Ocaml wants to install its "core" libraries in OCAML_CORE_STDLIB.  That
does not work in a store-based distribution.

A solution was already provided by Nix

    https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/ocaml/findlib/install_topfind.patch

regenerated for Guix.

--- findlib-1.5.3/src/findlib/Makefile	2014-09-16 13:21:46.000000000 +0200
+++ findlib-1.5.3/src/findlib/Makefile.new	2014-10-01 14:30:54.141082521 +0200
@@ -89,7 +89,7 @@
 install: all
 	mkdir -p "$(prefix)$(OCAML_SITELIB)/$(NAME)"
 	mkdir -p "$(prefix)$(OCAMLFIND_BIN)"
-	test $(INSTALL_TOPFIND) -eq 0 || cp topfind "$(prefix)$(OCAML_CORE_STDLIB)"
+	test $(INSTALL_TOPFIND) -eq 0 || cp topfind "$(prefix)$(OCAML_SITELIB)"
 	files=`$(TOP)/tools/collect_files $(TOP)/Makefile.config findlib.cmi findlib.mli findlib.cma topfind.cmi topfind.mli fl_package_base.mli fl_package_base.cmi fl_metascanner.mli fl_metascanner.cmi fl_metatoken.cmi findlib_top.cma findlib.cmxa findlib.a findlib.cmxs findlib_dynload.cma findlib_dynload.cmxa findlib_dynload.a findlib_dynload.cmxs fl_dynload.mli fl_dynload.cmi META` && \
 	cp $$files "$(prefix)$(OCAML_SITELIB)/$(NAME)"
 	f="ocamlfind$(EXEC_SUFFIX)"; { test -f ocamlfind_opt$(EXEC_SUFFIX) && f="ocamlfind_opt$(EXEC_SUFFIX)"; }; \
b758f3c7063a84641c98870b1d'>tree</a><a href='/guix/commit/tests/guix-hash.sh?id=1f2b4228b580b8b758f3c7063a84641c98870b1d'>commit</a><a href='/guix/diff/tests/guix-hash.sh?id=1f2b4228b580b8b758f3c7063a84641c98870b1d'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/guix-hash.sh'>
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<div class='path'>path: <a href='/guix/log/?id=1f2b4228b580b8b758f3c7063a84641c98870b1d'>root</a>/<a href='/guix/log/tests?id=1f2b4228b580b8b758f3c7063a84641c98870b1d'>tests</a>/<a href='/guix/log/tests/guix-hash.sh?id=1f2b4228b580b8b758f3c7063a84641c98870b1d'>guix-hash.sh</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/guix-hash.sh?id=1f2b4228b580b8b758f3c7063a84641c98870b1d&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-09-28 21:06:36 -0500'>2020-09-28</span></td><td><a href='/guix/commit/tests/guix-hash.sh?id=d8934360d2453a403b5433e71d09188e4ed23b57'>tests: Simplify shell exit status negation;</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/guix-archive.sh, tests/guix-build-branch.sh, tests/guix-build.sh,
tests/guix-daemon.sh, tests/guix-download.sh, tests/guix-environment.sh,
tests/guix-gc.sh, tests/guix-git-authenticate.sh, tests/guix-graph.sh,
tests/guix-hash.sh, tests/guix-lint.sh, tests/guix-pack-relocatable.sh,
tests/guix-pack.sh, tests/guix-package-aliases.sh, tests/guix-package-net.sh,
tests/guix-package.sh: Use the shell '!' keyword to negate command exit status
in place of 'if ...; then false; else true; fi'
</span></span></td><td>Eric Bavier</td></tr>
<tr><td><span title='2020-05-22 00:35:24 +0200'>2020-05-22</span></td><td><a href='/guix/commit/tests/guix-hash.sh?id=0e4e9c8e7655f3e2a9c2615923768d211ac02a3e'>guix hash, guix download: Support base64 format.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/scripts/download.scm (show-help, %options): Support "base64"
format.
* guix/scripts/hash.scm (show-help, %options): Likewise.
* tests/guix-hash.sh: Test it.
* doc/guix.texi (Invoking guix hash): Document it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-05-22 00:35:24 +0200'>2020-05-22</span></td><td><a href='/guix/commit/tests/guix-hash.sh?id=18ae1ec3ecfe22d55d6cdf595a442afebbc5595a'>guix hash, guix download: Add '--hash'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/scripts/download.scm (%default-options): Add 'hash-algorithm'.
(show-help, %options): Add "--hash".
(guix-download): Honor it.
* guix/scripts/hash.scm (%default-options): Add 'hash-algorithm'.
(show-help, %options): Add "--hash".
(guix-hash): Honor it.
* tests/guix-hash.sh: Test '-H sha512'.
* doc/guix.texi (Invoking guix download): Document it.
(Invoking guix hash): Document it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-10-28 22:30:17 +0200'>2016-10-28</span></td><td><a href='/guix/commit/tests/guix-hash.sh?id=343dc11702bf71876795b5d158cad860deca53a1'>guix hash: Interpret '-' as standard input.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/scripts/hash.scm (guix-hash)[file-hash]: Special-case "-".
* tests/guix-hash.sh: Add test.
* doc/guix.texi (Invoking guix hash): Document it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-09-07 12:00:35 +0200'>2016-09-07</span></td><td><a href='/guix/commit/tests/guix-hash.sh?id=392a4e122350367c4b4ac331db5ec28360c7f38c'>guix hash: Add --exclude-vcs option.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/scripts/hash.scm (show-help): Add help text for --exclude-vcs option.
(%options): Add --exclude-vcs option.
(guix-hash): Handle exclude-vcs option.
* doc/guix.texi ("Invoking guix hash"): Update doc.
* tests/guix-hash.sh: Add test.

Co-authored-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Jan Nieuwenhuizen</td></tr>