number: 5
You entered 5.
Enter a number: 15
You entered 15.
15 is bigger than 10.

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