cl-rtmidi is a realtime midi driver for common lisp on linux platform.
it currently supports oss-emulated usb alsa devices, e.g:

(with-midi-oss-in (*default-midi-in-stream* "/dev/midi1")
  (loop (print (read-midi-message *default-midi-in-stream*))))

and also midi transport over UART on embedded linux devices, such as
beaglebone black:

(with-midi-uart-out (*default-midi-out-stream* "/dev/ttyS1")
  (loop
    (sleep 1)
    (write-midi-message (make-instance 'note-on-midi-message
                                       :raw-midi '(144 35 111)))))

This uart method has only been tested on beaglebone black.  Soon I
will also add a backend for alsa sequencer ports, rendering my other
linux midi library, cl-alsaseq, obselete...

In order to set up the uart on arch linux, and give lisp the right
permissions this recipe seems to work:

append this line to uEnv.txt:
capemgr.enable_partno=BB-UART2

then reboot beaglebone black, then type the following unix
incantations:

echo BB-UART2 > /sys/devices/platform/bone_capemgr/slots
stty -F /dev/ttyS2 115200 sane -brkint -icrnl -opost -onlcr -isig -icanon -iexten -echo -echoe;
chmod a+rw /dev/ttyS2 (or add user to the uucp group and logout/login)

obviously everything could be done a bit neater if I was better at
UNIX, but hey if you're reading this I guess you are probably a
paren-slinging lisp badass and won't lose sleep over it...