Dominoes and storyboards beyond `icons on strings´

Practically since graphic displays were first hooked to computers, the idea of representing computer programs by pictures has attracted researchers. Most proposals for visual programming languages have adhered to a set pattern: fixed pictures symbolizing program components, connected by lines or arrows symbolizing relationships between the program components. The author explores one alternative: representing a program through visual examples of the state of its execution. He presents to related techniques: dominoes, which replace the traditional icons as representations of operations; and storyboards, which replace iconic circuitry as the representation of program code. These have been implemented in Mondrian, a graphic editor extensible through programming by example