Tool by Alan Kay, Dan Ingalls, Adele Goldberg, Learning Research Group of Xerox PARC (1972 – present)

A programming language and in-context development environment with powerful built-in tools like a class browser, object inspector, and debugger.

The message is the most fundamental language construct in Smalltalk. Even control structures are implemented as message sends. — Wikipedia

The late-bound, message-based interfaces of objects provide strong interposability properties: clients remain oblivious of the specific implementation they are talking to. In turn, this simplifies the customisation, extension or replacement of parts of a system, all of which can be rendered as interposition of a different object on the same client. — Stephen Kell, The operating system: should there be one? (2013)


  • suggesters: geoffreylitt, jryans
  • curators: jryans