There are several Perl 6 modules to provide one-way encryption of passwords.
I think Crypt::Bcrypt or Crypt::Argon2 would be the recommended ones to use, but currently they are both broken due to a dependency being broken. In the meantime, let's explore how the encryption could work using Crypt::Libcrypt.
push treats the supplied parameters as individual entities and pushes them onto the original array without flattening them.
append (introduced new after 2015.09 release) will flatten the supplied array - if there was only one array supplied, but will reat them as individual entities if more than one arrays are supplied.
Unless you want to actually develop Rakudo itself, the recommendation is to install the Rakudo Star package. It contains the Rakudo compiler, documentation, and some extra modules. It can automatically build MoarVM, so you don't need to worry about that.
Windows users are even more spoiled, as the Rakudo development team provides ready-made binaries of Rakudo Star in msi format.