imm: Execute arbitrary callbacks for each element of RSS/Atom feeds

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Dependencies aeson, async, atom-conduit (>=0.7), base-noprelude (>=4.7 && <5), binary, blaze-html, blaze-markup, bytestring, case-insensitive, conduit, connection, containers, dhall, directory (>=, fast-logger, filepath, hashable, HaskellNet (>=0.5), HaskellNet-SSL (>=, http-client (>=0.4.30), http-client-tls, http-types, imm, microlens, mime-mail, monad-time, msgpack, network (<3), opml-conduit (>=0.7), optparse-applicative, prettyprinter, prettyprinter-ansi-terminal, refined (>=0.4.1), relude, rss-conduit (>=0.4.1), safe-exceptions, stm, stm-chans, streaming-bytestring, streaming-with, text, time, timerep (>=, tls, typed-process, uri-bytestring, xml-conduit (>=1.5), xml-types [details]
License CC0-1.0
Author kamaradclimber, koral
Category Web
Home page
Source repo head: git clone git://
Uploaded by koral at Thu Jun 20 09:26:01 UTC 2019
Distributions NixOS:
Executables imm-sendmail, imm-writefile, imm
Downloads 9691 total (471 in the last 30 days)
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2019-06-20 [all 1 reports]


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imm is a program that executes arbitrary callbacks (e.g. sending a mail, or writing a file) for each element of RSS/Atom feeds.

imm is written in Haskell, configured in Dhall. The project includes:

  • a main executable imm that users directly run
  • additional executables (imm-writefile and imm-sendmail) that imm can be configured to use as callbacks
  • a Haskell library, that exports functions useful to both the main executable and callbacks; the API is documented in Hackage.


Callbacks are configured through the $XDG_CONFIG_HOME/imm/callbacks.dhall file. A commented template file is bundled with the project.

imm will call each callback once per feed element, and will fill its standard input (stdin) with a MessagePack-encoded object structured as follows:

  "feed": "RSS document or Atom feed (XML)",
  "element": "RSS item or Atom entry (XML)"

imm expects callbacks to return 0 in case of success, or any other exit code in case of failure, in which case the standard error output (stderr) will be displayed.

Example use cases

Online feed reader

For the sake of I-want-the-mutt-of-feed-readers zealots, it is possible to turn any mail reader into a feed reader, by having imm send an e-mail with unread elements to an arbitrary address. You can then browse your feeds through your favourite mail reader, and leverage any mail-related tool on your feeds. Bonus points if your mail reader is online as you can now access your feeds from any computer connected to the Internet.

Here is an example configuration:

let Callback : Type =
  { _executable : Text
  , _arguments : List Text

let sendMail =
  { _executable = "imm-sendmail"
  , _arguments = ["--login", "-u", "", "-P", "password", "-s", "", "-p", "587", "--to", ""]

let config : List Callback = [ sendMail ]
in config

Offline read-it-later

imm is able to store a local copy of unread elements, to read them later while offline for example. External links won't work offline though.

let Callback : Type =
  { _executable : Text
  , _arguments : List Text

let writeFile =
  { _executable = "imm-writefile"
  , _arguments = [ "-d", "/path/to/folder" ]

let config : List Callback = [ writeFile ]
in config

Example usage

  • Subscribe to a feed:

    imm subscribe
  • Import feeds from an OPML file:

    cat feeds.opml | imm import
  • List subscribed feeds:

    imm list
  • Show details about a feed:

    imm show
  • Unsubscribe from a feed:

    imm unsubscribe
  • Check for new elements without executing any action:

    imm --read-only run --no-callbacks
  • Execute configured callbacks for each new element from subscribed feeds:

    imm run