smorimoto / ocaml-reddit-api

An OCaml wrapper to Reddit's API

reddit_api is a set OCaml client libraries for Reddit's API.

reddit_api_kernel provides:

• Types for representing Reddit's API parameters and responses
• Functions for building HTTP requests and handling the associated responses for Reddit's API endpoints.

reddit_api_async provides a client for sending these requests to Reddit and some utilities for common usage patterns. It handles authentication and Reddit's rate-limiting headers.

Documentation

Here. I recommend the Reddit_api_kernel.Endpoint and Reddit_api_async.Connection modules as entry points.

Example

let print_links credentials =
  let connection = Connection.create credentials ~user_agent:"Link printer" in
  let subreddit =
    Subreddit_name.combine (List.map ~f:Subreddit_name.of_string [ "ocaml"; "redditdev" ])
  in
  let%bind link_listing =
    Connection.call_exn connection (Endpoint.top ~since:Year ~subreddit ())
  in
  let links = Listing.children link_listing in
  List.iter links ~f:(fun link ->
      print_s
        [%sexp
          { title : string = Thing.Link.title link
          ; url : string option = Option.map (Thing.Link.url link) ~f:Uri.to_string
          ; author : Username.t option = Thing.Link.author link
          ; score : int = Thing.Link.score link
          }]);
  return ()

Goals and non-goals

Goals

• Provide a typed interface to Reddit's API endpoints and responses.
• Encode knowledge, documented or otherwise, about correct usage of the API via the type system.
  • Don't raise exceptions if Reddit is behaving "as expected."
  • Express corner cases in response types. For example, are there surprising cases where a field might not be present? Make the field optional instead of making each user discover this on their own.
  • Handle common Reddit server issues such as 503 errors automatically, or else warn about them via the response type.
• Provide workarounds when we get the above wrong:
  • The ability to directly edit the HTTP requests generated for each endpoint.
  • A Connection.call_raw function that allows users to access HTTP responses directly.

Non-goals

• Be perfect
  • Reddit's API is not very well documented. Determining which inputs and outputs are legal is largely a matter of trial and error. At any given time, it's likely that we allow some invalid combination of inputs, or forbid a valid combination, or fail to handle some valid response.
• Express "unexpected" Reddit behavior in the type system.
  • If we get something from Reddit that we don't understand, we'll just raise. We don't make every function return a (_, [`couldn't_parse_response]) Result.t).

Credits

Thanks to PRAW for providing innumerable examples of Reddit API client code.