@GrahamcOfBorg build ocamlPackages.owl

Maybe you could tweak the EIGEN_FLAGS environment variable on Aarch64 (see: https://github.com/owlbarn/eigen/blob/068a74666322f575e32795ee9290b92a30e4a123/eigen/dune#L4-L6). Currently build fails with:

gcc: error: unrecognized command line option '-mfpmath=sse'

@vbgl -- flags adjusted on Aarch64.

Owl itself has the same issue with SSE-related flags, so it might make more sense to set platforms to x86_64 rather than make all these changes manually.

That’s up to you, as maintainer of these packages: do you want to figure out the right installation parameters for these architectures that you don’t use, or just claim that the package is only available for the architecture that you use.

Minor notes:

• eigen-0.1.5 is out
• You don’t have to “substituteInPlace” to change the compilation flags: simply setting the “EIGEN_FLAGS” and “OPTFLAGS0” environment variables should be enough.

Since I have no way to test on these architectures, I've just set platforms to x64 for now, which together with the Eigen version bump simplifies the derivation considerably.

You’ve made a good choice.

Final nitpick: eigen won’t build with OCaml < 4.04 Can you please add a “minimumOCamlVersion” to that derivation? Thanks.

@vbgl - done!

Thanks!