"A Kernel Language for Modules and Abstract Data Types."
R. Burstall and B. Lampson.
September 1, 1984. 51 pages.

Authors' Abstract

    A small set of constructs can simulate a wide variety of apparently
    distinct features in modern programming languages.  Using a kernel
    language called Pebble based on the typed lambda calculus with
    bindings, declarations, and types as first-class values, we show
    how to build modules, interfaces and implementations, abstract
    data types, generic types, recursive types, and unions.  Pebble
    has a concise operational semantics given by inference rules.