add amount.mli

src/amount.ml

@@ -1,7 +1,7 @@
 (* TODO
      have safe amount arithmetic
      make type private
-     use config currency option *)
+     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
@@ -11,9 +11,13 @@
 
      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: [ `Plus | `Minus ] option;
-  currency: [ `Eur ];
+  sign: sign option;
+  currency: string;
   value: Int64.t;
   fraction: Int32.t;
 }
@@ -37,11 +41,12 @@ let make ~sign ~currency ~value ~fraction =
 
 let pp =
   let open Fmt in
-  let pp_sign ppf = function `Plus -> char ppf '+' | `Minus -> char ppf '-' in
-  let pp_currency ppf = function `Eur -> string ppf "EUR" in
+  let pp_sign ppf = function
+    | Sign_plus -> char ppf '+'
+    | Sign_minus -> char ppf '-'
+  in
   fun ppf { sign; currency; value; fraction } ->
-    pf ppf "%a%a:%Ld.%02ld" (Fmt.option pp_sign) sign pp_currency currency value
-      fraction
+    pf ppf "%a%s:%Ld.%02ld" (Fmt.option pp_sign) sign currency value fraction
 
 let to_string = Fmt.str "%a" pp
 
@@ -50,11 +55,16 @@ let of_string =
   let parse_sign =
     choice
       [
-        char '+' *> return (Some `Plus); char '-' *> return (Some `Minus);
-        return None;
+        char '+' *> return (Some Sign_plus);
+        char '-' *> return (Some Sign_minus); return None;
       ]
   in
-  let parse_currency = string "EUR" *> return `Eur 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

src/amount.mli

@@ -0,0 +1,21 @@
+type sign =
+  | Sign_plus
+  | Sign_minus
+
+type t = private {
+  sign: sign option;
+  currency: string;
+  value: Int64.t;
+  fraction: Int32.t;
+}
+
+val make :
+  sign:sign option ->
+  currency:string ->
+  value:Int64.t ->
+  fraction:Int32.t ->
+  (t, string) result
+
+val pp : Format.formatter -> t -> unit
+val to_string : t -> string
+val of_string : string -> (t, string) result

src/config.ml

@@ -206,3 +206,6 @@ module Exchange_secmod_eddsa = struct
   let lookahead_sign = get "lookahead_sign" |> duration
   let overlap_duration = get "overlap_duration" |> duration
 end
+
+(* -- *)
+include Exchange

src/pg.ml

@@ -17,7 +17,7 @@ let pg_amount : Amount.t Caqti_type.t =
   Caqti_type.custom
     ~encode:(fun amount -> Ok (amount.value, amount.fraction))
     ~decode:(fun (value, fraction) ->
-      Ok { sign= None; currency= `Eur; value; fraction })
+      Amount.make ~sign:None ~currency:Config.currency ~value ~fraction)
     Caqti_type.(t2 int64 int32)
 
 (* WIP: minimum db functions for basic /management *)

test/test.ml

@@ -30,12 +30,9 @@ let () =
 let () =
   let open Types.Amount in
   let v =
-    {
-      sign= Some `Plus;
-      currency= `Eur;
-      value= Int64.of_int 25;
-      fraction= Int32.of_int 678;
-    }
+    Amount.make ~sign:(Some Amount.Sign_plus) ~currency:"EUR"
+      ~value:(Int64.of_int 25) ~fraction:(Int32.of_int 678)
+    |> Result.get_ok
   in
   let s = to_string v in
   let v' = of_string s |> Result.get_ok in