Recursion is a good approach here.

Consider the following example code that prints an array. You basically have two cases:

1. The item passed does not have dependencies - print the item
2. The item passed has references - for each reference, handle it by recursing, then print the item itself

In rough code, this would look like the following:

sub print_item_dependencies( $item ) {
    for my $dep (@{$item->{dependencies}}) {
        print_item_dependencies( $dep );
    }
    say join "/", $item->{tool}, $item->{version}
}
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