Smalltalk

Smalltalk is an object-oriented, dynamically typed reflective programming language. Smalltalk was created as the language in underpinning the 'new world' of computing exemplified by 'human–computer symbiosis'. It was designed and created in part for educational use, more so for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by Alan Kay, Dan Ingalls, Adele Goldberg, Ted Kaehler, Scott Wallace, and others during the 1970s. Smalltalk is an object-oriented, dynamically typed reflective programming language. Smalltalk was created as the language in underpinning the 'new world' of computing exemplified by 'human–computer symbiosis'. It was designed and created in part for educational use, more so for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by Alan Kay, Dan Ingalls, Adele Goldberg, Ted Kaehler, Scott Wallace, and others during the 1970s. The language was first generally released as Smalltalk-80. Smalltalk-like languages are in continuing active development and have gathered loyal communities of users around them. ANSI Smalltalk was ratified in 1998 and represents the standard version of Smalltalk. Smalltalk took second place for 'most loved programming language' in the Stack Overflow Developer Survey in 2017, but it was not among the 26 most loved programming languages of the 2018 survey. There are a large number of Smalltalk variants. The unqualified word Smalltalk is often used to indicate the Smalltalk-80 language, the first version to be made publicly available and created in 1980. Smalltalk was the product of research led by Alan Kay at Xerox Palo Alto Research Center (PARC); Alan Kay designed most of the early Smalltalk versions, Adele Goldberg wrote most of the documentation, and Dan Ingalls implemented most of the early versions. The first version, termed Smalltalk-71, was created by Kay in a few mornings on a bet that a programming language based on the idea of message passing inspired by Simula could be implemented in 'a page of code'. A later variant used for research work is now termed Smalltalk-72 and influenced the development of the Actor model. Its syntax and execution model were very different from modern Smalltalk variants. After significant revisions which froze some aspects of execution semantics to gain performance (by adopting a Simula-like class inheritance model of execution), Smalltalk-76 was created. This system had a development environment featuring most of the now familiar tools, including a class library code browser/editor. Smalltalk-80 added metaclasses, to help maintain the 'everything is an object' (except private instance variables) paradigm by associating properties and behavior with individual classes, and even primitives such as integer and boolean values (for example, to support different ways to create instances). Smalltalk-80 was the first language variant made available outside of PARC, first as Smalltalk-80 Version 1, given to a small number of firms (Hewlett-Packard, Apple Computer, Tektronix, and Digital Equipment Corporation (DEC)) and universities (UC Berkeley) for peer review and implementing on their platforms. Later (in 1983) a general availability implementation, named Smalltalk-80 Version 2, was released as an image (platform-independent file with object definitions) and a virtual machine specification. ANSI Smalltalk has been the standard language reference since 1998. Two of the currently popular Smalltalk implementation variants are descendants of those original Smalltalk-80 images. Squeak is an open source implementation derived from Smalltalk-80 Version 1 by way of Apple Smalltalk. VisualWorks is derived from Smalltalk-80 version 2 by way of Smalltalk-80 2.5 and ObjectWorks (both products of ParcPlace Systems, a Xerox PARC spin-off company formed to bring Smalltalk to the market). As an interesting link between generations, in 2001 Vassili Bykov implemented Hobbes, a virtual machine running Smalltalk-80 inside VisualWorks. (Dan Ingalls later ported Hobbes to Squeak.) During the late 1980s to mid-1990s, Smalltalk environments—including support, training and add-ons—were sold by two competing organizations: ParcPlace Systems and Digitalk, both California based. ParcPlace Systems tended to focus on the Unix/Sun microsystems market, while Digitalk focused on Intel-based PCs running Microsoft Windows or IBM's OS/2. Both firms struggled to take Smalltalk mainstream due to Smalltalk's substantial memory needs, limited run-time performance, and initial lack of supported connectivity to SQL-based relational database servers. While the high price of ParcPlace Smalltalk limited its market penetration to mid-sized and large commercial organizations, the Digitalk products initially tried to reach a wider audience with a lower price. IBM initially supported the Digitalk product, but then entered the market with a Smalltalk product in 1995 called VisualAge/Smalltalk. Easel introduced Enfin at this time on Windows and OS/2. Enfin became far more popular in Europe, as IBM introduced it into IT shops before their development of IBM Smalltalk (later VisualAge). Enfin was later acquired by Cincom Systems, and is now sold under the name ObjectStudio, and is part of the Cincom Smalltalk product suite.