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Smalltalk is an object-oriented, dynamically typed, reflective programming language. It was created as the language to underpin 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 Xerox PARC by Alan Kay, Dan Ingalls, Adele Goldberg, Ted Kaehler, Scott Wallace, and others during the 1970s, influenced by Lisp, Logo, Sketchpad and Simula. The language was first generally released as Smalltalk-80 and has been widely used since. 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. HistoryThere are a large number of Smalltalk variants, as there are with many computer languages. 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 by a group of researchers led by Alan Kay at Xerox Palo Alto Research Center (PARC); Alan Kay designed most of the early Smalltalk versions, which Dan Ingalls implemented. The first version, known as Smalltalk-71, was created 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 actually used for research work is now known as 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 tools now familiar including a class library code browser/editor. Smalltalk-80 added metaclasses, to help maintain the "everything is an object" (except 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 of creating 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 companies (Hewlett-Packard, Apple Computer, Tektronix, and DEC) and universities (UC Berkeley) for "peer review" and implementation on their platforms. Later (in 1983) a general availability implementation, known as 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 2002 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 emphasized Intel-based PCs that were running either Microsoft Windows or IBM's OS/2. Both companies, however, struggled to take Smalltalk mainstream due to Smalltalk's substantial memory footprint, limited run-time performance, and initial lack of supported connectivity to SQL-based relational database servers. While the high price point of the 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 point. IBM having initially supported the Digitalk product 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 much more popular in Europe, as IBM introduced it into IT shops prior to 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. In 1995, ParcPlace and Digitalk merged into ParcPlace-Digitalk and then rebranded in 1997 as ObjectShare, located in Irvine, CA. ObjectShare (NASDAQ: OBJS) was traded publicly until 1999, when it was delisted and dissolved. The merged company never managed to find an effective response to Java in terms of market positions and by 1997 its owners were looking to sell the business. In 1999, Seagull Software acquired the Java development lab of ObjectShare (original Smalltalk/V, Visual Smalltalk development team), and still owns VisualSmalltalk, although worldwide distribution rights for the Smalltalk product remained with ObjectShare. VisualWorks was sold to Cincom and is now part of Cincom Smalltalk. Cincom has backed Smalltalk quite strongly, putting out multiple new releases of VisualWorks and ObjectStudio each year since 1999. Cincom, Gemstone and Object Arts, plus other vendors continue to sell Smalltalk environments, IBM has 'end of life'd VisualAge Smalltalk having in the late 1990s decided to back Java and it is, as of 2006, supported by Instantiations, Inc. which has renamed the product VASmalltalk and released a new version. The open Squeak implementation has an active community of developers, including many of the original Smalltalk community, and has recently been used to provide the Etoys environment on the OLPC project and the virtual worlds environment Croquet Project. GNU Smalltalk is a free software implementation of a derivative of Smalltalk-80 from the GNU project. A significant development, that has spread across all current Smalltalk environments, is the increasing usage of the Seaside and AIDA/Web web frameworks to simplify the building of complex web applications. Article source: http://en.wikipedia.org/wiki/Smalltalk Go back to Programming Articles home page
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