Why would that be enough on its own? If that alone is sufficient, he should choose C over both OCaml and Haskell.
Haskell comes with a very big community, and a lot of ways to start with the languages. I think about the http://learnyouahaskell.com/ and others.
Real World OCaml is that, without totally being it. The authors wrote it with the idea in mind that only people with a good background about functionnal world can read it.
I'd add that lazyness can be a good thing and that the type-system of Haskell is better than the OCaml one.
Isn't that enough to choose OCaml over Haskell?