In Perl, putting an array into a scalar variable gives you its length. In Raku, the scalar holds the whole array.
Perl programmers count an array by putting it into a scalar. Raku keeps the array.
In Perl
my @cities = ("Riga", "Leiden", "Turin");
my $n = @cities;
print "$n\n";
print "There are $n cities\n";3 There are 3 cities
In Raku
my @cities = 'Riga', 'Leiden', 'Turin'; my $n = @cities; say $n; say "There are $n cities";
[Riga Leiden Turin] There are Riga Leiden Turin cities
There is no error. The program runs and prints a sentence you did not want.
Why
Perl decides what an array gives you from the place where you use it: put it where one value is expected, and you get the count. Raku does not work that way. A $ variable holds one thing, and that one thing can be a whole array.
It is the same array, not a copy. Add a city to @cities, and $n sees it:
my @cities = 'Riga', 'Leiden', 'Turin';
my $n = @cities;
@cities.push('Ghent');
say $n;
say $n.WHAT;
[Riga Leiden Turin Ghent] (Array)
Say it in Raku
Ask for the count with .elems:
my @cities = 'Riga', 'Leiden', 'Turin'; my $n = @cities.elems; say $n; say "There are $n cities";
3 There are 3 cities
Where Raku does expect a number, an array gives its count. A + in front of it asks for a number, and so does a numeric comparison:
my @cities = 'Riga', 'Leiden', 'Turin';
say "There are {+@cities} cities";
say 'More than two' if @cities > 2;
There are 3 cities More than two