Module Systems

Harper Lillibridge POPL 1994 A Type Theoretic
Approach to Higher Order Modules with Sharing https://www.cs.cmu.edu/~rwh/papers/sharing/popl94.pdf and Stefan Wehr
ML Modules and Haskell Type Classes: A Constructive Comparison http://www.stefanwehr.de/publications/Wehr_ML_modules_and_Haskell_type_classes.pdf