In rawhide on x86_64, I see the following -devel packages for the i686
architecture:
ocaml-SDL-devel-0.9.1-1.fc21.i686
ocaml-ancient-devel-0.9.0-13.fc21.i686
ocaml-apron-0.9.10-13.fc21.i686
ocaml-apron-devel-0.9.10-13.fc21.i686
ocaml-augeas-devel-0.5-6.fc21.i686
ocaml-bin-prot-devel-2.0.9-6.fc21.i686
ocaml-bisect-devel-1.3-1.fc21.i686
ocaml-bitstring-devel-2.0.4-3.fc21.i686
ocaml-cairo-devel-1:1.2.0-0.11.git08b40192975.fc21.i686
ocaml-calendar-devel-2.03.2-5.fc21.i686
ocaml-camlidl-devel-1.05-21.fc21.i686
ocaml-camlimages-4.1.0-2.fc21.i686
ocaml-camlimages-devel-4.1.0-2.fc21.i686
ocaml-camlp4-devel-4.01.0-3.fc21.i686
ocaml-camlp5-devel-6.11-1.fc21.i686
ocaml-camomile-devel-0.8.3-13.fc21.i686
ocaml-cil-devel-1.7.3-3.fc21.i686
ocaml-cryptokit-devel-1.9-1.fc21.i686
ocaml-csv-devel-1.3.1-1.fc21.i686
ocaml-curl-devel-0.5.3-10.fc21.i686
ocaml-curses-devel-1.0.3-18.fc21.i686
ocaml-dbus-devel-0.29-9.fc21.i686
ocaml-deriving-devel-0.1.1a-20.fc21.i686
ocaml-expat-devel-0.9.1-27.fc21.i686
ocaml-extlib-devel-1.5.4-1.fc21.i686
ocaml-facile-devel-1.1-22.fc21.i686
ocaml-fileutils-devel-0.4.5-1.fc21.i686
ocaml-findlib-devel-1.4-1.fc21.i686
ocaml-gettext-camomile-devel-0.3.4-11.fc21.i686
ocaml-gettext-devel-0.3.4-11.fc21.i686
ocaml-gsl-devel-1.13.0-1.fc21.i686
ocaml-hivex-devel-1.3.8-4.fc21.i686
ocaml-json-static-0.9.8-11.fc21.i686
ocaml-json-wheel-devel-1.0.6-13.fc21.i686
ocaml-lablgl-devel-20120306-7.fc21.i686
ocaml-lablgtk-devel-2.18.0-1.fc21.i686
ocaml-labltk-devel-4.01.0-3.fc21.i686
ocaml-lacaml-7.0.9-2.fc21.i686
ocaml-lacaml-devel-7.0.9-2.fc21.i686
ocaml-libguestfs-devel-1:1.23.22-2.fc21.i686
ocaml-libvirt-devel-0.6.1.2-9.fc21.i686
ocaml-lwt-2.4.3-4.fc21.i686
ocaml-lwt-devel-2.4.3-4.fc21.i686
ocaml-menhir-20130911-2.fc21.i686
ocaml-menhir-devel-20130911-2.fc21.i686
ocaml-mikmatch-devel-1.0.6-4.fc21.i686
ocaml-mlgmpidl-devel-1.2.1-0.5.20120830.fc21.i686
ocaml-mysql-devel-1.1.1-6.fc21.i686
ocaml-newt-devel-0.9-17.fc21.i686
ocaml-ocamlgraph-devel-1.8.3-5.fc21.i686
ocaml-ocamlnet-devel-3.7.3-4.fc21.i686
ocaml-ocamlnet-nethttpd-devel-3.7.3-4.fc21.i686
ocaml-ounit-devel-1.1.2-7.fc21.i686
ocaml-p3l-devel-2.03-15.fc21.i686
ocaml-pa-do-devel-0.8.16-1.fc21.i686
ocaml-pcre-devel-7.0.2-5.fc21.i686
ocaml-perl4caml-devel-0.9.5-28.fc21.i686
ocaml-pgocaml-devel-1.6-5.fc21.i686
ocaml-postgresql-devel-2.0.4-1.fc21.i686
ocaml-preludeml-devel-0.1-0.25.20100314.fc21.i686
ocaml-pxp-devel-1.2.4-1.fc21.i686
ocaml-react-0.9.4-4.fc21.i686
ocaml-react-devel-0.9.4-4.fc21.i686
ocaml-reins-devel-0.1a-17.fc21.i686
ocaml-res-devel-4.0.3-1.fc21.i686
ocaml-sexplib-devel-7.0.5-7.fc21.i686
ocaml-sqlite-2.0.4-2.fc21.i686
ocaml-sqlite-devel-2.0.4-2.fc21.i686
ocaml-ssl-devel-0.4.6-9.fc21.i686
ocaml-tplib-1.3-5.fc21.i686
ocaml-tplib-devel-1.3-5.fc21.i686
ocaml-ulex-devel-1.1-18.fc21.i686
ocaml-xml-light-devel-2.3-0.6.svn234.fc21.i686
ocaml-xmlrpc-light-devel-0.6.1-14.fc21.i686
ocaml-zarith-1.2.1-4.fc21.i686
ocaml-zarith-devel-1.2.1-4.fc21.i686
ocaml-zip-devel-1.05-1.fc21.i686
If I'm not mistaken, these are unusable because the i686 compilers
cannot be installed on x86_64 installation. I suppose they would go
away if they declared a proper dependency on ocaml.i686.