Nested Lookup

Nested references let a program group related values inside larger data structures.
nested data Nested data stores one structure inside another structure.
                            user
                            user = "ana" (default)user = "ben"user = "cy"
                        

                            nested_lookup.pl
                        
Replay: real traced execution (multi-file project)

                            use strict;
use warnings;

my $user = "ana";
my $profiles = {
    ana => { city => "Oslo", points => 4 },
    ben => { city => "Lima", points => 7 },
};
my $profile = $profiles->{$user};
my $city = $profile ? $profile->{city} : "none";
my $points = $profile ? $profile->{points} : 0;

print "user=$user\n";
print "city=$city\n";
print "points=$points\n";
use strict;
use warnings;

my $user = "ben";
my $profiles = {
    ana => { city => "Oslo", points => 4 },
    ben => { city => "Lima", points => 7 },
};
my $profile = $profiles->{$user};
my $city = $profile ? $profile->{city} : "none";
my $points = $profile ? $profile->{points} : 0;

print "user=$user\n";
print "city=$city\n";
print "points=$points\n";
use strict;
use warnings;

my $user = "cy";
my $profiles = {
    ana => { city => "Oslo", points => 4 },
    ben => { city => "Lima", points => 7 },
};
my $profile = $profiles->{$user};
my $city = $profile ? $profile->{city} : "none";
my $points = $profile ? $profile->{points} : 0;

print "user=$user\n";
print "city=$city\n";
print "points=$points\n";

                        
1$user ← ana, $city ← Oslo, $points ← 4⋯4my $user→ ana = "ana"; #@user="ben", "cy"5my $profiles = {6    ana => { city => "Oslo", points => 4 },7    ben => { city => "Lima", points => 7 },8};9my $profile = $profiles->{$user};10my $city→ Oslo = $profile ? $profile->{city} : "none";11my $points→ 4 = $profile ? $profile->{points} : 0;1213print "user=$userana\n";14print "city=$cityOslo\n";15print "points=$points4\n";⋯outputuser=ana
city=Oslo
points=4
1$user ← ben, $city ← Lima, $points ← 7⋯4my $user→ ben = "ben";5my $profiles = {6    ana => { city => "Oslo", points => 4 },7    ben => { city => "Lima", points => 7 },8};9my $profile = $profiles->{$user};10my $city→ Lima = $profile ? $profile->{city} : "none";11my $points→ 7 = $profile ? $profile->{points} : 0;1213print "user=$userben\n";14print "city=$cityLima\n";15print "points=$points7\n";⋯outputuser=ben
city=Lima
points=7
1$user ← cy, $profile ← (empty), $city ← none, $points ← 0⋯4my $user→ cy = "cy";5my $profiles = {6    ana => { city => "Oslo", points => 4 },7    ben => { city => "Lima", points => 7 },8};9my $profile→ (empty) = $profiles->{$user};10my $city→ none = $profile(empty) ? $profile->{city} : "none";11my $points→ 0 = $profile(empty) ? $profile->{points} : 0;1213print "user=$usercy\n";14print "city=$citynone\n";15print "points=$points0\n";⋯outputuser=cy
city=none
points=0