According to [1] and [2, Section 3.3], type-classes were first introduced in [3] under the name "parametric overloading". Wadler's work [4] came a little later

According to [1] and [2, Section 3.3], type-classes were first introduced in [3] under the name "parametric overloading". Wadler's work [4] came a little later albeit was (probably) arrived at independently. [1] O. Kieselyov, Increasing Haskell modularity. https://mail.haskell.org/pipermail/haskell-cafe/2014-October/116291.html https://mail.haskell.org/pipermail/haskell-cafe/2014-October... [2] P. Hudak, J. Hughes, S. Peyton Jones, P. Wadler, A History of Haskell: Being Lazy With Class. [3] S. Kaes, Parametric overloading in polymorphic programming languages. [4] P. Wadler, S. Blott, How to make ad-hoc polymorphism less ad hoc.