References for parametricity

• Categorical models of parametricity

  • Parametric limits

  • Domain-theoretic models of parametric polymorphism

  • Reflexive graphs and parametric polymorphism

• Unary parametricity versus binary parametricity

  The definition of “relation” and “identity relation” in parametricity is actually a bit up for grabs, and this freedom is actually essential if you want to support fancy types like higher kinds or dependent types, or wish to work with fancier semantic structures.