What is the best module for HttpRequest in OCaml - ocaml

Question

I wish to use OCaml to access the Yahoo Finance API. Essentially, it will be just a bunch of HTTP requests to get quotes from Yahoo Finance.
Which module I should use?
I wish to have async HTTP requests.

Answer 1

There are possibilities using lwt:
ocsigen has a quite complete and a bit complex implementation
cohttp is a bit simpler but lacks some usefull parts
using opam to install:
$ opam install ocsigenserver cohttp
For instance in a toplevel:
try Topdirs.dir_directory (Sys.getenv "OCAML_TOPLEVEL_PATH") with _ -> ();;
#use "topfind";;
#thread;;
#require "ocsigenserver";;
open Lwt
(* a simple function to access the content of the response *)
let content = function
| { Ocsigen_http_frame.frame_content = Some v } ->
Ocsigen_stream.string_of_stream 100000 (Ocsigen_stream.get v)
| _ -> return ""
(* launch both requests in parallel *)
let t = Lwt_list.map_p Ocsigen_http_client.get_url
[ "http://ocsigen.org/";
"http://stackoverflow.com/" ]
(* maps the result through the content function *)
let t2 = t >>= Lwt_list.map_p content
(* launch the event loop *)
let result = Lwt_main.run t2
and using cohttp:
try Topdirs.dir_directory (Sys.getenv "OCAML_TOPLEVEL_PATH") with _ -> ();;
#use "topfind";;
#require "cohttp.lwt";;
open Lwt
(* a simple function to access the content of the response *)
let content = function
| Some (_, body) -> Cohttp_lwt_unix.Body.string_of_body body
| _ -> return ""
(* launch both requests in parallel *)
let t = Lwt_list.map_p Cohttp_lwt_unix.Client.get
(List.map Uri.of_string
[ "http://example.org/";
"http://example2.org/" ])
(* maps the result through the content function *)
let t2 = t >>= Lwt_list.map_p content
(* launch the event loop *)
let v = Lwt_main.run t2
Notice that an implementation of cohttp for jane street async library is also available

Answer 2

Just for the record, there is also ocurl with curl multi API support.