Revised Report on the Algorithmic Language Algol 60

Wijngaarden, A. van; Mailloux, B. J.; Peck, J. E. L.; Koster, C. H. A.; Sintzoff, Michel; Lindsey, C. H.; Meertens, L.G.L.T.; Fisker, R. G.

doi:10.1007/978-1-4612-4118-8_2

Cited by 126 publications

(57 citation statements)

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“…One of the rst things most programmers learn is how to \declare" a new assignable local variable, and facilities to support this have been available in programming languages for over thirty years (Naur et al, 1963). It might be thought that there would by now be a satisfactory semantic interpretation for so fundamental and apparently elementary a mechanism.…”

mentioning

confidence: 99%

Parametricity and Local Variables

O’Hearn¹,

Tennent²

1997

Algol-Like Languages

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We propose that the phenomenon of local state may be understood in terms of Strachey's concept of parametric (i.e., uniform) polymorphism. The intuitive basis for our proposal is the following analogy: a non-local procedure is independent of locally-declared variables in the same way that a parametrically polymorphic function is independent of types to which it is instantiated.A connection between parametricity and representational abstraction was rst suggested by J.C. Reynolds. Reynolds used logical relations to formalize this connection in languages with type variables and user-de ned types. We use relational parametricity to construct a model for an Algol-like language in which interactions between local and non-local entities satisfy certain relational criteria. Reasoning about local variables essentially involves proving properties of polymorphic functions. The new model supports straightforward validations of all the test equivalences that have been proposed in the literature for local-variable semantics, and encompasses standard methods of reasoning about data representations. It is not known whether our techniques yield fully abstract semantics. A model based on partial equivalence relations on the natural numbers is also brie y examined.

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confidence: 99%

Parametricity and Local Variables

O’Hearn¹,

Tennent²

1997

Algol-Like Languages

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“…programming languages). In the simplest case, such grammars are written in Backus-Naur Form [36,24]. Examples of more sophisticated grammar formalisms for formal languages -called parser generators -include Yacc [21] and GNU bison 1 .…”

Section: Parser Generatorsmentioning

confidence: 99%

A Principled Approach to Grammars for Controlled Natural Languages and Predictive Editors

Kuhn

2013

J of Log Lang and Inf

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Controlled natural languages (CNL) with a direct mapping to formal logic have been proposed to improve the usability of knowledge representation systems, query interfaces, and formal specifications. Predictive editors are a popular approach to solve the problem that CNLs are easy to read but hard to write. Such predictive editors need to be able to "look ahead" in order to show all possible continuations of a given unfinished sentence. Such lookahead features, however, are difficult to implement in a satisfying way with existing grammar frameworks, especially if the CNL supports complex nonlocal structures such as anaphoric references. Here, methods and algorithms are presented for a new grammar notation called Codeco, which is specifically designed for controlled natural languages and predictive editors. A parsing approach for Codeco based on an extended chart parsing algorithm is presented. A large subset of Attempto Controlled English (ACE) has been represented in Codeco. Evaluation of this grammar and the parser implementation shows that the approach is practical, adequate and efficient.

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“…More sophisticated languages, beginning with Algol V. 60 [10], embodied concepts for algorithm development and organization principles, e.g. bottom-up, top-down and recursive program development, modularity, types, higher order functions, automatic memory management and much more.…”

Section: (A) Programming Languagesmentioning

confidence: 99%

Programs=data=first-class citizens in a computational world

Jones

Simonsen

2012

Phil. Trans. R. Soc. A.

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From a programming perspective, Alan Turing's epochal 1936 paper on computable functions introduced several new concepts, including what is today known as self-interpreters and programs as data , and invented a great many now-common programming techniques. We begin by reviewing Turing's contribution from a programming perspective; and then systematize and mention some of the many ways that later developments in models of computation (MOCs) have interacted with computability theory and programming language research. Next, we describe the ‘blob’ MOC: a recent stored-program computational model without pointers . In the blob model, programs are truly first-class citizens , capable of being automatically compiled, or interpreted, or executed directly. Further, the blob model appears closer to being physically realizable than earlier computation models. In part, this is due to strong finiteness owing to early binding in the program; and a strong adjacency property : the active instruction is always adjacent to the piece of data on which it operates. The model is Turing complete in a strong sense: a universal interpretation algorithm exists that is able to run any program in a natural way and without arcane data encodings. Next, some of the best known among the numerous existing MOCs are described, and we develop a list of traits an ‘ideal’ MOC should possess from our perspective. We make no attempt to consider all models put forth since Turing's 1936 paper, and the selection of models covered concerns only models with discrete, atomic computation steps. The next step is to classify the selected models by qualitative rather than quantitative features. Finally, we describe how the blob model differs from an ‘ideal’ MOC, and identify some natural next steps to achieve such a model.

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Revised Report on the Algorithmic Language Algol 60

Cited by 126 publications

References 0 publications

Parametricity and Local Variables

Parametricity and Local Variables

A Principled Approach to Grammars for Controlled Natural Languages and Predictive Editors

Programs=data=first-class citizens in a computational world

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