edit: I should have read further. The more interesting parts happen very late in the article. A lot of what is described is still possible (including the queryi

edit: I should have read further. The more interesting parts happen very late in the article. A lot of what is described is still possible (including the querying) in C#, but other things only in very awkward ways. Original post follows: It seems this is almost possible in C#. Missing is the required property proposal [0], so currently the choice is between having everything be optional, or using explicit constructors (which loses most of what is wanted here). But that does not seem like a huge difference: Member m = new() { FirstName = "Kelly", Books = new() { new() { Author = "Hohlbein, Wolfgang" }, new() { Author = "Tchaikovsky, Adrian" } } }; Definitions: public record struct Book { public string Author { get; set; } } public record struct Member { public string FirstName { get; set; } public List<Book> Books { get; set; } } [0]: https://github.com/dotnet/csharplang/issues/3630 https://github.com/dotnet/csharplang/issues/3630