POP-2

POP-2, also called POP2, is a programming language developed around 1970 by Robin Popplestone and Rod Burstall at the University of Edinburgh, growing out of an earlier language called POP-1. It is a multi paradigm language combining structured, reflective and procedural approaches, drawing on ideas from both Lisp and ALGOL 60, and it used an incremental compiler that gave it some of the flexibility of an interpreted language while avoiding much of the performance overhead interpretation usually carries. The language allowed functions to be defined and modified while a program was running, and its stack based design reversed ordinary assignment syntax, so a value was written into a variable with an arrow notation rather than the more familiar assignment operator, reflecting its explicit operand stack model. POP-2 spawned several descendants, most notably POP-11, developed by Steve Hardy at Sussex University, which became the dominant variant of the family and remains available today through the Poplog programming environment alongside Prolog, Common Lisp and Standard ML.