Course of Raku / Advanced / Control flow / gather and take / Exercises / Squares

Solution: Squares

Here is a possible solution to the task.

Code

my @squares = gather for 1..6 {
    take $_ ** 2 if $_ %% 2;
};

say @squares;

🦋 You can find the source code in the file squares.raku.

Output

[4 16 36]

Comments

The if $_ %% 2 guard decides whether to take, and $_ ** 2 decides what to take. Only the even numbers 2, 4, 6 pass the guard.
Their squares 4, 16, 36 are the only values handed to take, so gather collects exactly those. Doing the filtering and the transforming together in one take is something a plain map cannot express as cleanly.

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