### .tmux.conf
bind-key v command-prompt -p "enter digraph:" "set-buffer \"%%\"; save-buffer /tmp/tmux-input; delete-buffer; if-shell '/home/username/bin/digraph.py < /tmp/tmux-input > /tmp/tmux-output' 'load-buffer /tmp/tmux-output; paste-buffer -d; run-shell \"rm /tmp/tmux-output /tmp/tmux-input\"'"

### digraph.py [python]
#!/usr/bin/python
import logging
import os.path
import sys
import unicodedata

logfile = os.path.join(os.path.dirname(__file__), 'exceptions.log')
logging.basicConfig(filename=logfile)

COMBINE_MAP = {
    "`": u'\u0300',
    "!": u'\u0300',
    "'": u'\u0301',
    '"': u'\u0301',
    "^": u'\u0302',
    "~": u'\u0303',
    "-": u'\u0304',
    ":": u'\u0308',
}

REPLACE = {
    "...": u'\N{HORIZONTAL ELLIPSIS}',
    "``": u'\N{LEFT DOUBLE QUOTATION MARK}',
    "''": u'\N{RIGHT DOUBLE QUOTATION MARK}',
    "<3": u'\N{BLACK HEART SUIT}',
    "--": u'\N{EM DASH}',
    "AE": u'\N{LATIN CAPITAL LETTER AE}',
    "ae": u'\N{LATIN SMALL LETTER AE}',
    "s":  u'\N{LATIN SMALL LETTER LONG S}',
    "ss": u'\N{LATIN SMALL LETTER SHARP S}',
}

def main(value):
    if value.startswith('U+'):
        value = value[2:]
        sys.stdout.write(unichr(int(value, 16)).encode('utf8'))
        return
    if value in REPLACE:
        sys.stdout.write(REPLACE[value].encode('utf8'))
        return
    if len(value) != 2:
        raise Exception("invalid value: " + value)
    if value[1] in COMBINE_MAP:
        s = value[0].decode('ascii') + COMBINE_MAP[value[1]]
        s = unicodedata.normalize('NFC', s)
        sys.stdout.write(s.encode('utf8'))
        return
    raise Exception("invalid value: " + value)

if __name__ == '__main__':
    try:
        main(sys.stdin.read())
    except Exception, e:
        logging.exception('blargh')
        raise