Systems and methods disclosed herein uniquely define each type of Fortran type descriptor within an executable file or shared library to allow for a rapid determination of how the dynamic type of one object (e.g., a first polymorphic entity) relates to that of another object (e.g., a second polymorphic entity) while allowing for the lazy loading of shared libraries. In one aspect, type descriptor definitions are instantiated (e.g., during compile-time) in each object file in which polymorphic entities are defined, each type descriptor definition is marked with a singleton attribute, and each group of common type descriptor definitions is associated with a COMDAT group to ensure that only a single copy of each type descriptor is defined in a corresponding executable file at a particular address in memory to which polymorphic entities can reference. Type descriptor addresses can be compared to determine dynamic type relations between polymorphic entities.