type t =
  | Lib
  | Lib_root
  | Libexec
  | Libexec_root
  | Bin
  | Sbin
  | Toplevel
  | Share
  | Share_root
  | Etc
  | Doc
  | Stublibs
  | Man
  | Misc

let all =
  [ Lib, "lib"
  ; Lib_root, "lib_root"
  ; Libexec, "libexec"
  ; Libexec_root, "libexec_root"
  ; Bin, "bin"
  ; Sbin, "sbin"
  ; Toplevel, "toplevel"
  ; Share, "share"
  ; Share_root, "share_root"
  ; Etc, "etc"
  ; Doc, "doc"
  ; Stublibs, "stublibs"
  ; Man, "man"
  ; Misc, "misc"
  ]
;;

let to_string t = List.assoc t all

let rec of_string x = function
  | [] -> None
  | (s, x') :: xs -> if x' = x then Some s else of_string x xs
;;

let of_string x = of_string x all