Typed Transformations of Typed Grammars: The Left Corner Transform

Baars, Arthur I.; Swierstra, S. Doaitse; Viera, Marcos

doi:10.1016/j.entcs.2010.08.031

Cited by 15 publications

(26 citation statements)

References 5 publications

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“…Attribute grammars have been related to functional parsing actions [40]. In the context of parsing combinators in Haskell [41], Swierstra and coauthors have defined typed transformations of semantic actions [25], including left-recursion elimination via the left-corner transformation [24]. A major challenge they solve in their work is to accommodate grammar transformations in the Haskell type system, which is orthogonal to the aims of the present paper.…”

Section: Related Workmentioning

confidence: 99%

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On the semantics of parsing actions

Thielecke

2014

Science of Computer Programming

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Parsers, whether constructed by hand or automatically via a parser generator tool, typically need to compute some useful semantic information in addition to the purely syntactic analysis of their input. Semantic actions may be added to parsing code by hand, or the parser generator may have its own syntax for annotating grammar rules with semantic actions. In this paper, we take a functional programming view of such actions. We use concepts from the semantics of mostly functional programming languages and adapt them to give meaning to the actions of the parser. Specifically, the semantics is inspired by the categorical semantics of lambda calculi and the use of premonoidal categories for the semantics of effects in programming languages. This framework is then applied to our leading example, the transformation of grammars to eliminate left recursion. The syntactic transformation of leftrecursion elimination leads to a corresponding semantic transformation of the actions for the grammar. We prove the semantic transformation correct and relate it to continuation passing style, a widely studied transformation in lambda calculi and functional programming. As an idealization of the input language of parser generators, we define a call-by-value calculus with first-order functions and a type-and-effect system where the effects are given by sequences of grammar symbols. The account of left-recursion elimination is then extended to this calculus.

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Section: Related Workmentioning

confidence: 99%

“…The left-corner transformation has been implemented and investigated by several researchers in the context of parsing combinators in functional programming [25,26,27].…”

Section: The Left-corner Transformation and Continuation Passingmentioning

confidence: 99%

On the semantics of parsing actions

Thielecke

2014

Science of Computer Programming

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“…However, this higher-order approach results in much of the grammar being trapped under lambdas, thereby prohibiting useful analyses and transformations which can be critical for performance or even termination (for example, the recent left-corner transform for typed grammars [1]) [12,19]. Paterson proposed the arrow notation as an alternative approach that allows such analyses and transformations for arrow combinators [14].…”

Section: Related Workmentioning

confidence: 99%

“…f [4][5][6] are defined in the same way as f [1][2][3] , so the parsing engine ends up using the 4-box to bind p 2 , and the 5,6-box to calculate the predicate (p 2 − p 1 = x). If this evaluates to true, the engine uses the 5,6 box to calculate the final value, (), of the successful parse; otherwise, this run of the parse fails.…”

Section: Coroutines By Examplementioning

confidence: 99%

A New Method for Dependent Parsing

Jim

Mandelbaum

2011

Programming Languages and Systems

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Abstract. Dependent grammars extend context-free grammars by allowing semantic values to be bound to variables and used to constrain parsing. Dependent grammars can cleanly specify common features that cannot be handled by context-free grammars, such as length fields in data formats and significant indentation in programming languages. Few parser generators support dependent parsing, however. To address this shortcoming, we have developed a new method for implementing dependent parsers by extending existing parsing algorithms. Our method proposes a point-free language of dependent grammars, which we believe closely corresponds to existing context-free parsing algorithms, and gives a novel transformation from conventional dependent grammars to point-free ones.To validate our technique, we have specified the semantics of both source and target dependent grammar languages, and proven our transformation sound and complete with respect to those semantics. Furthermore, we have empirically validated the suitability of our point-free language by adapting four parsing engines to support it: an Earley parsing engine; a GLR parsing engine; memoizing, arrow-style parser combinators; and PEG parser combinators.

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“…We use a representation of grammars as typed abstract syntax [7] based on the use of Generalized Algebraic Data Types [54]. The idea is to indirectly refer to non-terminals via references encoded as types.…”

Section: Grammar Representationmentioning

confidence: 99%