Course of Raku / Addendum 🆕 / Flow and functions / Control flow and logic / Exercises / Kind of triangle

Solution: Kind of triangle

Here is a possible solution to the task.

Code

sub kind($a, $b, $c) {
    return 'invalid' unless $a + $b > $c && $a + $c > $b && $b + $c > $a;

    given ($a, $b, $c).Set.elems {
        when 1  { 'equilateral' }
        when 2  { 'isosceles' }
        default { 'scalene' }
    }
}

for (3, 3, 3), (3, 3, 5), (3, 4, 5), (1, 2, 10) -> ($a, $b, $c) {
    say "$a $b $c: { kind($a, $b, $c) }";
}

🦋 You can find the source code in the file triangle-kind.raku.

Output

3 3 3: equilateral
3 3 5: isosceles
3 4 5: scalene
1 2 10: invalid

Comments

The unless guard rejects side lengths that break the triangle inequality before any classification happens.
The number of distinct side lengths tells the kind: one means all equal (equilateral), two means exactly one pair equal (isosceles), three means all different (scalene).
Destructuring the loop variable as -> ($a, $b, $c) unpacks each inner list straight into three named sides.

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