Source : Free On-Line Dictionary of Computing

POPLOG
     
        A multi-language programming environment, which includes the
        languages {Pop-11}, {ML}, {Common Lisp} and {Prolog}.  It
        supports mixed-language programming and {incremental
        compilation} and includes a comprehensive {X Window System}
        interface.  It is built on top of a two-stack {virtual
        machine}, PVM.  POPLOG was developed at the University of
        Sussex, Brighton, UK.
     
        ["POPLOG's Two-Level Virtual Machine Support for Interactive
        Languages", R. Smith et al, in Research Directions in
        Cognitive Science, v.5 (1992)].