Caleb, although it's a
little bit of a stretch, since the first syllable of
Caleb is not pronounced like
Cal. Still, I think it's doable. Ages ago I asked the question, "If you wanted to use the nickname
Cal, which full name would you prefer,
Calvin or
Caleb?" I do like
Calvin quite a bit more than
Caleb, though. I adore the nickname
Cal.