speculative diagram DSL syntax

class Page {
    has Str $.style = 'fill: #333333';

class Book {
    has Str $.abbreviation;
    has Str $.name;
    has Str $.author;
    has Str $.year;
    has Page @.pages;
}

diagram BookLayouts {
    element LAYOUT { <booktable> on <attribution> }

    element booktable { table(<book> from .books, :4columns) }

    element book { .abbreviation on table(<page> from .pages, :10columns) }

    element page { <rect width="1" height="2" style="{.style}"> }

    element attribution {
        vline on "SOURCE BOOKS"
              on table(<source> from .books, :2columns, :down)
    }

    element source { .name on "by $_.author, $_.year" }
}

my Book @books = ...;
BookLayouts.render(:@books);