Course of Raku / Functional, concurrent, reactive, and web programming / Concurrent programming / Hyper and race 🆕 / Exercises / Hyper with a filter

Solution: Hyper with a filter

Here is a possible solution to the task.

Code

say (1..20).hyper.grep(* > 10).map(*²);

🦋 You can find the source code in the file hyper-filter.raku.

Output

(121 144 169 196 225 256 289 324 361 400)

Comments

1. *² is just Raku’s superscript spelling of * ** 2: the ² is a postfix power operator, so *² is a WhateverCode that squares its argument. Write * ** 2 if you prefer.

2. .hyper parallelises the whole chain — the grep that keeps the numbers over 10 and the map that squares them — while preserving order.

3. Because the order is kept, the squares come back in the same sequence as their inputs (11², 12², …, 20²), giving (121 144 169 196 225 256 289 324 361 400).

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