LispKit

• Squeak3.9 - Released 8 Dec 2006.
• Bleeding edge - Hardly runnable, full of bugs! For developers only.
• Squeak3.10-alpha - This is the current moving target of 3.10.
• Squeak3.8 - Released 25 May 2005.
• Only extensions, no changes - Code extensions but no changes in existing code.
• MIT - The MIT license is like BSD without the advertising clause. As free as it gets, suitable for cross Smalltalk 100% reuse. The recommended license for Squeak since the 4.0 release.
• Stable - Useable by all. Bugs are rare.
• Beta - Useable but still not stable, probably has bugs.
• SqueakL + MIT - Dual licensed under both SqueakL and MIT. This enables both base Squeak inclusion and 100% reuse. Recommended prior to 4.0.

ULisp: low-level refactoring for an average 30% speed-up