Your wish is my command...

use v5.14;

package Foo {
   use Moo;
   use MooseX::MungeHas 0.007 { hasro => ["is_ro"], hasrw => ["is_rw"]
+ };
   
   hasro "foo";
   hasrw "bar" => sub { "this is a very lazy builder" };
}

my $f = Foo->new(foo => 1);
say $f->foo;  # "1"
say $f->bar;  # "this is a very lazy builder"
$f->bar(2);   # it's an rw attribute
say $f->bar;  # "2"
$f->foo(2);   # it's an ro attribute, dies
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