|Designed by||Alan Kay, Dan Ingalls, Adele Goldberg|
|Developers||The Squeak Community|
6.0-22104 / 6 June 2022
|OS||Cross-platform: Unix-like, macOS, iOS, Windows, more|
|Filename extensions||.image, .changes, .sources, .st|
|Croquet, Newspeak (programming language), Pharo|
|Smalltalk, Lisp, Logo; Sketchpad, Simula; Self|
|Etoys, Tweak, Croquet, Scratch|
Squeak is an object-oriented, class-based, and reflective programming language. It was derived from Smalltalk-80 by a group that included some of Smalltalk-80's original developers, initially at Apple Computer, then at Walt Disney Imagineering, where it was intended for use in internal Disney projects. The group would later go on to be supported by HP labs, SAP, and most recently, Y Combinator.
Squeak runs on a virtual machine (VM), allowing for a high degree of portability. The Squeak system includes code for generating a new version of the VM on which it runs, along with a VM simulator written in Squeak.
Dan Ingalls, an important contributor to the Squeak project, wrote the paper upon which Squeak is built, and constructed the architecture for five generations of the Smalltalk language.
Alan Kay is an important contributor to the Squeak project, and Squeak incorporates many elements of his proposed Dynabook concept.
Squeak includes four user interface frameworks:
Many Squeak contributors collaborate on Open Cobalt, a free and open source virtual world browser and construction toolkit built on Squeak.
The first version of Scratch was implemented in Squeak.
OpenQwaq, a virtual conferencing and collaboration system, is based on Squeak.
Squeak is also used in the Nintendo ES operating system
Squeak 4.0 and later may be downloaded at no cost, including source code, as a prebuilt virtual machine image licensed under the MIT License, with the exception of some of the original Apple code, which is governed by the Apache License.
Squeak was originally released by Apple under its own Squeak License. While source code was available and modification permitted, the Squeak License contained an indemnity clause that prevented it from qualifying as true free and open-source software.
In 2006, Apple relicensed Squeak twice. First, in May, Apple used its own Apple Public Source License, which satisfies the Free Software Foundation's concept of a Free Software License and has attained official approval from the Open Source Initiative as an Open Source License. However, The Apple Public Source License fails to conform to the Debian Free Software Guidelines. To enable inclusion of Etoys in the One Laptop Per Child project, a second relicensing was undertaken using the Apache License. At this point, an effort was also made to address the issue of code contributed by members of the Squeak community, which it was not in Apple's power to unilaterally relicense.
For each contribution made under the Squeak License since 1996, a relicensing statement was obtained authorizing distribution under the MIT license, and finally in March 2010, the end result was released as Squeak 4.0, now under combined MIT and Apache licenses.
The Squeak virtual machine is a family of virtual machines (VMs) used in Smalltalk programming language implementations. They are an essential part of any Smalltalk implementation. All are open-source software. The current VM is a high performance dynamic translation system. The relevant code is maintained in the OpenSmalltalk/opensmalltalk-vm repository on GitHub.