3. If that works, then type:
- opam init --comp 4.02.1
+ opam init --comp 4.01.0
or whatever it was that the OPAM installer prompted you to type. This will download and install a fresh version of OCaml, and will take a bit of time.
+<!-- To upgrade: opam switch 4.02.1 && eval `opam config env` -->
+
<!--
If you do have Xcode, and want to do without MacPorts, then
what you need to do is download Findlib from