This is a very good point. I initially just used declarations like real(sp), intent(in) :: x(:,:), but there are lots of arrays and it quickly became really hard to ensure I didn’t make a mistake. So I reverted to the style of real(sp), intent(in) :: x(n_embd,n_seq) where the compiler can check the compatibility of arrays (typically at runtime) and that helped a lot to catch bugs, that I multiply matrices correctly, and loop over the correct bounds, etc. In Python the indices are reverted (column vs row major), so it’s really easy to get it wrong. I also found it’s nicer to document what each index is doing directly like this, rather than having it as comments. I could infer it and still set dimensions of everything, but that becomes very hard to read if you have size(x, 1) everywhere. Much more natural to use the problem parameters like n_embd, n_seq, or n_layers.
See my proposal here for how this can be improved: How to concisely declare a function result as a multi-dimensional automatic array? - #4 by certik