Analyses the an array of META6.json-ish hashes to determine the required build order and also provides a control mechanism for building as efficiently as possible.

Really only needs an array of { :name, :depends([]) } of all of the dependencies required

Returns a Channel you can use for flow control for whatever you're doing.

Example:

my %tree = depends-tree(@list-of-metas);
my $flow = depends-channel(%tree);

loop {
  if $flow.poll -> $key {
    # do something with %tree{$k}
    %tree{$k}<promise>.keep; # this is important so the controller
                             # knows it can send the next item to be
                             # built
  }
  if $flow.closed { last }
  sleep .5;
};

Check out t/build-order.t:32 for a more complex example.

Returns a very simply graphviz dot format string that you can use to write to a file and generate a chart.

Will die if $force ~~ False or if which dot does not return the path to graphviz's dot.

This method attempts to generate the dot file, runs dot -T png -o <tmp-file.png> <tmp-file.dot> and returns the string path to the png file.