Smalltalk

Smalltalk is an object-oriented programming language and family of languages. It is notable among object-oriented languages in that "everything is an object"; even function invocation is achieved by way of objects called "messages". Because of this, and that one of its creators is Alan Kay (the originator of the term "object-oriented programming"), it is considered by some to be one of the definitive examples of the paradigm.

The original Smalltalk language, Smalltalk-80, is no longer in mainstream use, but several descendants carry on its legacy with small but dedicated communities of developers and users. Among these are Squeak, whose Morphic UI toolkit was the source of some of the ideas in Factor's UI, and Pharo, a fork of Squeak which is likely the most popular and advanced Smalltalk environment in the present day.