joseph leslie armstrong (27 december 1950 – 20 april 2019) was a british computer scientist. he is best known as one of the co-designers of the erlang programming language. he was given a ph.d. in computer science from kth royal institute of technology (kth) in stockholm, sweden in 2004. he later became a professor at kth from 2014. he was born in bournemouth, hampshire.