Ralf Lämmel, Joost Visser. Design patterns for functional strategic programming. In Bernd Fischer, Eelco Visser, editors, Proceedings of the 2002 ACM SIGPLAN Workshop on Rule-Based Programming, Pittsburgh, Pennsylvania, USA, 2002. pages 1-14, ACM, 2002.
We believe that design patterns can be an effective means of consolidating and communicating program construction expertise for functional programming, just as they have proven to be in object-oriented programming. The emergence of combinator libraries that develop a specific domain or programming idiom has intensified, rather than reduced, the need for design patterns. In previous work, we introduced the fundamentals and a supporting combinator library for functional strategic programming. This is an idiom for (general purpose) generic programming based on the notion of a functional strategy: a first-class generic function that can not only be applied to terms of any type, but which also allows generic traversal into subterms and can be customised with type-specific behaviour. This paper seeks to provide practising functional programmers with pragmatic guidance in crafting their own generic programs using functional strategies. To this end, we propose a novel description format for functional design patterns, and we initiate a catalogue of strategy design patterns. These design patterns aim at consolidating strategic programming expertise in accessible form.