Hi Junsong, It's possible that you have a package installed that has no version compatible with sexplib 113.24. You can try to explicitly upgrade sexplib to see what solution opam suggests On Wed, Mar 9, 2016 at 3:56 PM, Junsong Li wrote: > Hi Jeremie, > > I have 4.02.1 OCaml installed on my Mac. opam update; opam upgrade > didn't upgrade the sexplib to 113.24. opam list still shows 113.00. > Any ideas? > > My fresh installed 4.02.3 OCaml on a Linux machine has 113.24 sexplib > though. > > On Fri, Feb 5, 2016 at 1:36 AM, Jeremie Dimino > wrote: > > On Wed, Feb 3, 2016 at 7:20 PM, ygrek wrote: > >> > >> I wonder if keeping empty sexplib.syntax subpackage with only > >> requires="pa_sexp_conv" line > >> will prevent build breakage (one will only need to fix opam > dependencies)? > > > > > > That would work for now. However, sooner or latter some change in > > > > sexplib will break the code generated by pa_sexp_conv and we'll have the > > same problem again. > > The current forced upgrade is simple (one sed command [1]) and it's a > hint > > that it's a good time to switch to ppx. We published a tool to help with > > this BTW [2] > > > > [1] https://github.com/ocaml/opam-repository/blob/master/CHANGES.md > > [2] > https://blogs.janestreet.com/converting-a-code-base-from-camlp4-to-ppx > > > > https://github.com/janestreet/camlp4-to-ppx > > > > -- > > Jeremie > -- Jeremie