The evolution of Smalltalk: from Smalltalk-72 through Squeak

Abstract

This paper presents a personal view of the evolution of six generations of Smalltalk in which the author played a part, starting with Smalltalk-72 and progressing through Smalltalk-80 to Squeak and Etoys. It describes the forces that brought each generation into existence, the technical innovations that characterized it, and the growth in understanding of object-orientation and personal computing that emerged. It summarizes what that generation achieved and how it affected the future, both within the evolving group of developers and users, and in the outside world. The early Smalltalks were not widely accessible because they ran only on proprietary Xerox hardware; because of this, few people have experience with these important historical artifacts. To make them accessible, the paper provides links to live simulations that can be run in present-day web browsers. These simulations offer the ability to run pre-defined scripts, but also allow the user to go off-script, browse the details of the implementation, and try anything that could be done in the original system. An appendix includes anecdotal and technical aspects of how examples of each generation of Smalltalk were recovered, and how order was teased out of chaos to the point that these old systems could be brought back to life.