improve type hints based on mypy analysis (#105)

* improve type hints based on mypy analysis

* use cast instead of type: ignore

* create root-level horizontal standard variables with precise domain

* work around missing typing.Final in python 3.7

* try another python 3.7 workaround

* run mypy as part of github actions

* tweaks for online mypy tests

* mypy: install types-pyyaml

* add type hints to fabm_evaluate.py

* install netcdf4 for type checking

* skip mypy checks on python 3.8 (no type-aware netcdf4)

* further improvements to type annotation

* use sys.platform to detect windows

.github/workflows/fabm.yml

@@ -303,6 +303,11 @@ jobs:
           conda install ipython jupyterlab ipympl matplotlib scipy
           cd testcases/python
           for f in *.ipynb; do ipython --gui qt -c "%run $f"; done
+      - name: Type checking with mypy
+        if: matrix.python-version != '3.7' && matrix.python-version != '3.8'
+        run: |
+          conda install mypy pyyaml types-pyyaml netcdf4 pyqt-stubs
+          mypy src/pyfabm
       - name: Install with customization via command line arguments
         run: |
           rm -rf build

src/fabm_coupling.F90

@@ -339,7 +339,8 @@ recursive subroutine process_coupling_tasks(self, final, log_unit)
                      standard_variable=standard_variable, presence=presence_external_optional, link=link)
                class is (type_horizontal_standard_variable)
                   call root%add_horizontal_variable(standard_variable%name, standard_variable%units, standard_variable%name, &
-                     standard_variable=standard_variable, presence=presence_external_optional, link=link)
+                     standard_variable=standard_variable, presence=presence_external_optional, link=link, &
+                     domain=standard_variable2domain(standard_variable))
                class is (type_global_standard_variable)
                   call root%add_scalar_variable(standard_variable%name, standard_variable%units, standard_variable%name, &
                      standard_variable=standard_variable, presence=presence_external_optional, link=link)