I've spent the last couple of months on coding a Fortran program for solving a particular PDE system (describes fluid flow/combustion). I tryed to use latest-standard Fortran and the new OOP capabilites modern Fortran has. I am working on my own and have no Fortran guru beside me to ask questions, so a nataral way to learn for me would be to look at other libraries/solvers that use modern Fortran.
Unfortunately all the Fortran libraries out there seem to be written in pretty old Fortran, Fortran90 tops. Therefore I had to think through the class-design and interaction myself. And I am not at all certian that I did it right, especially if one looks from a preformance perspective. But perhaps I have missed something and there are modern scientific packages written if Fortran and using OOP?
There are a lot of good C++ libraries to learn from (OpenFOAM, deal.II and more) and also Python libraries. Those languages have a bigger community in general as well. Is it perhaps better to drop Fortran and switch language if I want to learn by example?