con not find symbol &gourp, but sub group is export(:MANDATORY) { ...}

add.pm6

#---add.pm----
unit module add;
use Term::Choose;
use Prompt::Gruff::Export;
use check; 
use datas;

########  PRIVATE FUNCTIONS  ##################################################################

sub ask_add_new {
  return prompt-for("Would you like to add an other one new repo ?", :yn(1));
}

my sub ask_repo_datas {
  my ($title, $url);
  $title= prompt-for( "Give a title for the new repo to add: " );
  $url= prompt-for( "give me the repo url: ", :regex("^https://") );
  return ($title, $url);
}

sub change_repo_datas(Str $title, Str $url){
  $title = change_title( $title );
  $url = change_url( $url );
  return ($title, $url);
}

sub change_title(Str $title){
  return prompt-for( "Change the title \"$title\" : " );
}

sub change_url(Str $url) {
  return prompt-for( "Change the url \"$url\" : ", :regex("^https://") );
}

########  PUBLIC FUNCTIONS  ###################################################################
# _Menu answer a) I want to add repos group
our sub group($yaml) is export(:MANDATORY) {
  my $group_name;
  while (1) {
    $group_name= prompt-for( "Which name to give for this new group ?", :yn(1) ); 
    if ( ! check.group_exist($yaml, $group_name) ) {
      if ($group_name eq "") {
        say "exit... "; 
        return 0;
      } else {
        $yaml.add_group( $group_name );
        $yaml.save();
        return;
      }
    } else { say "\ngroup exist allready... choose an other one name please."; }
  }
  return;
}

# _Menu answer b) i want to add repos
our sub repos($yaml) is export(:MANDATORY) {
  my ( @group_list, $group_name, $title, $url );
  my $add_repo= 1;
  $yaml.datas.map: { @group_list.push: $_<group>; };
  until ( defined $group_name ) {
    $group_name= choose( @group_list, 
        :prompt("which group for add repos inside ? choose..."),
        :index(1), :mouse(1), :layout(2) );
  }
  while ( $add_repo ) { 
    my $correct = 0 ;
    ($title, $url) = ask_repo_datas();
    until ( $correct ) {
      my $answer = check.repo_is_correct( $yaml, $group_name, $title, $url );
      given "$answer" {
        when "title exist" { say "title exist allreay in the database"; 
                             $title = change_title( $title ); }
        when "url exist" { say "url exist allready in the database"; 
                           $url = change_url( $url ); }
        when "want to change" { ( $title, $url ) = change_repo_datas( $title, $url );  }
        when "remote repo failed" { say "remote repo does not exist or is down"; 
                                    $url = change_url( $url ); }
        when "all is ok" { 
          $yaml.add_repo( $group_name, $title, $url );
          $yaml.save(); 
          $correct = 1;
        }
      }
    }
    $add_repo = ask_add_new();
  }
  return;
}

datas.pl6

#--datas.pm---

use YAML;

class datas {
  has Str $.filename is rw;
  has Array @.datas;
  has Str $!directory= %*ENV<HOME> ~ "/.vim/installer";;
  has Str $!repo_dir= %*ENV<HOME> ~ "/.vim/bundle";
  has Str $!full_filename= $!directory ~ "/$!filename";
  method new (Str $filename) {
    return self.bless: filename => $filename;
  }

  method TWEAK {
    self.initialize_directory();
    self.initialize_filename_data();
    my $thing = slurp $!full_filename;
    # self.datas = load($thing);
  }

  method initialize_directory() {
    unless $!directory.IO.d  { mkdir $!directory or die "unable to create directory"; }
  }

  method initialize_filename_data() {
    unless $!full_filename.IO.f  { 
      my @default = [ { group => "default", repos => [ { url => "", title => "" } ] } ];
      spurt $!full_filename, dump( @default );
    } 
  }
  
  method save {
    spurt $!full_filename, dump(@!datas) or die "can not save datas.yml";
    say "Datas has been saved.";
  }

  method add_group( $group_name ){
    @!datas.push: { group => "$group_name", repos => [] };
  }

  has method add_repo($group_name, $title, $url) {
    @!datas.map: {
      if ( $_<group> eq $group_name ) {
        $_<repos>.push: { title => "$title", url => "$url"}; }
    }
  }
}

my_pl6.yml

---
- !Pair
  key: repos
  value:
  - !Pair
      key: title
      value: 
  - !Pair
      key: url
      value: 
- !Pair
  key: group
  value: default
...

VimPlugger.pl6

#!/usr/bin/perl6
#use install;
use lib "/home/jerome/PROGRAMATION/Perl/Vim_plugger_6/";
use Term::Choose;
use datas;
use add :MANDATORY;

my $mode;
my $yaml = datas.new("my_pl6.yml");
my @menu0 = < List Add Modify Remove Install Uninstall Update Quit >;
my @menu_List = ( "Liste repos of group", 
                  "Liste all the repos of database", 
                  "List all installed repos" );
my @menu_Add = ( "Add new group", "Add new repos to group" );
my @menu_Remove = ( "Remove group", "Remove repos from group" );
my @menu_Modify = ( "Modify name of group", "Mofify repos" );
my @menu_Install = ( "Install repos from group", "Install all repos" );
my @menu_Uninstall = ( "Unisnstall repos from group", "Uninstall all repos" );
# Questions: what to do ?
sub menu($title, @list) {
   my $title_ex = "\nWhat do you want to do ?\n $title";
    $mode = choose( @list, :index(0), :layout(2), :mouse(1), :prompt($title_ex) );
  return $mode;
}

while ( $mode = menu("Choose:", @menu0) ) {
  given $mode {
    when "List" { 
      my $action = menu("Print a list: ", @menu_List);
      given $action {
        when "List all the repos of database" {  }
        when "List repos of group" {  }
        when "List all installed repos" {  } } }
    when "Add" {
      my $action = menu("Add something: ", @menu_Add);
      given $action {
        when "Add new group" { add::group($yaml); } 
        when "Add new repos to group" { add::repos($yaml); }
      }
    }
    when "Modify" {
      my $action = menu("Modification :", @menu_Modify);
      given $action {
        when "Modify a repos" {  }
        when "Modify name of group" {  } } }
    when "Remove" {
      my $action = menu("Remove:", @menu_Remove);
      given $action {
        when "Remove repos from a group" {  }
        when "Remove group" {  } } }
    when "Install" {
      my $action = menu("Install for vim", @menu_Install);
      given $action {
        when "Install repos from group" { } #install::repos_from_group($yaml); }
        when "Install all repos" {  } } }
    when "Uninstall" {
      my $action = menu("Uninstall repos:", @menu_Uninstall);
      given $action {
        when "Uninstall repos from group" {  }
        when "Uninstall all repos" {  } } }
    when "Update" {  } 
    when "Quit" { exit; }
  }
}

the yaml file syntax is wrong, it should have an Array content Hashes.
Instead, it contains an Array with two Hashes.
why ?