I have a slight problem wherein every time I start up a game of NetHack, I completely loose touch with my surroundings for hours on end. Thankfully The DevTeam Thinks Of Everything and there’s a solution that allows communication with the outside world without breaking immersion: the mail daemon!

If compiled with -DMAIL and OPTIONS=mail (the default on Linux), NetHack will periodically check a user specified mbox file (MAIL) for new mail, and upon receiving an email a mail daemon will spawn in and deliver a scroll of mail to the player. Upon reading this scroll a mail program (MAILREADER) will be executed, which hopefully allows you to read your mail.

I use the Lisp window port to play NetHack (the way God intended), and I really don’t like leaving Emacs, so let’s figure out how to integrate this feature with mu4e. mu uses maildir, not mbox, so I decided to write a cron job that periodically converts my maildir to mbox format.

An important insight is that NetHack never checks the contents of the mailbox file, just the mtime. Therefore all our script needs to do is check if our maildir contains any messages received within the last $n$ minutes, and if so touch the mbox file.

import os
import mailbox
from datetime import datetime, timedelta
import pathlib

MAILDIR = os.path.expanduser("~/Mail/personal/INBOX")
MBOX = "/tmp/nh.mbox"

maildir = mailbox.Maildir(MAILDIR)
for msg in maildir:
    if datetime.fromtimestamp(msg.get_date()) > datetime.now() - timedelta(minutes=5):
        pathlib.Path(MBOX).touch()
        break
maildir.close()

Next, we need a script that will open up mu4e.

emacsclient -n --eval "(progn (require 'mu4e) (mu4e-context-switch nil \"Personal\") (mu4e-search-bookmark \"maildir:/personal/INBOX AND flag:unread\"))"

I’m using emacsclient instead of plain old emacs partly because only one process at a time can hold the lock on mu’s database, so I don’t want to spin up another Emacs process. It’s also worth mentioning that my emacsclient is wrapped such that it opens a new frame if invoked outside of Emacs and reuses the current frame if invoked from within Emacs:

export _t='-c'
exec "/nix/store/...-emacs/bin/.emacsclient-wrapped"  "${_t/${INSIDE_EMACS:+*}/-u}" -a /nix/store/...-emacs/Applications/Emacs.app/Contents/MacOS/Emacs "$@"

Here’s some riveting gameplay footage of dungeon level 1: