Interest in polymorphic [[type system]]s developed significantly in the 1990s, with practical implementations beginning to appear by the end of the decade. ''Ad hoc polymorphism'' and ''parametric polymorphism'' were originally described in [[Christopher Strachey]]'s ''[[Fundamental Concepts in Programming Languages]]'',<ref name=Strachey00>{{cite journal |last1=Strachey |first1=Christopher |author1-link=Christopher Strachey |title=Fundamental Concepts in Programming Languages |journal=[[Higher-Order and Symbolic Computation]] |date=2000 |volume=13 |issue=1/2 |pages=11–49 |doi=10.1023/A:1010000313106 |issn=1573-0557 |citeseerx=10.1.1.332.3161 |s2cid=14124601}}</ref> where they are listed as "the two main classes" of polymorphism. Ad hoc polymorphism was a feature of [[AlgolALGOL 68]], while parametric polymorphism was the core feature of [[ML (programming language)|ML]]'s type system.
In a 1985 paper, [[Peter Wegner]] and [[Luca Cardelli]] introduced the term ''inclusion polymorphism'' to model subtypes and [[Inheritance (object-oriented programming)|inheritance]],<ref name="Luca"/> citing [[Simula]] as the first programming language to implement it.
