open Logarion
let authors r topics_opt =
	let predicates = Archive.(predicate topics topics_opt) in
	let predicate text = List.fold_left (fun a e -> a && e text) true predicates in
	let author_union a (e, _) = Person.Set.union a e.Text.authors in
	let s = File_store.fold ~r ~predicate author_union Person.Set.empty in
	Person.Set.iter (fun x -> print_endline (Person.to_string x)) s

open Cmdliner
let term =
	let recurse = Arg.(value & flag & info ["R"]
		~doc:"include texts in subdirectories too") in
	let topics = Arg.(value & opt (some string) None & info ["topics"]
		~docv:"TOPICS" ~doc:"display authors who have written on topics") in
	Term.(const authors $ recurse $ topics),
	Term.info "authors" ~doc:"list authors"
		~man:[ `S "DESCRIPTION"; `P "List author names" ]