rename to lib/

src/amount.ml

@@ -1,90 +0,0 @@
-(* TODO
-     have safe amount arithmetic
-     make type private
-     redefine an Amount module with currency enforced to be Config.currency? *)
-(* Amounts of currency, serialized as `<Currency>:<IntegerPart>.<FractionalPart>`
-     Fixed-precision numbers with 8 decimal places.
-     - <Currency> must be at most 11 characters long
-       only consist of ASCII letters (a-zA-Z).
-     - integer part of <DecimalAmount> may be at most 2^52.
-     - fractional part of <DecimalAmount> may contain at most 8 decimal digits.
-
-     Prefixed with '+' or '-' in certain contexts.
-     When no sign is present, the amount is assumed to be positive. *)
-type sign =
-  | Sign_plus
-  | Sign_minus
-
-type t = {
-  sign: sign option;
-  currency: string;
-  value: Int64.t;
-  fraction: Int32.t;
-}
-
-let ( let* ) o f = match o with Ok v -> f v | Error _ as e -> e
-let check_not msg = function false -> Ok () | true -> Error msg
-let value_upper_bound = Z.(pow (of_int 2) 52) |> Z.to_int64
-let fraction_upper_bound = Int32.of_int 100_000_000
-
-let make ~sign ~currency ~value ~fraction =
-  let* () = check_not "value is negative" (value < Int64.zero) in
-  let* () = check_not "fraction is negative" (fraction < Int32.zero) in
-  let* () =
-    check_not "value is greater than 2^52" (value > value_upper_bound)
-  in
-  let* () =
-    check_not "fraction has more than 8 decimal digits"
-      (fraction >= fraction_upper_bound)
-  in
-  Ok { sign; currency; value; fraction }
-
-let pp =
-  let open Fmt in
-  let pp_sign ppf = function
-    | Sign_plus -> char ppf '+'
-    | Sign_minus -> char ppf '-'
-  in
-  fun ppf { sign; currency; value; fraction } ->
-    pf ppf "%a%s:%Ld.%02ld" (Fmt.option pp_sign) sign currency value fraction
-
-let to_string = Fmt.str "%a" pp
-
-let of_string =
-  let open Angstrom in
-  let parse_sign =
-    choice
-      [
-        char '+' *> return (Some Sign_plus);
-        char '-' *> return (Some Sign_minus); return None;
-      ]
-  in
-  let parse_currency =
-    (* TODO currency string constraint/format *)
-    take_while1 (function
-      | 'a' .. 'z' | 'A' .. 'Z' -> true
-      | _ -> false)
-  in
-  let parse_int64 =
-    take_while1 (function '0' .. '9' -> true | _ -> false)
-    >>| Int64.of_string_opt
-    >>= function
-    | None -> fail "invalid integer"
-    | Some n -> return n
-  in
-  let parse_int32 =
-    take_while1 (function '0' .. '9' -> true | _ -> false)
-    >>| Int32.of_string_opt
-    >>= function
-    | None -> fail "invalid integer"
-    | Some n -> return n
-  in
-  let parse_t =
-    lift4
-      (fun sign currency value fraction ->
-        make ~sign ~currency ~value ~fraction)
-      parse_sign parse_currency
-      (char ':' *> parse_int64)
-      (char '.' *> parse_int32)
-  in
-  fun s -> parse_string ~consume:Consume.All parse_t s |> Result.join