Abstract

. Functional animation encourages a highly modular programming style, by supplying a set of arbitrarily composable functions for building up animations. In contrast, libraries for sprite-based display impose rigid structure, in order to allow acceleration by hardware and low level software. This paper presents a method to bridge the gap between functional specification and stateful, sprite-based presentation of animation. The method's correctness is proved informally by derivation from a simple non-effective specification, exploiting algebraic properties of the animation data types that are made explicit in the functional approach. We have implemented this method in the Fran system, which is freely available. 1 Introduction The functional approach to animation offers considerable flexibility and modularity [1, 7]. Animations are first-class values---elements of a data type consisting of a set of constants and combining operators. The data type allows great flexibility in co...

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