Scheme 2003: proceedings of the fourth workshop on scheme and functional programming

technical reportThis report contains the papers presented at the Fourth Workshop on Scheme and Functional Programming. The purpose of the Scheme Workshop is to discuss experience with and future developments of the Scheme programming language?including the future of Scheme standardization?as well as general aspects of computer science loosely centered on the general theme of Scheme

Language Support for Distributed Functional Programming

Software development has taken a fundamental turn. Software today has gone from simple, closed programs running on a single machine, to massively open programs, patching together user experiences byway of responses received via hundreds of network requests spanning multiple machines. At the same time, as data continues to stockpile, systems for big data analytics are on the rise. Yet despite this trend towards distributing computation, issues at the level of the language and runtime abound. Serialization is still a costly runtime affair, crashing running systems and confounding developers. Function closures are being added to APIs for big data processing for use by end-users without reliably being able to transmit them over the network. And much of the frameworks developed for handling multiple concurrent requests byway of asynchronous programming facilities rely on blocking threads, causing serious scalability issues. This thesis describes a number of extensions and libraries for the Scala programming language that aim to address these issues and to provide a more reliable foundation on which to build distributed systems. This thesis presents a new approach to serialization called pickling based on the idea of generating and composing functional pickler combinators statically. The approach shifts the burden of serialization to compile time as much as possible, enabling users to catch serialization errors at compile time rather than at runtime. Further, by virtue of serialization code being generated at compile time, our framework is shown to be significantly more performant than other state-of-the-art serialization frameworks. We also generalize our technique for generating serialization code to generic functions other than pickling. Second, in light of the trend of distributed data-parallel frameworks being designed around functional patterns where closures are transmitted across cluster nodes to large-scale persistent datasets, this thesis introduces a new closure-like abstraction and type system, called spores, that can guarantee closures to be serializable, thread-safe, or even have custom user-defined properties. Crucially, our system is based on the principle of encoding type information corresponding to captured variables in the type of a spore. We prove our type system sound, implement our approach for Scala, evaluate its practicality through a small empirical study, and show the power of these guarantees through a case analysis of real-world distributed and concurrent frameworks that this safe foundation for closures facilitates. Finally, we bring together the above building blocks, pickling and spores, to form the basis of a new programming model called function-passing. Function-passing is based on the idea of a distributed persistent data structure which stores in its nodes transformations to data rather than the distributed data itself, simplifying fault recovery by design. Lazy evaluation is also central to our model; by incorporating laziness into our design only at the point of initiating network communication, our model remains easy to reason about while remaining efficient in time and memory. We formalize our programming model in the form of a small-step operational semantics which includes a precise specification of the semantics of functional fault recovery, and we provide an open-source implementation of our model in and for Scala

Towards an aspect weaving BPEL engine

This position paper proposes the use of dynamic aspects and the visitor design pattern to obtain a highly configurable and extensible BPEL engine. Using these two techniques, the core of this infrastructural software can be customised to meet new requirements and add features such as debugging, execution monitoring, or changing to another Web Service selection policy. Additionally, it can easily be extended to cope with customer-specific BPEL extensions. We propose the use of dynamic aspects not only on the engine itself but also on the workflow in order to tackle the problems of Web Service hot deployment and hot fixes to long running processes. In this way, composing aWeb Service "on-the-fly" means weaving its choreography interface into the workflow

A survey of practical software adaptation techniques

Abstract: Software adaptation techniques appear in many disparate areas of research literature, and under many guises. This paper enables a clear and uniform understanding of the related research, in three ways. Firstly, it surveys a broad range of relevant research, describing and contrasting the approaches of each using a uniform terminological and conceptual vocabulary. Secondly, it identifies and discusses three commonly advocated principles within this work: component models, first-class connection and loose coupling. Thirdly, it identifies and compares the various modularisation strategies employed by the surveyed work

Programmiersprachen und Rechenkonzepte

Seit 1984 veranstaltet die GI-Fachgruppe "Programmiersprachen und Rechenkonzepte" regelmäßig im Frühjahr einen Workshop im Physikzentrum Bad Honnef. Das Treffen dient in erster Linie dem gegenseitigen Kennenlernen, dem Erfahrungsaustausch, der Diskussion und der Vertiefung gegenseitiger Kontakte. In diesem Forum werden Vorträge und Demonstrationen sowohl bereits abgeschlossener als auch noch laufender Arbeiten vorgestellt, unter anderem (aber nicht ausschließlich) zu Themen wie - Sprachen, Sprachparadigmen - Korrektheit von Entwurf und Implementierung - Werkzeuge - Software-/Hardware-Architekturen - Spezifikation, Entwurf - Validierung, Verifikation - Implementierung, Integration - Sicherheit (Safety und Security) - eingebettete Systeme - hardware-nahe Programmierung. In diesem Technischen Bericht sind einige der präsentierten Arbeiten zusammen gestellt

Pharmacological therapies for monogenic obesity caused by MC4R dysfunction

PhDMutations in the melanocortin-4 receptor (MC4R) are the most common cause of monogenic obesity. The majority of MC4R mutations are predicted to cause the receptor to aberrantly fold. Misfolded MC4R fails to traffic to the plasma membrane (PM) and is retained in the endoplasmic reticulum (ER). Recent studies with other G-protein coupled receptors have shown that stabilisation of misfolded receptor, by pharmacological chaperones, promotes trafficking to the cell surface where the receptor may be functional. The objective of this thesis was to develop a rapid throughput cell culture based assay to monitor MC4R trafficking to the PM and to screen chemical chaperones and inducers and inhibitors of endogenous molecular chaperones, for the ability to promote folding and cell surface expression of mutant MC4R. The work presented here confirmed that clinically occurring MC4R mutants S58C, N62S, P78L, D90N, L106P, C271Y and P299H are intracellularly retained in HEK 293 cells. The cell culture assay was used to screen a number of compounds, which have been previously reported to act as chemical chaperones by stabilising protein folding. Treatment with 4-phenyl butyric acid (4-PBA) and trehalose increased total cellular levels of wild-type and mutant MC4R. The benzoquinone ansamycin, geldanamycin, has been identified as a potent inhibitor of Hsp90 activity and an inducer of the heat shock response. Geldanamycin treatment altered the cell surface expression of wild-type and mutant MC4R. Furthermore, over expression of Hsp90 co-chaperone Aha1, also effected MC4R processing. Over-expression of Hsp70 has been shown to promote the trafficking of other aberrantly folded proteins. Over-expression of Hsc70 increased trafficking levels of wild-type and mutant MC4R and promoted mutant MC4R functional expression. In conclusion this data suggests using compounds that stabilise protein folding and/or targeting endogenous molecular chaperone machineries may have efficacy for altering cell surface expression of mutant MC4R

Slicing techniques applied to architectural analysis of legacy software

Tese de doutoramento em Informática (ramo de conhecimento em Fundamentos da Computação)Program understanding is emerging as a key concern in software engineering. In a situation in which the only quality certificate of the running software artifact still is life-cycle endurance, customers and software producers are little prepared to modify or improve running code. However, faced with so risky a dependence on legacy software, managers are more and more prepared to spend resources to increase confidence on - i.e., the level of understanding of - their (otherwise untouchable) code. In fact the technological and economical relevance of legacy software as well as the complexity of their re-engineering entails the need for rigour. Addressing such a scenario, this thesis advocates the use of direct source code analysis for both the process of understanding and transformation of software systems. In particular, the thesis focuses on the development and application of slicing techniques at both the “micro" and “macro" structural levels of software. The former, deals with fine-grained structures of programs, slicing operating over elementary program entities, such as types, variables or procedure identifiers. The latter, on the other hand, addresses architectural issues and interaction modes across modules, components or services upon which a system is decomposed. At the \micro" level this thesis delves into the problem of slicing functional programs, a paradigm that is gaining importance and was generally neglected by the slicing community. Three different approaches to functional slicing are proposed, accompanied by the presentation of the HaSlicer application, a software tool developed as a proof-of-concept for some of the ideas discussed. A comparison between the three approaches, their practical application and the motivational aspects for keeping investigating new functional slicing processes are also discussed. Slicing at a \macro" level is the theme of the second part of this thesis, which addresses the problem of extracting from source code the system's coordination model which governs interaction between its components. This line of research delivers two approaches for abstracting software systems coordination models, one of the most vital structures for software architectural analysis. Again, a software tool – CoordInspector – is introduced as a proof-of-concept.A compreensão de sistemas de software reveste-se de uma cada vez maior importância no campo da engenharia de software. Numa situação em que a única garantia de funcionamento dos diversos componentes de software reside apenas na metodologia de desenvolvimento adoptada, tanto clientes bem como produtores de software encontram-se pouco preparados para modificar ou melhorar os seus programas. No entanto, face a uma tão grande dependência em relação ao código legado, os gestores estão cada vez mais receptivos a gastar recursos de forma a aumentar a confiança - i.e., o nível de compreensão - dos seus (de outra forma intocáveis) programas. De facto, a relevância tecnológica e económica do software legado bem como a complexidade associada à sua reengenharia provocam uma urgente necessidade de rigor. Tendo este cenário como contexto, esta tese advoga o uso de uma análise directa de código fonte com o objectivo de compreender e transformar sistemas de software. Em particular, esta tese debruça-se sobre o desenvolvimento e a aplicação de técnicas de slicing aos níveis “micro" e “macro" das estruturas de software. A análise efectuada ao nível “micro" lida com estruturas de programas de pequena granularidade, onde o slicing opera sobre entidades elementares dos programas, tais como tipos, variáveis ou identificadores de procedimentos. Por outro lado, o nível de análise “macro" aborda questões arquitecturais, tais como as interacção entre módulos, componentes ou serviços sobre os quais um sistema de software pode ser decomposto. Ao nível “micro", esta tese aborda o problema de efectuar slicing a programas funcionais, um paradigma que se reveste de uma cada vez maior importância e o qual tem sido negligenciado pela comunidade de slicing. Neste sentido, esta tese apresenta três diferentes abordagens ao slicing funcional, acompanhadas pela apresentação da aplicação HaSlicer, uma ferramenta de software desenvolvida como prova de conceito para algumas das ideias expostas. No decorrer da apresentação destas propostas de abordagem ao slicing funcional, efectua-se ainda uma comparação entre os diversos processos, as suas aplicações práticas bem como os aspectos motivacionais que levaram à investigação de novos processos de slicing funcional. As operações de slicing ao nível “macro" constituem o tema da segunda parte desta tese, onde se aborda o problema específico da extracção de arquitecturas de sistemas de software. Neste sentido, são desenvolvidas duas abordagens distintas para a abstracção do modelo de coordenação de um sistema de software, o que constitui uma das mais vitais estruturas para a análise de sistemas de software. Mais uma vez, é apresentada uma ferramenta de software – CoordInspector – como prova de conceito.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/19127/200

gbeta - a Language with Virtual Attributes, Block Structure, and Propagating, Dynamic Inheritance

A language design development process is presented which leads to a language, gbeta, with a tight integration of virtual classes, general block structure, and a multiple inheritance mechanism based on coarse-grained structural type equivalence. From this emerges the concept of propagating specialization. The power lies in the fact that a simple expression can have far-reaching but well-organized consequences, e.g., in one step causing the combination of families of classes, then by propagation the members of those families, and finally by propagation the methods of the members. Moreover, classes are first class values which can be constructed at run-time, and it is possible to inherit from classes whether or not they are compile-time constants, and whether or not they were created dynamically. It is also possible to change the class and structure of an existing object at run-time, preserving object identity. Even though such dynamism is normally not seen in statically type-checked languages, these constructs have been integrated without compromising the static type safety of the language

Programming Languages and Systems

This open access book constitutes the proceedings of the 28th European Symposium on Programming, ESOP 2019, which took place in Prague, Czech Republic, in April 2019, held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2019