Black A.P. et al. Pharo by Example

Authors: Andrew P. Black, Stéphane Ducasse, Oscar Nierstrasz, Damien Pollet.Square Bracket Associates (Switzerland), 2009. — 352 p.Pharo is a modern, open-source, fully-featured implementation of the Smalltalk programming language and environment. Pharo is derived from Squeak1, a re-implementation of the classic Smalltalk-80 system. Whereas Squeak was developed mainly as a platform for developing experimental educational software, Pharo strives to offer a lean, open-source platform for professional software development, and a robust and stable platform for research and development into dynamic languages and environments. Pharo serves as the reference implementation for the Seaside web development framework.
Pharo resolves some licensing issues with Squeak. Unlike previous versions of Squeak, the Pharo core contains only code that has been contributed under the MIT license. The Pharo project started in March 2008 as a fork of Squeak 3.9, and the first 1.0 beta version was released on July 31, 2009. Although Pharo removes many packages from Squeak, it also includes numerous features that are optional in Squeak. For example, true type fonts are bundled into Pharo. Pharo also includes support for true block closures.
The user interfaces has been simplified and revised. Pharo is highly portable — even its virtual machine is written entirely in Smalltalk, making it easy to debug, analyze, and change. Pharo is the vehicle for a wide range of innovative projects from multimedia applications and educational platforms to commercial web development environments.