Smalltalk and generic concepts in programming languages

Abstract

Early generic concepts in programming languages were mixed-type arithmetic (e.g., “+” used with any combination of fixed-and floating-point numbers) and “print” functions which could be applied to any of a language's objects. Generic concepts reduce the number of terms which must be remembered and permit considerable condensation of language design. Three different paths in the development of generic-concept languages have been followed by APL, Algol 68, and object-oriented languages such as SIMULA 67 and Smalltalk. APL was the earliest and one of the most interesting applications of generic-concept methods, but now makes the weakest use of these ideas. My talk will use slides and movies to show how the message-object programming system Smalltalk makes use of generic concepts embedded in class descriptions to give rise to a wide variety of simply programmed dynamic simulations including graphic animation, music synthesis, document layout and retrieval, and APL-like calculation features. Many of these systems have been brought to life by child and adult novice programmers. A short list of references is given for those wishing more introductory information about Smalltalk.