> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/perl6-rosettacode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/perl6-rosettacode/programming_tasks/s/singly-linked-list/element_definition.md).

# Element definition

#### With `Pair`

A `Pair` (constructed with the `=>` operator) can be treated as a cons cell, and thus used to build a linked lists:

```perl
my $elem = 42 => $nextelem;
```

However, because this is not the primary purpose of the `Pair` type, it suffers from the following limitations:

#### With custom type

For more flexibility, one would create a custom type:

```perl
class Cell {
    has      $.value is rw;
    has Cell $.next  is rw;
    
    # ...convenience methods here...
}

sub cons ($value, $next) { Cell.new(:$value, :$next) }

my $list = cons 10, (cons 20, (cons 30, Nil));
```