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Martin Hope
Vlam
Asked: 2025-01-09 13:49:16 +0800 CST
  • 5

我正在尝试用下面的 OCaml 编写一个简单的可执行代码。

open Printf
open Lwt
open Cohttp
open Cohttp_lwt_unix
open Yojson

let () =
  let ip = "8.8.8.8" in
  let key = "" in
  let uri =
    Uri.of_string
      ("https://api.ip2location.io/?format=json&key=" ^ key ^ "&ip=" ^ ip)
  in
  Lwt_main.run
    ( Client.get uri >>= fun (resp, body) ->
      let code = resp |> Response.status |> Code.code_of_status in
      let json_promise = body |> Cohttp_lwt.Body.to_string in
      json_promise >>= fun json_string ->
      let json = Basic.from_string json_string in
      let open Yojson.Basic.Util in
      if code == 200 then
        if member "usage_type" json <> `Null then
          let usage_type = json |> member "usage_type" |> to_string in
          printf "usage_type: %s\n" usage_type
        else
          printf
            "ERROR: The usage_type field requires a paid subscription to the \
             Starter plan or higher."
      else if (code == 400 || code == 401) && member "error" json <> `Null then
        let error_message =
          json |> member "error" |> member "error_message" |> to_string
        in
        printf "ERROR: " ^ error_message
      else printf "HTTP Code: " ^ Int.to_string code )

但是当我跑步时我一直看到下面的内容dune build。

File "bin/main.ml", line 24, characters 10-46:
24 |           printf "usage_type: %s\n" usage_type
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This expression has type unit but an expression was expected of type
         'a Client.io

从其他 StackOverflow 帖子来看，它似乎与返回的不同类型有关，if/else但我已确保所有类型都if/else在使用printf。

如果有人能让我知道我还做错了什么，我将不胜感激。

ocaml
Martin Hope
Vlam
Asked: 2024-12-13 08:37:28 +0800 CST
  • 5

我正在为我的 OCaml 项目编写测试代码，当使用下面的代码时，它运行良好。

open Printf
open Ip2location

(* query IP2Location BIN datababase *)
let meta = Database.open_db "./IP2LOCATION-LITE-DB1.IPV6.BIN";;

let ip = "2a02:3037:0400:6fa2:459c:84b6:967d:69e0";;
let res = Database.query meta ip;;

printf "country_short: %s\n" res.country_short;;
printf "country_long: %s\n" res.country_long;;
printf "region: %s\n" res.region;;
printf "city: %s\n" res.city;;
printf "isp: %s\n" res.isp;;
printf "latitude: %f\n" res.latitude;;
printf "longitude: %f\n" res.longitude;;
printf "domain: %s\n" res.domain;;
printf "zip_code: %s\n" res.zip_code;;
printf "time_zone: %s\n" res.time_zone;;
printf "net_speed: %s\n" res.net_speed;;
printf "idd_code: %s\n" res.idd_code;;
printf "area_code: %s\n" res.area_code;;
printf "weather_station_code: %s\n" res.weather_station_code;;
printf "weather_station_name: %s\n" res.weather_station_name;;
printf "mcc: %s\n" res.mcc;;
printf "mnc: %s\n" res.mnc;;
printf "mobile_brand: %s\n" res.mobile_brand;;
printf "elevation: %f\n" res.elevation;;
printf "usage_type: %s\n" res.usage_type;;
printf "address_type: %s\n" res.address_type;;
printf "category: %s\n" res.category;;
printf "district: %s\n" res.district;;
printf "asn: %s\n" res.asn;;
printf "as: %s\n" res.asys;;

Database.close_db meta;;

然后，我修改了代码以查询 IP 地址列表，如下所示：

open Printf
open Ip2location

(* query IP2Location BIN datababase *)
let meta = Database.open_db "./IP2LOCATION-LITE-DB1.IPV6.BIN";;

let mylist = ["0.0.0.0"; "8.3.34.0"; "8.8.8.8"; "3.91.171.8"; "37.252.228.50"; "64.94.62.0"; "197.85.191.64"; "255.255.255.254"; "255.255.255.255"; "179.125.12.0"; "::"; "2001::"; "2001:0:4136:e378:8000:63bf:f7f7:f7f7"; "2001:0000:4136:e378:8000:63bf:f7fc:ddff"; "2002::"; "2002:808:808::"; "2002:0803:2200::0803:2200"; "2600:1F18:45B0:5B00:0000:0000:0000:0000"; "::FFFF:FFFF"; "::FFFF:3.91.171.8"; "::FFFF:8.3.34.0"; "::FFFF:64.94.62.0"; "::FFFF:C555:BF40"; "ffff:ffff:ffff:ffff:FFFF:FFFF:FFFF:FFFE"; "FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF"; "0:0:0:0:0:ffff:b37d:0c00"; "0.0.0.256"; "0.0.0"; "1"; "A"];;

let getloc ip =
    let res = Database.query meta ip in
    printf "country_short: %s\n" res.country_short;;
    printf "country_long: %s\n" res.country_long;;
    printf "region: %s\n" res.region;;
    printf "city: %s\n" res.city;;
    printf "isp: %s\n" res.isp;;
    printf "latitude: %f\n" res.latitude;;
    printf "longitude: %f\n" res.longitude;;
    printf "domain: %s\n" res.domain;;
    printf "zip_code: %s\n" res.zip_code;;
    printf "time_zone: %s\n" res.time_zone;;
    printf "net_speed: %s\n" res.net_speed;;
    printf "idd_code: %s\n" res.idd_code;;
    printf "area_code: %s\n" res.area_code;;
    printf "weather_station_code: %s\n" res.weather_station_code;;
    printf "weather_station_name: %s\n" res.weather_station_name;;
    printf "mcc: %s\n" res.mcc;;
    printf "mnc: %s\n" res.mnc;;
    printf "mobile_brand: %s\n" res.mobile_brand;;
    printf "elevation: %f\n" res.elevation;;
    printf "usage_type: %s\n" res.usage_type;;
    printf "address_type: %s\n" res.address_type;;
    printf "category: %s\n" res.category;;
    printf "district: %s\n" res.district;;
    printf "asn: %s\n" res.asn;;
    printf "as: %s\n" res.asys

List.iter getloc mylist;;

Database.close_db meta;;

当我运行时dune test，我得到以下信息：

File "test/ip2locationtest.ml", line 12, characters 29-32:
12 |    printf "country_long: %s\n" res.country_long;;
                                    ^^^
Error: Unbound value res
Hint: Did you mean ref?

我是 OCaml 的新手，所以我不知道我错过了什么。如果能指出我做错了什么，我将不胜感激。

ocaml