Course of Raku / Advanced / Containers / Scalar containers

Data types and scalar containers

Let us look at a program that reuses the same variable to hold different kinds of data. We use dd to see what the container holds at each step. This example is here for demonstration purposes and is not a recommended programming style.

my $value;
dd $value;

$value = 42;
dd $value;

$value = 'forty-two';
dd $value;

Each dd call shows what the $value variable currently contains:

$value = Any
$value = 42
$value = "forty-two"

At first, the variable is empty, and dd reports its value as Any — the undefined base value that an untyped container starts with. After the assignments, dd shows the integer and then the string.

Notice that dd does not print a type before the name here. An untyped container does not commit to any type, so only the value is shown. As you will see in the next topic, a container with a declared type behaves differently.

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