Self for Mac

From OpenGL:

Self is an object-oriented programming language and associated programming environment. It is close in spirit and semantics to Smalltalk:
* It is a pure object-oriented language, i.e., everything in the computational domain of Self is an object.
* Its syntax borrows heavily from Smalltalk.
* As in Smalltalk, variables are of unrestricted type.
* It uses blocks - objects which behave like procedures - to implement control structures.
* Programs are constructed incrementally within the programming environment. An exploratory style is encouraged. However, it differs from Smalltalk in several important respects. The principal force guiding the design of Self was the desire for simplicity and concreteness. This force is manifested thus:
* Self is considerably simpler than Smalltalk in syntax and semantics. More of the basic facilities in the Self system are implemented in Self, itself.
* Self has no classes. Instead a more direct object-based inheritance mechanism is provided. The programming environment facilitates direct manipulation, in which the programmer communicates with objects directly (or appears to), rather than applying "tools" to effect changes.