> Algebraic data types were introduced in Hope, a small functional programming language developed in the 1970s at the University of Edinburgh. [0]

It predates Miranda and Haskell and is contemporaneous with ML, also developed at the University. [1]

ML had them too [2]

[0] https://en.wikipedia.org/wiki/Algebraic_data_type#Programmin...

[1] https://en.wikipedia.org/wiki/Hope_(programming_language)

[2] https://en.wikipedia.org/wiki/ML_(programming_language)

edit: add ML