refs :: Entry -> [String]
refs e@(Entry _ p) = fromMaybe [] $ do
  f <- lookup "from" c
  t <- lookup "to"   c
  return [name e, f, t]
  where
  c = catProps p
refs :: Entry -> [String]
refs e@(Entry _ p) = fromMaybe [] $ do
  f <- lookup "from" c
  t <- lookup "to"   c
  return [name e, f, t]
  where
  c = catProps p
refs e@(Entry _ p) = fromMaybe [] $ do
  f <- lookup "from" c
  t <- lookup "to"   c
  return [name e, f, t]
  where
  c = catProps p