Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Wikipedia.


The pioneering object-oriented programming system developed in 1972 by the Software Concepts Group, led by Alan Kay, at Xerox PARC between 1971 and 1983. It includes a language, a programming environment, and an extensive object library.

Smalltalk took the concepts of class and message from Simula-67 and made them all-pervasive. Innovations included the bitmap display, windowing system, and use of a mouse.

The syntax is very simple. The fundamental construction is to send a message to an object:

object message

or with extra parameters

object message: param1 secondArg: param2 .. nthArg: paramN

where "secondArg:" etc. are considered to be part of the message name.

Five pseudo-variables are defined: "self", "super", "nil", "true", "false". "self" is the receiver of the current message. "super" is used to delegate processing of a message to the superclass of the receiver. "nil" is a reference to "nothing" (an instance of UndefinedObject). All variables initially contain a reference to nil. "true" and "false" are Booleans.

In Smalltalk, any message can be sent to any object. The recipient object itself decides (based on the message name, also called the "message selector") how to respond to the message. Because of that, the multiple inheritance system included in the early versions of Smalltalk-80 appeared to be unused in practice. All modern implementations have single inheritance, so each class can have at most one superclass.

Early implementations were interpreted but all modern ones use dynamic translation (JIT).

Early versions were Smalltalk-72, Smalltalk-74, Smalltalk-76 (inheritance taken from Simula, and concurrency), and Smalltalk-78, Smalltalk-80. Other versions include Little Smalltalk, Smalltalk/V, Kamin's interpreters. Current versions are VisualWorks, Squeak, VisualAge, Dolphin Smalltalk, Object Studio, GNU Smalltalk.

See also: International Smalltalk Association.

UIUC Smalltalk archive. FAQ.

Usenet newsgroup: news:comp.lang.smalltalk.

["The Smalltalk-76 Programming System Design and Implementation", D.H. Ingalls, 5th POPL, ACM 1978, pp. 9-16].
This article is provided by FOLDOC - Free Online Dictionary of Computing (


An operating system and object-oriented programming language that was developed at Xerox PARC. As an integrated environment, it eliminates the distinction between programming language and operating system. It also allows its user interface and behavior to be customized.

Smalltalk was the first object-oriented programming language to become popular. It was originally used to create prototypes of simpler programming languages and the graphical interfaces that are so popular today. Smalltalk was first run on Xerox's Alto computer, which was designed for it. In 1980, Smalltalk-80 was licensed to Tektronix, Apple, HP and TI for internal use. The first commercial release of Smalltalk was Methods from Digitalk in 1983, which later evolved into Visual Smalltalk. In 1997, Smalltalk became an ANSI standard (X3J20). See VisualWorks, Visual Smalltalk, VisualAge and Alto.
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
SmallTalk Daily Activities is a direct selection communicator program designed for use by individuals with aphasia or speech or communication disabilities.
We make cautious introductions, some "How-do-you-know-Zefrey?" smalltalk. The cops are pretty curious.
"My big worry about the jungle was meeting people, socialising and making smalltalk. Icoulddeal with the older people, not the younger ones."
Machine Language, Ferranti Autocode, Fortran II, IV, APL, PL1, C, Smalltalk, Lisp, C++, Python.
The concept is usually found in dynamic languages, such as Smalltalk [3], Lisp [7, 1], and Self [8].
Lingraphica, maker of the Lingraphica speech-generating device for aphasia, has released the "SmallTalk" mobile accessory.
Title: Specialist speech and language therapist and director of SmallTalk.
Alan Kay, inventor of Smalltalk, which was the inspiration and technical basis for the Macintosh and subsequent windowing-based systems, stated in 1971: "The best way to predict the future is to invent it."
As Alan Kay, one of the inventors of the Smalltalk programming language and one of the fathers of the idea of object-oriented programming, said, "Perspective is worth 80 IQ points."