macosocamlopamcamlp4lwt

making OPAM work with system compiler under MacOS X


I am trying to do a very basic installation of OPAM under MacOS. Using macports I've installed following packages:

  1. opam @1.2.0
  2. ocaml-findlib @1.5.5
  3. ocaml-camlp4 @4.02.0.1_1

when I did opam init (not as root, since I only need it for one user). opam switch shows me that I am using system compiler:

system C system System compiler (4.02.1)

Then I tried to install 'lwt' via opam it failed halfway with errors:

# ocamlfind: Package `camlp4' not found
# W: Failure("Command ''/Users/lord/.opam/system/bin/ocamlfind' query -format %d camlp4 > '/var/folders/hh/h6kt24208xj44z0059_xd9rh0000gn/T/oasis-ca8248.txt'' terminated with error code 2")

This is my opam list:

# Installed packages for system:
base-bigarray           base  Bigarray library distributed with the OCaml compil
base-threads            base  Threads library distributed with the OCaml compile
base-unix               base  Unix library distributed with the OCaml compiler
camlp4         4.02.1+system  Camlp4 is a system for writing extensible parsers
ocamlfind              1.5.5  A library manager for OCaml

I have noticed that it has it own ocamlfind, not system one. Perhaps this is what is causing error:

$ /Users/lord/.opam/system/bin/ocamlfind query -format %d camlp4
ocamlfind: Package `camlp4' not found

$ /opt/local/bin/ocamlfind query -format %d camlp4
/opt/local/lib/ocaml/camlp4

I tried before installing OCAML compiler and CAMLP via OPAM and it this case it works, but it bothers me that I have two compiler installations for the same version. I would rather use system OCAML compiler and CAMLP, if possible.


Solution

  • I'm not sure what goes wrong on your installation, maybe you shouldn't install ocaml-findlib as they may conflict in some manner. I will look at this later. Currently, the following works

    $ sudo port install ocaml ocaml-camlp4 opam
    $ opam init
    $ opam install ocamlfind
    

    This will lead to a working installation:

    $ ocamlfind query camlp4
    /opt/local/lib/ocaml/camlp4
    $ which ocamlfind
    /Users/ivg/.opam/system/bin/ocamlfind
    

    Update

    I've checked my hypothesis that system's ocamlfind may conflict with the opam's one. It doesn't get any evidence. Even if you install both of them everything works fine:

    $ sudo port install ocaml-findlib
    $ opam init
    

    System's ocamlfind works pretty well:

    $ ocamlfind query camlp4
    /opt/local/lib/ocaml/camlp4
    $ which ocamlfind
    /opt/local/bin/ocamlfind
    

    Now let's try to install it from opam:

    $ opam install ocamlfind
    

    It also works pretty well:

    $ ocamlfind query camlp4
    /opt/local/lib/ocaml/camlp4
    $ which ocamlfind
    /Users/ivg/.opam/system/bin/ocamlfind
    

    And

    $ opam install lwt
    

    worked pretty fine too.

    So, maybe you moved somewhere in a wrong direction, and you can just remove your ~/.opam and start from scratch. And also, I hope that you didn't forget to activate your opam with magical:

    $ eval `opam config env`
    

    command.