Estou tentando escrever um código executável simples em OCaml abaixo.
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 )
Mas continuo vendo o seguinte quando executo 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
Em outras postagens do StackOverflow, parece estar relacionado aos diferentes tipos retornados no , if/elsemas me certifiquei de que todos eles if/elseestão usando printf.
Eu agradeceria se alguém pudesse me dizer o que mais estou fazendo errado.
