tripleFromGen :: RDF g => (g -> Triples) -> g -> Gen (Maybe Triple)
tripleFromGen _triplesOf gr =
  case null ts of
    True  -> return Nothing
    False -> oneof $ map (return . Just) ts
  where ts = _triplesOf gr
tripleFromGen :: RDF g => (g -> Triples) -> g -> Gen (Maybe Triple)
tripleFromGen _triplesOf gr =
  case null ts of
    True  -> return Nothing
    False -> oneof $ map (return . Just) ts
  where ts = _triplesOf gr
tripleFromGen _triplesOf gr =
  case null ts of
    True  -> return Nothing
    False -> oneof $ map (return . Just) ts
  where ts = _triplesOf gr