History of Programming Languages (HOPL) is an infrequent ACM SIGPLAN conference.
[2] From Sammet's introduction: The HOPL Conference "is intended to consider the technical factors which influenced the development of certain selected programming languages."
The papers and presentations went through extensive review by the program committee (and revisions by the authors), far beyond the norm for conferences and commensurate with some of the best journals in the field.
[3] The final proceedings, including transcripts of question and answer sessions, was published as a book titled History of Programming Languages.
[5] The final proceedings, including copies of the presentations and transcripts of question and answer sessions, was published as the book titled History of Programming Languages II.
HOPL III had an open call for participation and asked for papers on either the early history or the evolution of programming languages.
The HOPL III languages can be broadly categorized into five classes (or paradigms): Object-oriented (Modula-2, Oberon, C++, Self, Emerald, BETA), Functional (Haskell), Scripting (AppleScript, Lua), Reactive (Erlang, Statecharts), and Parallel (ZPL, High Performance Fortran).