sub my_uc {
    my $c = shift;
    return uc($c);
}

my @a = ('a'..'c');

@a = map { uc($_) } @a;
print "==>@a<== { uc(\$_) }\n";

@a = map { my_uc($_) } @a;
print "==>@a<== { my_uc(\$_) }\n";

@a = map uc, @a;
print "==>@a<== uc,\n";

@a = map my_uc, @a;
print "==>@a<== my_uc,\n";

##</code><code>##

==>A B C<== { uc($_) }
==>A B C<== { my_uc($_) }
==>A B C<== uc,
==>  <== my_uc,

##</code><code>##

sub my_new_uc {
    my $c = shift // $_;
    return uc($c);
}

sub my_uc {
    my $c = shift;
    return uc($c);
}

my @a = ('a'..'c');

@a = map my_new_uc, @a;
print "==>@a<== my_new_uc,\n";

@a = map my_uc, @a;
print "==>@a<== my_uc,\n";

@a = map my_new_uc, @a;
print "==>@a<== my_new_uc,\n";

##</code><code>##

==>A B C<== my_new_uc,
==>  <== my_uc,
==>  <== my_new_uc,