Strand sort

func merge(x, y) {
    var out = []
    while (x && y) {
        given (x[-1] <=> y[-1]) {
            when ( 1) { out.prepend(x.pop) }
            when (-1) { out.prepend(y.pop) }
            default   { out.prepend(x.pop, y.pop) }
        }
    }
    x + y + out
}

func strand(x) {
    x || return []
    var out = [x.shift]
    if (x.len) {
        for i in (-x.len .. -1) {
            if (x[i] >= out[-1]) {
                out.append(x.pop_at(i))
            }
        }
    }
    return out
}

func strand_sort(x) {
    var out = []
    while (var strd = strand(x)) {
        out = merge(out, strd)
    }
    return out
}

var a = 10.of { 100.irand }
say "Before: #{a}"
say "After: #{strand_sort(a)}"

Output:

Before: 24 62 29 95 11 21 46 3 23 20
After: 3 11 20 21 23 24 29 46 62 95