[rho_soul_kg_m3]

Thanks. Regarding open-sourcing, well no, it's not up to me, and it would be kind of proprietary.

The size variants for floats and integers is definitely appreciated.

For the "read-only BigArrays": At the time I didn't know any Rust, but today that would simply be passing a mutable or immutable reference. Similar to the Fortran in/out designators in some way. I think that's pretty important when you have some complicated numerical code, sometimes with in-place modification.

Since there is a "zero_alloc checker", maybe a similar kind of annotation exists or could be added? Something like

  let foo (x : [@readonly]) = ... 
    x.{0} <- 1.23

  ^ Attempt to write to read-only array