The Elixir community uses the free version of Slack; the problem is that with the free version only the most recent 10,000 messages are accessible, and the Elixir community generates that many messages in only a few days.

For the past couple of months, I've been programming in V. Their community uses Discord, which doesn't appear to have the same limitation re number of messages. Discord is not quite as nice to use as Slack, but that's a small price to pay for being able to access older messages.

Both discord and slack can be used satisfactorily in web browsers, and they both have free apps for both mobile devices and desktops/laptops. 

Thoughts re textmate:

I've been a happy textmate user for years, but since starting programming in V, I've paid for a subscription to Sublime Text because they have a V bundle (or at least have a port of the Visual Studio bundle for V). But I much prefer Textmate as an editor! And it would be great if someone could port a V bundle to. Textmate, or provide an easy way for Textmate to import Sublime Text or Visual Studio bundles.