Table of contents
Mailing Lists and Web Forums
Mailing lists and other forums used to discuss OCaml in general are listed below. There are thousands of other forums related to individual projects. Several mailing lists are hosted on the lists.ocaml.org domain. Projects on GitHub actively use GitHub's Issue system for discussions.
Discuss at OCaml.org
discuss.ocaml.org This is the most active forum about OCaml. Topics are grouped into a variety of categories, which can be followed independently. This forum welcomes people at all levels of proficiency, including beginners. A mailing-list mode is also available for those who wish to receive all messages.
Most categories are in English but categories in other languages are welcome.
Official OCaml List
caml-list AT inria.fr The OCaml mailing list is intended for all users of the OCaml implementations developed at Inria. The purpose of this list is to share experience, exchange ideas and code, and report on applications of the OCaml language. This list is not moderated, but posting is restricted to the subscribers of the list. Messages are generally in English but sometimes also in French. In 2010, the list has about 1500 subscribers, who exchange about 300 messages per month.
The OCaml Weekly News also provides a curated summary of caml-list discussions.
OCaml Jobs and Internships
ocaml-jobs AT inria.fr This list is for exchanges between people looking for a job or an internship requiring skills in OCaml and people, corporations, universities, ..., offering such jobs or internships.
caml-announce AT inria.fr This is a low-traffic, moderated list for announcements of OCaml releases and new OCaml-related software, libraries, documents, etc.
IRC Channel - English
irc.freenode.net #ocaml This is a real-time communication channel, where you can ask for help. There are about a hundred users hanging around; don't ask if you can ask, just ask, and be patient: not everyone is in the same timezone. The IRC Channel can be accessed through a web interface or any regular IRC client.
Public channel logs are available at http://irclog.whitequark.org/ocaml/
If you wish to use a web-based IRC client, you can use Freenode's webchat https://webchat.freenode.net/. For a fancier/nicer interface, you may try https://vector.im/beta/#/room/#freenode_#ocaml:matrix.org -- it requires registration but is otherwise free.
discord link: As a more recent addition to the OCaml community, the OCaml discord server benefits from the proximity of the ReasonML community's discord server, as well as discord's ability to have multiple channels. One of the channels is called #IRC, and automatically connects to the main IRC channel.
IRC Channel - French
irc.freenode.net #ocaml-fr As above, but for French speakers.
comp.lang.ml This is a moderated Usenet newsgroup about all variants of ML. Discussions generally concern Standard ML implementations (such as SML-NJ), but some threads concern the OCaml branch.
About Functional Languages
comp.lang.functional This is an unmoderated usenet newsgroup for the discussion of all aspects of functional programming languages, including their design, application, theoretical foundation, and implementation. Discussions concern all families of functional programming languages including non-strict ones (e.g. Haskell) and strict ones (e.g. Scheme, SML or OCaml).
Mantis Bug Tracker
Inria manages the official distribution of OCaml and uses Mantis to track bugs and feature requests.