POP-11

POP-11 is a reflective, incrementally compiled programming language with many of the features of an interpreted language. It is the core language of the Poplog programming environment developed originally by the University of Sussex, and recently in the School of Computer Science at the University of Birmingham which hosts the Poplog website.

POP-11 is an evolution of the language POP-2, developed in Edinburgh University and features an open stack model (like Forth, among others). It is mainly procedural, but supports declarative language constructs, including a pattern matcher and is mostly used for research and teaching in Artificial Intelligence, although it has features sufficient for many other classes of problems. It is often used to introduce symbolic programming techniques to programmers of more conventional languages like Pascal, who find POP syntax more familiar than that of Lisp. One of POP-11's features is that it supports first-class functions.

Pop-11 is the core language of the Poplog system. The fact that the compiler and compiler subroutines are available at run-time (a requirement for incremental compilation) gives it the ability to support a far wider range of extensions than would be possible using only a macro facility. This made it possible for incremental compilers to be added for Prolog, Common Lisp and Standard ML, which could be added as required to support either mixed language development or development in the second language without using any Pop-11 constructs. This made it possible for Poplog to be used by teachers, researchers, or developers who were interested in only one of the languages. The most successful product developed in Pop-11 was the Clementine data-mining system, developed by ISL, as described in the entry on Poplog. After SPSS bought ISL they decided to port Clementine to C++ and Java, and eventually succeeded with great effort (and perhaps some loss of the flexibility provided by the use of an AI language!).