Nested templated data

Explicitly not using strings, using one data structure to fill in another. Since it isn't a string, the output format removes the newlines from the template; line feed (white space in general) isn't particularly significant in Raku data structures. It does preserve the nesting though. In the second example, payload "buckets" that don't exist result in an undefined value being inserted; by default: Any.

say join "\n  ", '##PAYLOADS:', |my @payloads = 'Payload#' X~ ^7;

for [
     (((1, 2),
       (3, 4, 1),
       5),),

     (((1, 2),
       (10, 4, 1),
       5),)
    ] {
    say "\n      Template: ", $_.raku;
    say "Data structure: { @payloads[|$_].raku }";
}

Output:

##PAYLOADS:
  Payload#0
  Payload#1
  Payload#2
  Payload#3
  Payload#4
  Payload#5
  Payload#6

      Template: $(((1, 2), (3, 4, 1), 5),)
Data structure: ((("Payload#1", "Payload#2"), ("Payload#3", "Payload#4", "Payload#1"), "Payload#5"),)

      Template: $(((1, 2), (10, 4, 1), 5),)
Data structure: ((("Payload#1", "Payload#2"), (Any, "Payload#4", "Payload#1"), "Payload#5"),)