Course of Raku / Functional, concurrent, reactive, and web programming / Functional programming / Lazy and infinite sequences / Exercises / Powers of three

Solution: Powers of three

Here is a possible solution to the task.

Code

say (1, * * 3 ... *).head(5);

🦋 You can find the source code in the file powers-of-two.raku.

Output

(1 3 9 27 81)

Comments

1. The closure * * 3 is the rule for the next term: take the current one and multiply by three. Giving the rule explicitly is more reliable than letting the operator guess from the first few terms.

2. The * endpoint makes the series infinite, and .head(5) takes the first five.

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