Extensible Pattern Matching for Extensible Languages
đź“ś Abstract
We describe a novel approach to adding flexible pattern matching facilities to programming languages, based on a combination of pattern matching and constructor classes. By classifying and abstracting patterns over datatype constructors, this approach provides pattern matching libraries with the same conciseness and ease-of-use as regular pattern matching, while simultaneously being extensible in a type-safe manner. Our technique can be directly applied to both functional and object-oriented languages and bridges the gap between open polymorphic variants and closed algebraic datatypes. We illustrate our technique by extending a small functional language with pattern matching facilities.
✨ Summary
The paper “Extensible Pattern Matching for Extensible Languages” by Daan Leijen and Erik Meijer introduces a method to integrate flexible pattern matching capabilities into programming languages. This is achieved through a new approach that combines pattern matching with constructor classes, offering a concise, user-friendly yet extensible and type-safe pattern matching framework. This approach is adaptable for both functional and object-oriented languages, effectively bridging open polymorphic variants and closed algebraic datatypes. The technique is exemplified by the implementation in a small functional language.
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