Course of Raku / Advanced / More about built-in types / Native types 🆕

Machine-level types

The native types have lower-case names: int, num, and str. You declare a variable with one of them just as you would with Int or Str:

my int $i = 42;
my num $n = 3.14e0;
say $i; # 42
say $n; # 3.14

A native value corresponds directly to a machine register or word, without the wrapper object that a normal Raku value carries. This makes native types faster and more compact, which matters in tight numeric loops and large arrays.

There is one behaviour to be aware of straight away: a native variable can never be undefined. Where an ordinary Int container starts as the undefined Any, a native int starts at zero:

say (my Int $a); # (Int)
say (my int $b); # 0

The same applies to native arrays, declared by putting the native type before the @ variable:

my int @numbers = 10, 20, 30;
say @numbers.sum; # 60

Such an array stores its elements as raw machine integers rather than as boxed Int objects, so it uses less memory. When you introspect a native value it is automatically boxed into the matching full type, which is why (my int $b).WHAT reports (Int).

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