On Wed, Mar 9, 2016 at 10:56 AM, Junsong Li <ljs.darkfish@gmail.com> wrote:
>
>
> I have 4.02.1 OCaml installed on my Mac. opam update; opam upgrade
>

 Sexplib 113.24.0, is only available for ocaml >= 4.02.3
The same is true for all other core packages of this version and above.