anil.recoil.org
OCaml Claude SDK using Eio and Jsont
1(*---------------------------------------------------------------------------
2 Copyright (c) 2025 Anil Madhavapeddy <anil@recoil.org>. All rights reserved.
3 SPDX-License-Identifier: ISC
4 ---------------------------------------------------------------------------*)
5
6(* Simple example showing structured output with explicit JSON Schema *)
7
8module C = Claude
9
10let () =
11 Logs.set_reporter (Logs_fmt.reporter ());
12 Logs.set_level (Some Logs.Info)
13
14let simple_example env =
15 Printf.printf "\n=== Simple Structured Output Example ===\n\n";
16
17 (* Define a simple schema for a person's info *)
18 let person_schema =
19 let open Jsont in
20 Object
21 ( [
22 (("type", Meta.none), String ("object", Meta.none));
23 ( ("properties", Meta.none),
24 Object
25 ( [
26 ( ("name", Meta.none),
27 Object
28 ( [ (("type", Meta.none), String ("string", Meta.none)) ],
29 Meta.none ) );
30 ( ("age", Meta.none),
31 Object
32 ( [ (("type", Meta.none), String ("integer", Meta.none)) ],
33 Meta.none ) );
34 ( ("occupation", Meta.none),
35 Object
36 ( [ (("type", Meta.none), String ("string", Meta.none)) ],
37 Meta.none ) );
38 ],
39 Meta.none ) );
40 ( ("required", Meta.none),
41 Array
42 ( [
43 String ("name", Meta.none);
44 String ("age", Meta.none);
45 String ("occupation", Meta.none);
46 ],
47 Meta.none ) );
48 ],
49 Meta.none )
50 in
51
52 let output_format =
53 Claude.Proto.Structured_output.of_json_schema person_schema
54 in
55
56 let options =
57 C.Options.default
58 |> C.Options.with_output_format output_format
59 |> C.Options.with_max_turns 1
60 in
61
62 Printf.printf "Asking Claude to provide structured data...\n\n";
63
64 Eio.Switch.run @@ fun sw ->
65 let process_mgr = Eio.Stdenv.process_mgr env in
66 let clock = Eio.Stdenv.clock env in
67 let client = C.Client.create ~sw ~process_mgr ~clock ~options () in
68
69 C.Client.query client
70 "Tell me about a famous computer scientist. Provide their name, age, and \
71 occupation in the exact JSON structure I specified.";
72
73 let responses = C.Client.receive_all client in
74 List.iter
75 (function
76 | C.Response.Complete result -> (
77 Printf.printf "Response received!\n";
78 match C.Response.Complete.structured_output result with
79 | Some json ->
80 Printf.printf "\nStructured Output:\n%s\n"
81 (Test_json_utils.to_string ~minify:false json)
82 | None -> Printf.printf "No structured output\n")
83 | C.Response.Error err ->
84 Printf.printf "Error: %s\n" (C.Response.Error.message err)
85 | _ -> ())
86 responses
87
88let () =
89 Eio_main.run @@ fun env ->
90 try simple_example env
91 with exn ->
92 Printf.eprintf "Error: %s\n" (Printexc.to_string exn);
93 exit 1