I don't mind single-letter names, but I dislike having the same letter used with different case for two different names. In this example I'd probably have a lif

I don't mind single-letter names, but I dislike having the same letter used with different case for two different names. In this example I'd probably have a lifetime 'l, a seed S, and a copy C. That way there's no "s" vs "capital s" confusion when saying what the names are.