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247
A Lightweight Implementation of Generics and Dynamics
, 2002
"... The recent years have seen a number of proposals for extending statically typed languages by dynamics or generics. Most proposals  if not all  require significant extensions to the underlying language. In this paper we show that this need not be the case. We propose a particularly lightweight ..."
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Cited by 74 (6 self)
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The recent years have seen a number of proposals for extending statically typed languages by dynamics or generics. Most proposals  if not all  require significant extensions to the underlying language. In this paper we show that this need not be the case. We propose a particularly lightweight extension that supports both dynamics and generics. Furthermore, the two features are smoothly integrated: dynamic values, for instance, can be passed to generic functions. Our proposal makes do with a standard HindleyMilner type system augmented by existential types. Building upon these ideas we have implemented a small library that is readily usable both with Hugs and with the Glasgow Haskell compiler.
Generic Haskell: practice and theory
 In Generic Programming, Advanced Lectures, volume 2793 of LNCS
, 2003
"... Abstract. Generic Haskell is an extension of Haskell that supports the construction of generic programs. These lecture notes describe the basic constructs of Generic Haskell and highlight the underlying theory. Generic programming aims at making programming more effective by making it more general. ..."
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Cited by 65 (23 self)
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Abstract. Generic Haskell is an extension of Haskell that supports the construction of generic programs. These lecture notes describe the basic constructs of Generic Haskell and highlight the underlying theory. Generic programming aims at making programming more effective by making it more general. Generic programs often embody nontraditional kinds of polymorphism. Generic Haskell is an extension of Haskell [38] that supports the construction of generic programs. Generic Haskell adds to Haskell the notion of structural polymorphism, the ability to define a function (or a type) by induction on the structure of types. Such a function is generic in the sense that it works not only for a specific type but for a whole class of types. Typical examples include equality, parsing and pretty printing, serialising, ordering, hashing, and so on. The lecture notes on Generic Haskell are organized into two parts. This first part motivates the need for genericity, describes the basic constructs of Generic Haskell, puts Generic Haskell into perspective, and highlights the underlying theory. The second part entitled “Generic Haskell: applications ” delves deeper into the language discussing three nontrivial applications of Generic Haskell: generic dictionaries, compressing XML documents, and a generic version of the zipper data type. The first part is organized as follows. Section 1 provides some background discussing type systems in general and the type system of Haskell in particular. Furthermore, it motivates the basic constructs of Generic Haskell. Section 2 takes a closer look at generic definitions and shows how to define some popular generic functions. Section 3 highlights the theory underlying Generic Haskell and discusses its implementation. Section 4 concludes. 1
From ML to Ada: Stronglytyped Language Interoperability via Source Translation
, 1993
"... We describe a system that supports sourcelevel integration of MLlike functional language code with ANSI C or Ada83 code. The system works by translating the functional code into typecorrect, "vanilla" C or Ada; it offers simple, efficient, typesafe interoperation between new functional code com ..."
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Cited by 65 (3 self)
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We describe a system that supports sourcelevel integration of MLlike functional language code with ANSI C or Ada83 code. The system works by translating the functional code into typecorrect, "vanilla" C or Ada; it offers simple, efficient, typesafe interoperation between new functional code components and "legacy" thirdgenerationlanguage components. Our translator represents a novel synthesis of techniques including userparameterized specification of primitive types and operators; removal of polymorphism by code specialization; removal of higherorder functions using closure datatypes and interpretation; and aggressive optimization of the resulting firstorder code, which can be viewed as encoding the result of a closure analysis. Programs remain fully typed at every stage of the translation process, using only simple, standard type systems. Target code runs at speeds comparable to the output of current optimizing ML compilers, even though handicapped by a conservative garbage collector.
For a Better Support of Static Data Flow
 Functional Programming Languages and Computer Architecture
"... . This paper identifies and solves a class of problems that arise in binding time analysis and more generally in partial evaluation of programs: the approximation and loss of static information due to dynamic expressions with static subexpressions. Solving this class of problems yields substantial b ..."
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Cited by 59 (16 self)
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. This paper identifies and solves a class of problems that arise in binding time analysis and more generally in partial evaluation of programs: the approximation and loss of static information due to dynamic expressions with static subexpressions. Solving this class of problems yields substantial binding time improvements and thus dramatically better results not only in the case of partial evaluation but also for static analyses of programs  this last point actually is related to a theoretical result obtained by Nielson. Our work can also be interpreted as providing a solution to the problem of conditionally static data, the dual of partially static data. We point out which changes in the control flow of a source program may improve its static data flow. Unfortunately they require one to iterate earlier phases of partial evaluation. We show how these changes are subsumed by transforming the source program into continuationpassing style (CPS). The transformed programs get specializ...
Dynamics in ML
, 1993
"... Objects with dynamic types allow the integration of operations that essentially require runtime typechecking into staticallytyped languages. This article presents two extensions of the ML language with dynamics, based on our work on the CAML implementation of ML, and discusses their usefulness. ..."
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Cited by 56 (0 self)
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Objects with dynamic types allow the integration of operations that essentially require runtime typechecking into staticallytyped languages. This article presents two extensions of the ML language with dynamics, based on our work on the CAML implementation of ML, and discusses their usefulness. The main novelty of this work is the combination of dynamics with polymorphism.
Revisiting Catamorphisms over Datatypes with Embedded Functions (or, Programs from Outer Space)
 In Conf. Record 23rd ACM SIGPLAN/SIGACT Symp. on Principles of Programming Languages, POPL’96, St. Petersburg Beach
, 1996
"... We revisit the work of Paterson and of Meijer & Hutton, which describes how to construct catamorphisms for recursive datatype definitions that embed contravariant occurrences of the type being defined. Their construction requires, for each catamorphism, the definition of an anamorphism that has an i ..."
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Cited by 54 (3 self)
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We revisit the work of Paterson and of Meijer & Hutton, which describes how to construct catamorphisms for recursive datatype definitions that embed contravariant occurrences of the type being defined. Their construction requires, for each catamorphism, the definition of an anamorphism that has an inverselike relationship to that catamorphism. We present an alternative construction, which replaces the stringent requirement that an inverse anamorphism be defined for each catamorphism with a more lenient restriction. The resulting construction has a more efficient implementation than that of Paterson, Meijer, and Hutton and the relevant restriction can be enforced by a HindleyMilner type inference algorithm. We provide numerous examples illustrating our method. 1 Introduction Functional programmers often use catamorphisms (or fold functions) as an elegant means of expressing algorithms over algebraic datatypes. Catamorphisms have also been used by functional programmers as a medium in ...
Runtime Principals in Informationflow Type Systems
 In IEEE Symposium on Security and Privacy
, 2004
"... for enforcing strong endtoend confidentiality and integrity policies. Such policies, however, are usually specified in term of static informationdata is labeled high or low security at compile time. In practice, the confidentiality of data may depend on information available only while the sys ..."
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Cited by 54 (10 self)
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for enforcing strong endtoend confidentiality and integrity policies. Such policies, however, are usually specified in term of static informationdata is labeled high or low security at compile time. In practice, the confidentiality of data may depend on information available only while the system is running This paper studies language support for runtime principals, a mechanism for specifying informationflow security policies that depend on which principals interact with the system. We establish the basic property of noninterference for programs written in such language, and use runtime principals for specifying runtime authority in downgrading mechanisms such as declassification.
Typed Combinators for Generic Traversal
 Proc. of PADL 2002
, 2002
"... Lacking support for generic traversal, functional programming languages suffer from a scalability problem when applied to largescale program transformation problems. As a solution, we introduce functional strategies: typeful generic functions that not only can be applied to terms of any type, bu ..."
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Cited by 53 (22 self)
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Lacking support for generic traversal, functional programming languages suffer from a scalability problem when applied to largescale program transformation problems. As a solution, we introduce functional strategies: typeful generic functions that not only can be applied to terms of any type, but which also allow generic traversal into subterms.
Merging Monads and Folds for Functional Programming
 In Advanced Functional Programming, LNCS 925
, 1995
"... . These notes discuss the simultaneous use of generalised fold operators and monads to structure functional programs. Generalised fold operators structure programs after the decomposition of the value they consume. Monads structure programs after the computation of the value they produce. Our progra ..."
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Cited by 49 (2 self)
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. These notes discuss the simultaneous use of generalised fold operators and monads to structure functional programs. Generalised fold operators structure programs after the decomposition of the value they consume. Monads structure programs after the computation of the value they produce. Our programs abstract both from the recursive processing of their input as well as from the sideeffects in computing their output. We show how generalised monadic folds aid in calculating an efficient graph reduction engine from an inefficient specification. 1 Introduction Should I structure my program after the decomposition of the value it consumes or after the computation of the value it produces? Some [Bir89, Mee86, Mal90, Jeu90, MFP91] argue in favour of structuring programs after the decomposition of the value they consume. Such syntax directed programs are written using a limited set of recursion functionals. These functionals, called catamorphisms or generalised fold operators are naturally ...
Recursive Monadic Bindings
, 2000
"... Monads have become a popular tool for dealing with computational effects in Haskell for two significant reasons: equational reasoning is retained even in the presence of effects; and program modularity is enhanced by hiding "plumbing" issues inside the monadic infrastructure. Unfortunately, not all ..."
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Cited by 43 (4 self)
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Monads have become a popular tool for dealing with computational effects in Haskell for two significant reasons: equational reasoning is retained even in the presence of effects; and program modularity is enhanced by hiding "plumbing" issues inside the monadic infrastructure. Unfortunately, not all the facilities provided by the underlying language are readily available for monadic computations. In particular, while recursive monadic computations can be defined directly using Haskell's builtin recursion capabilities, there is no natural way to express recursion over the values of monadic actions. Using examples, we illustrate why this is a problem, and we propose an extension to Haskell's donotation to remedy the situation. It turns out that the structure of monadic valuerecursion depends on the structure of the underlying monad. We propose an axiomatization of the recursion operation and provide a catalogue of definitions that satisfy our criteria.