Re: how to write a modified return() call?

[moritz]

That might be a bit overkill for your situation, but you could solve your problem with continuation passing, something along these lines:

sub resolve_value {
   my $start_with = another_value();
   unless $start_with {
        warn "Could not get another value";
        return;
   }
   my $continuation = shift;
   return $continuation->($start_with, @_);
}

# and here's how you use that code:

sub foo {
    # do some work here
    resolve_value(sub {
       my $start_with = shift;
       
       # do the rest of the work here
    })
}

If you care about performance you could also tail-call into the sub:

goto &resolve_value(sub {
    ...
});

[j1n3l0]

I think you've been spending too much time in Rakudo moritz ;)

unless $start_with { ... } # missing "()" around $start_with