Embedding attribute grammars and their extensions using functional zippers

Abstract

Attribute grammars are a suitable formalism to express complex software language analysis and manipulation algorithms, which rely on multiple traversals of the underlying syntax tree. Attribute grammars have been extended with mechanisms such as reference, higher-order and circular attributes. Such extensions provide a powerful modular mechanism and allow the specification of complex computations. This paper studies an elegant and simple, zipper-based embedding of attribute grammars and their extensions as first class citizens. In this setting, language specifications are defined as a set of independent, off-the-shelf components that can easily be composed into a powerful, executable language processor. Techniques to describe automatic bidirectional transformations between grammars in this setting are also described. Several real examples of language specification and processing programs have been implemented.

Memoized zipper-based attribute grammars and their higher order extension

“…HOAGs are supported by our zipper-based embedding as shown in [26,27]. Next, we show a simple Let-In language whose scope rules exactly follow the Algol 68 AG.…”

“…In this paper we focus on the embedding of AGs in Haskell proposed in [26], which we revise in Section 2. This embedding ensures a notation that closely resembles AGs, and even though it relies on a simple navigation engine, it has shown sufficient expressive power to incorporate state-of-the-art extensions to the AG formalism such as the possibility of not only defining classical (first-order) attribute grammars but also Higher-Order Attribute Grammars (HOAGs) [36,26,27]. This elegant AG embedding, however, has a severe performance problem: it does not ensure that attributes are computed only once on a given node.…”

Composition of Languages Embedded in Scala

“…In particular, should the code then fail statically or dynamically? Zipper functions [52], [53] act like HASKELL by statically reporting such errors so long as they can be caught iteratively [54].…”

Memoized Zipper-Based Attribute Grammars

“…In this paper we focus on the embedding proposed in [15] for Haskell, which we revise in Section 2. This choice is motivated by the fact that this embedding ensures a notation that closely resembles AGs , and even if it relies on a simple navigation engine, it has shown sufficient expressive power to incorporate stateof-the-art extensions to the AG formalism such as the possibility of defining: i) higher-order attributes [20,26], ii) references [14], iii) circular attributes [15,21], and iv) bidirectional transformations [16].…”