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let bigint_to_yojson (num : Bigint.t) : Yojson.Safe.t =
`String (Bigint.to_string num)
let bigint_of_yojson : Yojson.Safe.t -> (Bigint.t, string) result = function
| `String n -> (
try Ok (Bigint.of_string n)
with _ -> Error (Format.sprintf "error while converting %s to Bigint" n))
| `Int n -> Ok (Bigint.of_int n)
| json ->
Error (Format.sprintf "invalid Bigint: %s" (Yojson.Safe.to_string json))
let array_to_yojson (e_to_yojson : 'a -> Yojson.Safe.t) (arr : 'a Array.t) :
Yojson.Safe.t =
`List (Array.to_list (Array.map e_to_yojson arr))
let array_of_yojson (e_of_yojson : Yojson.Safe.t -> ('a, string) result)
(json : Yojson.Safe.t) : ('a Array.t, string) result =
match json with
| `List lst ->
let rec aux acc = function
| [] -> Ok (Array.of_list (List.rev acc))
| x :: xs -> (
match e_of_yojson x with
| Ok v -> aux (v :: acc) xs
| Error e -> Error e)
in
aux [] lst
| _ -> Error "expected a JSON list"
module Map = struct
module Make (V : sig
type t [@@deriving yojson]
end) =
struct
module M = Map.Make (Int)
include M
type t = V.t M.t
let to_yojson (t : t) : Yojson.Safe.t =
let kvs =
bindings t |> List.map (fun (k, v) -> (string_of_int k, V.to_yojson v))
in
`Assoc kvs
let of_yojson (j : Yojson.Safe.t) : (t, string) result =
match j with
| `Assoc kvs ->
let rec aux acc = function
| [] -> Ok acc
| (ks, vj) :: tl -> (
match int_of_string_opt ks with
| None -> Error ("Key is not an int: " ^ ks)
| Some k -> (
match V.of_yojson vj with
| Error e -> Error ("Value error at key " ^ ks ^ ": " ^ e)
| Ok v -> aux (M.add k v acc) tl))
in
aux M.empty kvs
| _ -> Error "Expected JSON object"
end
end