Since the introduction of object-oriented programming few programminglanguages have attempted to provide programmers with more than objects and classes, i.e., more than two levels. Those that did, almost exclusively ...
详细信息
ISBN:
(纸本)9781595937865
Since the introduction of object-oriented programming few programminglanguages have attempted to provide programmers with more than objects and classes, i.e., more than two levels. Those that did, almost exclusively aimed at describing language properties - i. e., their metaclasses exert linguistic control on language concepts and mechanisms often in order to make the language extensible. In terms of supporting logical domain classification levels, however, they are still limited to two levels. In this paper we conservatively extend the object-oriented programming paradigm to feature an unbounded number of domain classification levels. We can therefore avoid the introduction of accidental complexity into programs caused by accommodating multiple domain levels within only two programming levels. We present a corresponding languagedesign featuring "deep instantiation" and demonstrate its features with a running example. Finally, we outline the implementation of our compiler prototype and discuss the potentials of further developing our languagedesign.
The MLF type system by Le Botlan and Remy (2003) is a natural extension of Hindley-Milner type inference that supports full first-class polymorphism, where types can be of higher-rank and impredicatively instantiated....
详细信息
ISBN:
(纸本)9781595938152
The MLF type system by Le Botlan and Remy (2003) is a natural extension of Hindley-Milner type inference that supports full first-class polymorphism, where types can be of higher-rank and impredicatively instantiated. Even though MLF is theoretically very attractive, it has not seen widespread adoption. We believe that this partly because it is unclear how the rich language of MLF types relate to standard System F types. In this article we give the first type directed translation of MLF terms to System F terms. Based on insight gained from this translation, we also define "Rigid MLF" (MLF=), a restriction of MLF where all bound values have a System F type. The expressiveness of MLF= is the same as that of boxy types, but MLF= needs fewer annotations and we give a detailed comparison between them.
Perl is a general-purpose language, known for its vast number of freely available libraries. The Perl 6 project was started to improve the language's support for multi-paradigmatic programming, while retaining com...
详细信息
ISBN:
(纸本)9781595935755
Perl is a general-purpose language, known for its vast number of freely available libraries. The Perl 6 project was started to improve the language's support for multi-paradigmatic programming, while retaining compatibility with the existing code base. This talk discusses how Perl 6 attempts to reconcile various competing paradigms in the field of programminglanguagedesign, such as static vs. dynamic typechecking, nominal vs. structural subtyping, prototype vs. class-based objects, and lazy vs. eager evaluation. Moreover, this talk also covers the design and development of Pugs, a self-hosting Perl 6 implementation bootstrapped from Haskell, targeting multiple runtime environments, including Perl 5, JavaScript and Parrot.
Operators for delimiting control and for capturing composable continuations litter the landscape of theoretical programminglanguage research. Numerous papers explain their advantages, how the operators explain each o...
详细信息
ISBN:
(纸本)9781595938152
Operators for delimiting control and for capturing composable continuations litter the landscape of theoretical programminglanguage research. Numerous papers explain their advantages, how the operators explain each other (or don't), and other aspects of the operators' existence. Production programminglanguages, however, do not support these operators, partly because their relationship to existing and demonstrably useful constructs-such as exceptions and dynamic binding-remains relatively unexplored. In this paper, we report on our effort of translating the theory of delimited and composable control into a viable implementation for a production system. The report shows how this effort involved a substantial design element, including work with a formal model, as well as significant practical exploration and engineering. The resulting version of PLT Scheme incorporates the expressive combination of delimited and composable control alongside dynamic-wind, dynamic binding, and exception handling. None of the additional operators subvert the intended benefits of existing control operators, so that programmers can freely mix and match control operators.
A transient hardware fault occurs when an energetic particle strikes a transistor, causing it to change state. Although transient faults do not permanently damage the hardware, they may corrupt computations by alterin...
详细信息
ISBN:
(纸本)9781595936332
A transient hardware fault occurs when an energetic particle strikes a transistor, causing it to change state. Although transient faults do not permanently damage the hardware, they may corrupt computations by altering stored values and signal transfers. In this paper, we propose a new scheme for provably safe and reliable computing in the presence of transient hardware faults. In our scheme, software computations are replicated to provide redundancy while special instructions compare the independently computed results to detect errors before writing critical data. In stark contrast to any previous efforts in this area, we have analyzed our fault tolerance scheme from a formal, theoretical perspective. To be specific, first, we provide an operational semantics for our assembly language, which includes a precise formal definition of our fault model. Second, we develop an assembly-level type system designed to detect reliability problems in compiled code. Third, we provide a formal specification for program fault tolerance under the given fault model and prove that all well-typed programs are indeed fault tolerant. In addition to the formal analysis, we evaluate our detection scheme and show that it only takes 34% longer to execute than the unreliable version.
In this paper we introduce the iTask system: a set of combinators to specify work flows in a pure functional language at a very high level of abstraction. Work flow systems are automated systems in which tasks are coo...
详细信息
In this paper we introduce the iTask system: a set of combinators to specify work flows in a pure functional language at a very high level of abstraction. Work flow systems are automated systems in which tasks are coordinated that have to be executed by humans and computers. The combinators that we propose support work flow patterns commonly found in commercial work flow systems. Compared with most of these commercial systems, the iTask system offers several advantages: tasks are statically typed, tasks can be higher order, the combinators are fully compositional, dynamic and recursive work flows can be specified, and last but not least, the specification is used to generate an executable web-based multi-user work flow application. With the iTask system, useful work flows can be defined which cannot be expressed in other systems: work can be interrupted and subsequently directed to other workers for further processing. The implementation is special as well. It is based on the Clean iData toolkit which makes it possible to create fully dynamic, interactive, thin client web applications. Thanks to the generic programming techniques used in the iData toolkit, the programming effort is reduced significantly: state handling, form rendering, user interaction, and storage management is handled automatically. The iTask system allows a task to be regarded as a special kind of persistent redex being reduced by the application user via task completion. The combinators control the order in which these redexes are made available to the application user. The system rewrites the persistent task redexes in a similar way as functions are rewritten in lazy functional languages.
Transactional memory provides a new concurrency control mechanism that avoids many of the pitfalls of lock-based synchronization. High-performance software transactional memory (STM) implementations thus far provide w...
详细信息
ISBN:
(纸本)9781595936332
Transactional memory provides a new concurrency control mechanism that avoids many of the pitfalls of lock-based synchronization. High-performance software transactional memory (STM) implementations thus far provide weak atomicity: Accessing shared data both inside and outside a transaction can result in unexpected, implementation-dependent behavior. To guarantee isolation and consistent ordering in such a system, programmers are expected to enclose all shared-memory accesses inside transactions. A system that provides strong atomicity guarantees isolation even in the presence of threads that access shared data outside transactions. A strongly-atomic system also orders transactions with conflicting non-transactional memory operations in a consistent manner. In this paper, we discuss some surprising pitfalls of weak atomicity, and we present an STM system that avoids these problems via strong atomicity. We demonstrate how to implement non-transactional data accesses via efficient read and write barriers, and we present compiler optimizations that further reduce the overheads of these barriers. We introduce a dynamic escape analysis that differentiates private and public data at runtime to make barriers cheaper and a static not-accessed-in-transaction analysis that removes many barriers completely. Our results on a set of Java programs show that strong atomicity can be implemented efficiently in a high-performance STM system.
This paper tells the story of the development of BETA: a programminglanguage with just one abstraction mechanism, instead of one abstraction mechanism for each kind of program element (classes, types, procedures, fun...
详细信息
Performance of stencil computations can be significantly improved through smart implementations that improve memory locality, computation reuse, or parallelize the computation. Unfortunately, efficient implementations...
详细信息
Performance of stencil computations can be significantly improved through smart implementations that improve memory locality, computation reuse, or parallelize the computation. Unfortunately, efficient implementations are hard to obtain because they often involve non-traditional transformations, which means that they cannot be produced by optimizing the reference stencil with a compiler. In fact, many stencils are produced by code generators that were tediously handcrafted. In this paper, we show how stencil implementations can be produced with sketching. Sketching is a software synthesis approach where the programmer develops a partial implementation a sketch-and a separate specification of the desired functionality given by a reference (unoptimized) stencil. The synthesizer then completes the sketch to behave like the specification, filling in code fragments that are difficult to develop manually. Existing sketching systems work only for small finite programs, i.e., programs that can be represented as small Boolean circuits. In this paper, we develop a sketching synthesizer that works for stencil computations, a large class of programs that, unlike circuits, have unbounded inputs and outputs, as well as an unbounded number of computations. The key contribution is a reduction algorithm that turns a stencil into a circuit, allowing us to synthesize stencils using an existing sketching synthesizer.
The JastAdd Extensible Java Compiler is a high quality Java compiler that is easy to extend in order to build static analysis tools for Java, and to extend Java with new language constructs. It is built modularly, wit...
详细信息
ISBN:
(纸本)9781595937865
The JastAdd Extensible Java Compiler is a high quality Java compiler that is easy to extend in order to build static analysis tools for Java, and to extend Java with new language constructs. It is built modularly, with a Java 1.4 compiler that is extended to a Java 5 compiler. Example applications that are built as extensions include an alternative backend that generates Jimple, an extension of Java with AspectJ constructs, and the implementation of a pluggable type system for non-null checking and inference. The system is implemented using JastAdd, a declarative Java-like language. We describe the compiler architecture, the major design ideas for building and extending the compiler, in particular, for dealing with complex extensions that affect name and type analysis. Our extensible compiler compares very favorably concerning quality, speed and size with other extensible Java compiler frameworks. It also compares favorably in quality and size compared with traditional non-extensible Java compilers, and it runs within a factor of three compared to javac.
暂无评论