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ML modules and Haskell type classes have proven to be highly effective tools for program structuring. Modules emphasize explicit configuration of program components and the use of data abstraction. Type classes emphasize implicit program construction and ad hoc polymorphism. In this paper, we show how the implicitlytyped style of type class programming may be supported within the framework of an explicitly-typed module language by viewing type classes as a particular mode of use of modules. This view offers a harmonious integration of modules and type classes, where type class features, such as class hierarchies and associated types, arise naturally as uses of existing module-language constructs, such as module hierarchies and type components. In addition, programmers have explicit control over which type class instances are available for use by type inference in a given scope. We formalize our approach as a Harper-Stone-style elaboration relation, and provide a sound type inference algorithm as a guide to implementation.

First and foremost I thank my parents for all their love and for teaching me to enjoy learning. I especially thank my wife Katie for her support and understanding through this long and sometimes stressful process. I also thank Katie for insisting on good error messages for G! My advisor, Andrew Lumsdaine, deserves many thanks for his support and guidance and for keeping the faith as I undertook this long journey away from scientific computing and into the field of programming languages. I thank my thesis committee: R. Kent Dybvig, Daniel P. Friedman, Steven D. Johnson, and Amr Sabry for their advice and encouragement. A special thanks goes to Ronald Garcia, Christopher Mueller, and Douglas Gregor for carefully editing and catching the many many times when I accidentally skipped over the important stuff. Thanks to Jaakko and Jeremiah for hours of stimulating discussions and arguments concerning separate compilation and concept-based overloading. Thanks to David Abrahams for countless hours spent debating the merits of one design over another while jogging through the hinterlands of Norway. Thanks to Alexander Stepanov and David Musser for getting all this started, and thank you for the encouragement over the years. Thanks to Matthew Austern, his book Generic Programming in the STL was both an inspiration

Scala fuses object-oriented and functional programming in a statically typed programming language. It is aimed at the construction of components and component systems. This paper gives an overview of the Scala language for readers who are familar with programming methods and programming language design.

Generic programming has recently emerged as a paradigm for developing highly reusable software libraries, most notably in C++. We have designed and implemented a constrained generics extension for C++ to support modular type checking of generic algorithms and to address other issues associated with unconstrained generics. To be as broadly applicable as possible, generic algorithms are defined with minimal requirements on their inputs. At the same time, to achieve a high degree of efficiency, generic algorithms may have multiple implementations that exploit features of specific classes of inputs. This process of algorithm specialization relies on non-local type information and conflicts directly with the local nature of modular type checking. In this paper, we review the design and implementation of our extensions for generic programming in C++, describe the issues of algorithm specialization and modular type checking in detail, and discuss the important design tradeoffs in trying to accomplish both. We present the particular design that we chose for our implementation, with the goal of hitting the sweet spot in this interesting design space.

Abstract JavaGI is an experimental language that extends Java 1.5 by generalizing the interface concept to incorporate the essential features of Haskell’s type classes. In particular, generalized interfaces cater for retroactive and constrained interface implementations, binary methods, static methods in interfaces, default implementations for interface methods, interfaces over families of types, and existential quantification for interface-bounded types. As a result, many anticipatory uses of design patterns such as Adapter, Factory, and Visitor become obsolete; several extension and integration problems can be solved more easily. JavaGI’s interface capabilities interact with subtyping (and subclassing) in interesting ways that go beyond type classes. JavaGI can be translated to Java 1.5. Its formal type system is derived from Featherweight GJ. 1

Abstract. The past decade of experience has demonstrated that the generic programming methodology is highly effective for the design, implementation, and use of large-scale software libraries. The fundamental principle of generic programming is the realization of interfaces for entire sets of components, based on their essential syntactic and semantic requirements, rather than for any particular components. Many programming languages have features for describing interfaces between software components, but none completely support the approach used in generic programming. We have recently developed G, a language designed to provide first-class language support for generic programming and large-scale libraries. In this paper, we present an overview of G and analyze the interdependence between language features and libraries design in light of a complete implementation of the Standard Template Library using G. In addition, we discuss important issues related to modularity and encapsulation in large-scale libraries and how language support for validation of components in isolation can prevent many common problems in component integration. 1

Since the Standard Template Library (STL), generic libraries in C++ rely on concepts to precisely specify the requirements of generic algorithms (function templates) on their parameters (template arguments). Modifying the definition of a concept even slightly, can have a potentially large impact on the (interfaces of the) entire library. In particular the non-local effects of a change, however, make its impact difficult to determine by hand. In this paper we propose a conceptual change impact analysis (CCIA), which determines the impact of changes of the conceptual specification of a generic library. The analysis is organized in a pipe-and-filter manner, where the first stage finds any kind of impact, the second stage various specific kinds of impact. Both stages describe reachability algorithms, which operate on a conceptual dependence graph. In a case study, we apply CCIA to a new proposal for STL iterator concepts, which is under review by the C++ standardization committee. The analysis shows a number of unexpected incompatibilities and, for certain STL algorithms, a loss of genericity. 1.

In this paper, we exploit the g 4 re infrastructure to facilitate comprehension of generic programs written in the C++ language, including class templates, instantiated class templates and specialized class templates [16]. We evaluate our 3D visualization technique using ten deployed open source applications and provide analysis about the frequency and efficiency of generic programming in these applications. 1.

Type classes were originally developed in Haskell as a disciplined alternative to ad-hoc polymorphism. Type classes have been shown to provide a type-safe solution to important challenges in software engineering and programming languages such as, for example, retroactive extension of programs. They are also recognized as a good mechanism for concept-based generic programming and, more recently, have evolved into a mechanism for type-level computation. This paper presents a lightweight approach to type classes in object-oriented (OO) languages with generics using the CONCEPT pattern and implicits (a type-directed implicit parameter passing mechanism). This paper also shows how Scala’s type system conspires with implicits to enable, and even surpass, many common extensions of the Haskell type class system, making Scala ideally suited for generic programming in the large.