Lately, certain OCaml programs stopped working properly with an `unknown C primitive` error.
The concrete message was:
Fatal error: unknown C primitive `caml_ba_dim_1'
after I used OPAM to install a new version of the OCaml compiler.
Sometimes it worked, and sometimes it didn't which finally lead to
a problem with environment variables. I found the following situation:
~/.opam/opam-init/variables.sh, the environment variable
CAML_LD_LIBRARY_PATH was set to both the OPAM-related path
~/.opam/4.01.0/lib/stublibs and the system installed compiler's
stublibs as well
/usr/local/lib/ocaml/stublibs. After I removed
the latter, everything worked fine.