In F# you'd normally use a type provider for this kind of work, but for the sake of exercise: type Chapter = Map<int, string> type Book = Map<int, C

In F# you'd normally use a type provider for this kind of work, but for the sake of exercise: type Chapter = Map<int, string> type Book = Map<int, Chapter> type Bible = Map<string, Book> let bookOrder = [|"Genesis"; "Exodus"; "Leviticus"; (* etc.. *) |] let sortChapter = Map.toSeq >> Seq.sortBy fst >> Seq.toArray let sortBook = Map.map (fun _ -> sortChapter) >> Map.toSeq >> Seq.sortBy fst >> Seq.toArray let sortBible = Map.map (fun _ -> sortBook) >> Map.toSeq >> Seq.sortBy (fun (bookname, _)-> Array.findIndex ((=) bookname) bookOrder) >> Seq.toArray BIBLE_TEXT |> JsonConvert.DeserializeObject<Bible> |> sortBible |> printfn "%A" FP 101 suggests you could extract the Map.toSeq >> Seq.sortby x >> Seq.toArray function, but I don't think it gains any readability, and in any case it's just an artifact of the problem requiring an array output even though a Map would make more sense.