Does Perl 6 have a built-in tool to make a deep copy of a nested data structure?

Question

Does Perl 6 have a built-in tool to make a deep copy of a nested data structure?

Added example:

my %hash_A = (
    a => {
        aa => [ 1, 2, 3, 4, 5 ],
        bb => { aaa => 1, bbb => 2 },
    },
);


my %hash_B = %hash_A;
#my %hash_B = %hash_A.clone; # same result

%hash_B<a><aa>[2] = 735;

say %hash_A<a><aa>[2]; # says "735" but would like get "3"

Answer 1

my %A = (
    a => {
        aa => [ 1, 2, 3, 4, 5 ],
        bb => { aaa => 1, bbb => 2 },
    },
);

my %B = %A.deepmap(-> $c is copy {$c}); # make sure we get a new container instead of cloning the value

dd %A;
dd %B;

%B<a><aa>[2] = 735;

dd %A;
dd %B;

Use .clone and .deepmap to request a copy/deep-copy of a data-structure. But don't bet on it. Any object can define its own .clone method and do whatever it wants with it. If you must mutate and therefore must clone, make sure you test your program with large datasets. Bad algorithms can render a program virtually useless in production use.

Answer 2

The dirty way:

#!/usr/local/bin/perl6

use v6;
use MONKEY-SEE-NO-EVAL;

my %hash_A = (
    a => {
        aa => [ 1, 2, 3, 4, 5 ],
        bb => { aaa => 1, bbb => 2 },
    },
);


my %hash_B;
EVAL '%hash_B = (' ~ %hash_A.perl ~ ' )';

%hash_B<a><aa>[2] = 735;

say %hash_A;
say %hash_B;

which gives you:

$ perl6 test.p6
{a => {aa => [1 2 3 4 5], bb => {aaa => 1, bbb => 2}}}
{a => {aa => [1 2 735 4 5], bb => {aaa => 1, bbb => 2}}}

If you eval input from external source, always remember to check it first. Anyway, using EVAL is dangerous and should be avoided.