[mod4 (modulepath)]$ module purge
[mod4 (modulepath)]$ module load pgi/18.4
[mod4 (modulepath)]$ module load openmpi/3.1
[mod4 (modulepath)]$ module load foo/1.1
[mod4 (modulepath)]$ module list
Currently Loaded Modulefiles:
 1) pgi/18.4   2) openmpi/3.1   3) foo/1.1
[mod4 (modulepath)]$ foo
foo 1.1 (pgi/18.4, openmpi/3.1)
[mod4 (modulepath)]$ module switch --auto pgi intel/2018
Switching from pgi/18.4 to intel/2018
  Unloading dependent: foo/1.1 openmpi/3.1
  Reloading dependent: openmpi/3.1 foo/1.1
[mod4 (modulepath)]$ module list
Currently Loaded Modulefiles:
 1) intel/2018   2) openmpi/3.1   3) foo/1.1
[mod4 (modulepath)]$ foo
foo 1.1 (intel/2018, openmpi/3.1)
[mod4 (modulepath)]$ mpirun
mpirun (openmpi/3.1, intel/2018)
[mod4 (modulepath)]$ module purge
[mod4 (modulepath)]$ module load intel/2019
[mod4 (modulepath)]$ module load foo
[mod4 (modulepath)]$ module list
Currently Loaded Modulefiles:
 1) intel/2019   2) foo/2.4
[mod4 (modulepath)]$ foo
foo 2.4 (intel/2019, nompi)
[mod4 (modulepath)]$ module load openmpi
[mod4 (modulepath)]$ module list
Currently Loaded Modulefiles:
 1) intel/2019   2) foo/2.4   3) openmpi/4.0
[mod4 (modulepath)]$ foo
foo 2.4 (intel/2019, nompi)