Smalltalk
Smalltalk is a purely object-oriented, dynamically typed programming language and integrated development environment developed at Xerox PARC in the 1970s, which coined the term 'object-oriented programming' and pioneered the graphical,…
Definition
Smalltalk is a purely object-oriented, dynamically typed programming language and integrated development environment developed at Xerox PARC in the 1970s, which coined the term 'object-oriented programming' and pioneered the graphical, live-coding IDE.
Overview
Smalltalk was developed at Xerox's Palo Alto Research Center (PARC) in the 1970s, led by Alan Kay along with Dan Ingalls, Adele Goldberg, and others, as part of a broader vision of personal computing and the 'Dynabook' concept — a portable, dynamic-media device meant to make computing accessible and expressive, particularly for children and non-specialist creators. Smalltalk was designed to be uniformly and purely object-oriented: every value, including numbers, classes, and even the compiler itself, is an object that responds to messages, and all computation happens through objects sending messages to other objects — a more radical and consistent application of object orientation than Simula's, which had introduced classes and objects but retained more conventional procedural elements. Beyond the language itself, Smalltalk's environment was arguably as influential as its syntax: it was one of the first systems to feature a fully graphical, windowed, mouse-driven interface with overlapping windows, menus, and icons — technology later commercialized in the Xerox Alto and Star workstations and which directly inspired the Apple Macintosh and, through it, essentially all modern graphical user interfaces. Smalltalk pioneered 'live' or 'image-based' programming, where the entire running state of the system — all objects, classes, and their live instances — persists in a saved 'image' that can be inspected, modified, and resumed, blurring the line between editing and running a program, and it introduced the Model-View-Controller (MVC) architectural pattern still widely used in application and web frameworks today. Smalltalk-80, released in 1980, was the version broadly published and licensed to other companies, spawning commercial and open implementations (VisualWorks, Squeak, Pharo, GNU Smalltalk) that remain in active, if niche, use. While Smalltalk itself never achieved mass-market industrial adoption on the scale of Java or C++, its influence is exceptionally broad: the term 'object-oriented programming' itself originates with Kay's Smalltalk work, and its ideas around dynamic dispatch, reflection, the MVC pattern, and live development environments directly shaped Objective-C, Ruby, Python, and the design of modern IDEs and debuggers.
Key Features
- Purely object-oriented — everything, including numbers and classes, is an object responding to messages
- Dynamically typed with message-passing as the sole mechanism of computation
- Image-based, live development environment where running system state persists and is directly editable
- One of the first systems with a graphical, windowed, mouse-driven user interface
- Introduced the Model-View-Controller (MVC) architectural pattern
- Coined the term 'object-oriented programming'
- Reflective — the language and its own tools (compiler, debugger, browser) are themselves Smalltalk objects