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Grammatical Framework: A TypeTheoretical Grammar Formalism
, 2003
"... Grammatical Framework (GF) is a specialpurpose functional language for defining grammars. It uses a Logical Framework (LF) for a description of abstract syntax, and adds to this a notation for defining concrete syntax. GF grammars themselves are purely declarative, but can be used both for lineariz ..."
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Cited by 77 (19 self)
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Grammatical Framework (GF) is a specialpurpose functional language for defining grammars. It uses a Logical Framework (LF) for a description of abstract syntax, and adds to this a notation for defining concrete syntax. GF grammars themselves are purely declarative, but can be used both for linearizing syntax trees and parsing strings. GF can describe both formal and natural languages. The key notion of this description is a grammatical object, which is not just a string, but a record that contains all information on inflection and inherent grammatical features such as number and gender in natural languages, or precedence in formal languages. Grammatical objects have a type system, which helps to eliminate runtime errors in language processing. In the same way as an LF, GF uses...
Gast: Generic Automated Software Testing
 The 14th International Workshop on the Implementation of Functional Languages, IFL’02, Selected Papers, volume 2670 of LNCS
, 2002
"... Software testing is a laborintensive and hence expensive, yet heavily used technique to control quality. In this paper we introduce Gast, a fully automatic testtool. Properties from first order logic can be expressed in the system, Gast automatically generates appropriate testdata, evaluates ..."
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Cited by 43 (17 self)
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Software testing is a laborintensive and hence expensive, yet heavily used technique to control quality. In this paper we introduce Gast, a fully automatic testtool. Properties from first order logic can be expressed in the system, Gast automatically generates appropriate testdata, evaluates the property for these values, and analyzes the testresults. In this way it becomes easier and cheaper to test software components. The distinguishing property of our system is that the testdata are generated in a systematic and generic way using generic programming techniques. This implies that there is no need for the user to indicate how data should be generated. Moreover, duplicated tests are avoided and for finite domains Gast is able to proof a property by testing it for all possible values. As an important sidee#ect, it also encourages stating formal properties of the software.
Functional morphology
 Proceedings of the Ninth ACM SIGPLAN International Conference of Functional Programming, Snowbird
, 2004
"... This paper presents a methodology for implementing natural language morphology in the functional language Haskell. The main idea behind is simple: instead of working with untyped regular expressions, which is the state of the art of morphology in computational linguistics, we use finite functions ov ..."
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Cited by 28 (13 self)
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This paper presents a methodology for implementing natural language morphology in the functional language Haskell. The main idea behind is simple: instead of working with untyped regular expressions, which is the state of the art of morphology in computational linguistics, we use finite functions over hereditarily finite algebraic datatypes. The definitions of these datatypes and functions are the languagedependent part of the morphology. The languageindependent part consists of an untyped dictionary format which is used for synthesis of word forms, and a decorated trie, which is used for analysis. Functional Morphology builds on ideas introduced by Huet in his computational linguistics toolkit Zen, which he has used to implement the morphology of Sanskrit. The goal has been to make it easy for linguists, who are not trained as functional programmers, to apply the ideas to new languages. As a proof of the productivity of the
Arrows, like monads, are monoids
 Proc. of 22nd Ann. Conf. on Mathematical Foundations of Programming Semantics, MFPS XXII, v. 158 of Electron. Notes in Theoret. Comput. Sci
, 2006
"... Monads are by now wellestablished as programming construct in functional languages. Recently, the notion of “Arrow ” was introduced by Hughes as an extension, not with one, but with two type parameters. At first, these Arrows may look somewhat arbitrary. Here we show that they are categorically fai ..."
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Cited by 14 (1 self)
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Monads are by now wellestablished as programming construct in functional languages. Recently, the notion of “Arrow ” was introduced by Hughes as an extension, not with one, but with two type parameters. At first, these Arrows may look somewhat arbitrary. Here we show that they are categorically fairly civilised, by showing that they correspond to monoids in suitable subcategories of bifunctors C op ×C → C. This shows that, at a suitable level of abstraction, arrows are like monads — which are monoids in categories of functors C → C. Freyd categories have been introduced by Power and Robinson to model computational effects, well before Hughes ’ Arrows appeared. It is often claimed (informally) that Arrows are simply Freyd categories. We shall make this claim precise by showing how monoids in categories of bifunctors exactly correspond to Freyd categories.
On the Anonymity of Timed Pool Mixes
 In Proceedings of the Workshop on Privacy and Anonymity Issues in Networked and Distributed Systems
, 2003
"... This paper presents a method for calculating the anonymity of a timed pool mix. Thus we are able to compare it to a threshold pool mix, and any future mixes that might be developed. Although we are only able to compute the anonymity of a timed pool mix after some speci c number of rounds, this is a ..."
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Cited by 13 (3 self)
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This paper presents a method for calculating the anonymity of a timed pool mix. Thus we are able to compare it to a threshold pool mix, and any future mixes that might be developed. Although we are only able to compute the anonymity of a timed pool mix after some speci c number of rounds, this is a practical approximation to the real anonymity.
A Recursive do for Haskell
, 2002
"... Certain programs making use of monads need to perform recursion over the values of monadic actions. Although the donotation of Haskell provides a convenient framework for monadic programming, it lacks the generality to support such recursive bindings. In this paper, we describe an enhanced translat ..."
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Cited by 11 (1 self)
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Certain programs making use of monads need to perform recursion over the values of monadic actions. Although the donotation of Haskell provides a convenient framework for monadic programming, it lacks the generality to support such recursive bindings. In this paper, we describe an enhanced translation schema for the donotation and its integration into Haskell. The new translation allows variables to be bound recursively, provided the underlying monad comes equipped with an appropriate fixedpoint operator.
Programming With Types
 CORNELL UNIVERSITY
, 2002
"... Runtime type analysis is an increasingly important linguistic mechanism in modern programming languages. Language runtime systems use it to implement services such as accurate garbage collection, serialization, cloning and structural equality. Component frameworks rely on it to provide reflection m ..."
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Cited by 11 (1 self)
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Runtime type analysis is an increasingly important linguistic mechanism in modern programming languages. Language runtime systems use it to implement services such as accurate garbage collection, serialization, cloning and structural equality. Component frameworks rely on it to provide reflection mechanisms so they may discover and interact with program interfaces dynamically. Runtime type analysis is also crucial for large, distributed systems that must be dynamically extended, because it allows those systems to check program invariants when new code and new forms of data are added. Finally, many generic userlevel algorithms for iteration, pattern matching, and unification can be defined through type analysis mechanisms. However, existing frameworks for runtime type analysis were designed for simple type systems. They do not scale well to the sophisticated type systems of modern and nextgeneration programming languages that include complex constructs such as firstclass abstract types, recursive types, objects, and type parameterization. In addition, facilities to support type analysis often require complicated
Lazy Dynamic Input/Output in the lazy functional language Clean
 The 14th International Workshop on the Implementation of Functional Languages, IFL’02, Selected Papers, volume 2670 of LNCS
, 2002
"... The new release of Clean oers a hybrid type system with both static and dynamic typing. Any common static Clean expression can in principle be converted into a dynamic expression (called a "dynamic "), and backwards. The type of the dynamic (an encoding of the original static type) can be ..."
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Cited by 10 (9 self)
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The new release of Clean oers a hybrid type system with both static and dynamic typing. Any common static Clean expression can in principle be converted into a dynamic expression (called a "dynamic "), and backwards. The type of the dynamic (an encoding of the original static type) can be checked at runtime via a special pattern match after which the dynamic expression can be evaluated as eciently as usual. Clean furthermore oers "dynamic I/O": any application can read in a dynamic that is stored by some other application. Such a dynamic can contain unevaluated functions (closures) that are unknown in the receiving application. The receiving application therefore has to be extended with these function de nitions. This is not trivial because Clean uses compiled code and is not an interpreted language that uses some byte code. A running Clean application therefore communicates with a dynamic linker that is able to add the missing binary code to the running application. So, dynamics can be used to realize plugins and mobile code in a type safe way without loss of eciency in the resulting code. In this paper we explain the implementation of dynamic I/O. Dynamics are written in such a way that internal sharing is preserved when a dynamic is read. Dynamics are read in very lazily in phases: rst its type is checked, and only if the evaluation is demanded, the dynamic expression is reconstructed and the new code is linked in. Dynamics can become quite complicated: they can contain sharing, they can be cyclic, they can even refer to other dynamics, and they may be distributed over a computer network. We have managed to completely hide the internal storage structure for the user by separating the storage of dynamics in system space and user space. For the user a dynamic o...
Semantics of fixIO
, 2001
"... Recent work on recursion over the values of monadic actions resulted in the introduction of a family of fixed point operators, one for each di#erent kind of monadic e#ect. In the context of Haskell, the function fixIO is the corresponding operator for the IO monad. Unfortunately, both the IO monad a ..."
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Cited by 6 (3 self)
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Recent work on recursion over the values of monadic actions resulted in the introduction of a family of fixed point operators, one for each di#erent kind of monadic e#ect. In the context of Haskell, the function fixIO is the corresponding operator for the IO monad. Unfortunately, both the IO monad and fixIO are language primitives in Haskell, i.e. they can not be defined within the language itself. Therefore, any attempt to formally reason about fixIO is futile without a precise semantics for computations in the IO monad. Quite recently, Peyton Jones introduced an operational semantics based on observable transitions as a method for reasoning about I/O in Haskell. Building on this work, we show how one can model fixIO as well, and we argue that it indeed belongs to the family of fixed point operators that enable monadic value recursion.
Modular Lazy Search for Constraint Satisfaction Problems
 JOURNAL OF FUNCTIONAL PROGRAMMING
, 2001
"... We describe a unified, lazy, declarative framework for solving constraint satisfaction problems, an important subclass of combinatorial search problems. These problems are both practically significant and hard. Finding good solutions involves combining good generalpurpose search algorithms with p ..."
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Cited by 6 (1 self)
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We describe a unified, lazy, declarative framework for solving constraint satisfaction problems, an important subclass of combinatorial search problems. These problems are both practically significant and hard. Finding good solutions involves combining good generalpurpose search algorithms with problemspecific heuristics. Conventional imperative algorithms are usually implemented and presented monolithically, which makes them hard to understand and reuse, even though new algorithms often are combinations of simpler ones. Lazy functional languages, such as Haskell, encourage modular structuring of search algorithms by separating the generation and testing of potential solutions into distinct functions communicating through an explicit, lazy intermediate data structure. But only relatively simple search algorithms have been treated in this way in the past. Our framework uses a generic generation and pruning algorithm parameterized by a labeling function that annotates search t...