maybe you should vendor the version of arrow which is supported

[UnixJunkie]

Hence, the opam package can install everything required, even if the system doesn't have the package installed. Since the arrow package is not included in many distros, that would be interesting.

[UnixJunkie]

I don't know which version of arrow you support, by the way.

# opam depext -i arrow
# Detecting depexts using vars: arch=x86_64, os=linux, os-distribution=ubuntu, os-family=debian
# The following system packages are needed:
libffi-dev
pkg-config
# All required OS packages found.
# Now letting OPAM install the packages

<><> Synchronising pinned packages ><><><><><><><><><><><><><><><><><><><><><><>
[arrow.dev] no changes from git+https://github.com/LaurentMazare/ocaml-arrow.git

The following actions will be performed:
  - install arrow dev*

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ERROR] The compilation of arrow failed at "/home/berenger/.opam/opam-init/hooks/sandbox.sh build dune build -p arrow -j 12".

#=== ERROR while compiling arrow.dev ==========================================#
# context     2.0.5 | linux/x86_64 | ocaml-base-compiler.4.12.0 | pinned(git+https://github.com/LaurentMazare/ocaml-arrow.git#b1563b55)
# path        ~/.opam/4.12.0/.opam-switch/build/arrow.dev
# command     ~/.opam/opam-init/hooks/sandbox.sh build dune build -p arrow -j 12
# exit-code   1
# env-file    ~/.opam/log/arrow-1041404-d8a4ae.env
# output-file ~/.opam/log/arrow-1041404-d8a4ae.out
### output ###
# [...]
# /usr/include/arrow-glib/array-builder.h:220:10: note: declared here
#   220 | gboolean garrow_uint_array_builder_append_null(GArrowUIntArrayBuilder *builder,
#       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# arrow_stubs.c: In function 'caml__553_garrow_uint_array_builder_append_nulls':
# arrow_stubs.c:4352:4: warning: 'garrow_uint_array_builder_append_nulls' is deprecated: Use 'garrow_array_builder_append_nulls' instead [-Wdeprecated-declarations]
#  4352 |    int x3167 = garrow_uint_array_builder_append_nulls(x3162, x3163, x3166);
#       |    ^~~
# In file included from /usr/include/arrow-glib/arrow-glib.h:26,
#                  from arrow_stubs.c:1:
# /usr/include/arrow-glib/array-builder.h:223:10: note: declared here
#   223 | gboolean garrow_uint_array_builder_append_nulls(GArrowUIntArrayBuilder *builder,
#       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
+- The following actions failed
| - build arrow dev
+- 
- No changes have been performed
# Run eval $(opam env) to update the current shell environment

[LaurentMazare]

The old glib bit is deprecated, I'll clean that up. The currently active part is under c_api (plus the ppx) and should work with arrow 4.0.0 and 4.0.1 (the currently active version). Vendoring the library itself would probably be the easiest from a user perspective though there have been a bit of pushback on putting binary dependencies in opam rather than rebuilding them from scratch (and rebuilding is probably tricky).

[UnixJunkie]

I did not see a INSTALL file in arrow, so building from sources looks kind of problematic indeed (I suspect there are many dependencies too). Apparently, the pip package pyarrow also provides pre-compiled binaries so that might indicate one path that can be followed.