output.log

$ raku --version
Welcome to 𝐑𝐚𝐤𝐮𝐝𝐨™ v2021.06.
Implementing the 𝐑𝐚𝐤𝐮™ programming language v6.d.
Built on MoarVM version 2021.06.

$ raku attint.raku 
-> ;; $_? is raw = OUTER::<$_> { #`(Block|82273360) ... }
this is baz
-> ;; $_? is raw = OUTER::<$_> { #`(Block|82280920) ... }
this is bar
(Callable)
No such method 'CALL-ME' for invocant of type 'Callable'
  in method run at attint.raku line 16
  in block <unit> at attint.raku line 19

testfile.raku

#!/usr/bin/env raku
use v6;
class Foo {
   has &!foo = { put 'this is foo' };
   has &!bar;
   has &!baz;
   method BUILD (:&!foo, :&!bar = { put 'this is bar' }, :&!baz) {
      &!baz //= { put 'this is baz' }
   }
   method run {
      &!baz.say;
      &!baz();
      &!bar.say;
      &!bar();
      &!foo.say;
      &!foo();
   }
}
Foo.new.run;