Fusing Logic And Control With Local Transformations: An Example Optimization

Programming supports the separation of logical concerns from issues of control in program construction. While this separation of concerns leads to reduced code size and increased reusability of code, its main disadvantage is the computational overhead it incurs. Fusion techniques can be used to combine the reusability of abstract programs with the efficiency of specialized programs. In this paper we illustrate some of the ways in which rewriting strategies can be used to separate the definition of program transformation rules from the strategies under which they are applied. Doing so supports the generic definition of program transformation components. Fusion techniques for strategies can then be used to specialize such generic components. We show how the generic innermost rewriting strategy can be optimized by fusing it with the rules to which it is applied. Both the optimization and the programs to which the optimization applies are specified in the strategy language Stratego. The optimization is based on small transformation rules that are applied locally under the control of strategies, using special knowledge about the contexts in which the rules are applied

Self-Organizing Software Architectures

Looking at engineering productivity is a source for improving the state of software engineering. We present two approaches to improve productivity: bottom-up modeling and self-configuring software components. Productivity, as measured in the ability to produce correctly working software features using limited resources is improved by performing less wasteful activities and by concentrating on the required activities to build sustainable software development organizations. Bottom-up modeling is a way to combine improved productivity with agile software engineering. Instead of focusing on tools and up-front planning, the models used emerge, as the requirements to the product are unveiled during a project. The idea is to build the modeling formalisms strong enough to be employed in code generation and as runtime models. This brings the benefits of model-driven engineering to agile projects, where the benefits have been rare. Self-configuring components are a development of bottom-up modeling. The notion of a source model is extended to incorporate the software entities themselves. Using computational reflection and introspection, dependent components of the software can be automatically updated to reflect changes in the dependence. This improves maintainability, thus making software changes faster. The thesis contains a number of case studies explaining the ways of applying the presented techniques. In addition to constructing the case studies, an empirical validation with test subjects is presented to show the usefulness of the techniques.Itseorganisoituvat ohjelmistoarkkitehtuurit Ohjelmistokehityksen tuottavuus on monen ohjelmistokehitysorganisaation huolenaihe. Erityisesti ylläpitovaiheessa ohjelmistojen heikko muokattavuus tuottaa turhia kustannuksia ja pettymyksiä asiakassuhteissa, kun vaikeasti muokattavaan ohjelmistoon tulisi tehdä muutoksia. Tässä työssä esitetään kaksi menetelmää ohjelmistojen muokattavuuden parantamiseksi: kokoava mallinnuskielten käyttäminen sekä itseorganisoituvat ohjelmistokomponentit. Mallipohjaisessa ohjelmistotuotannossa ohjelmistoille kehitetään soveltuvat mallinnuskielet ja -työkalut, joiden pohjalta kehitettävä ohjelmisto voidaan automaattisesti tuottaa. Uuden mallinnuskielen kehittäminen ja sitä tukevan välineistön rakentaminen on kuitenkin aikaaviepää ja vaikeaa. Vaarana on, että kehitetty kieli on valmistuessaan vanhentunut. Niin kutsutuissa ketterissä ohjelmistomenetelmissä yritetään välttää perinteisten, suunittelupainotteisten kehitysmenetelmien tuottamia sudenkuoppia. Liiallinen ketteryys voi kuitenkin kostautua heikkona tuottavuutena, kun kehitysväen kaikki aika kuluu näppäryysharjoituksiin varsinaisen tuottavan työn sijaan. Kokoava mallipohjainen tuotanto keskittyy kehittämään vain riittävän hyviä malleja, joiden perusteella voidaan yhdistää mallipohjaisen ohjelmistotuotannon ja ketterien prosessimallien tuomat edut. Ulkoisten, erikseen kehiteltyjen mallikielten lisäksi työssä esitellään ajatus ohjelmakoodin itsensä käyttämisestä mallipohjaisen ohjelmistotuotannon työkaluna. Näin syntyy itseorganisoituva ohjelmistoarkkitehtuuri. Tällä tavoin kehitystyön tuottavuus paranee, sillä ohjelmakoodin sisäisten riippuvuuksien määrä laskee, ja näin ollen muokkausten tekeminen on helpompaa. Työssä esitellään tapaustutkimuksia ohjelmakoodiin perustuvasta mallipohjaisen ohjelmistotuotannon ohjelmistokehyksistä sekä empiirinen validointi itseorganisoituvuuden hyödyllisyydestä tuottavuusnäkökulmasta katsoen

Categorical semantics and composition of tree transducers

In this thesis we see two new approaches to compose tree transducers and more general to fuse functional programs. The first abroach is based on initial algebras. We prove a new variant of the acid rain theorem for mutually recursive functions where the build function is substituted by a concrete functor. Moreover, we give a symmetric form (i.e. consumer and producer have the same syntactic form) of our new acid rain theorem where fusion is composition in a category and thus in particular associative. Applying this to compose top-down tree transducers yields the same result (on a syntactic level) as the classical top-down tree transducer composition. The second approach is based on free monads and monad transformers. In the same way as monoids are used in the theory of character string automata, we use monads in the theory of tree transducers. We generalize the notion of a tree transducer defining the monadic transducer, and we prove an according fusion theorem. Moreover, we prove that homomorphic monadic transducers are semantically equivalent. The latter makes it possible to compose syntactic classes of tree transducers (or particular functional programs) by simply composing endofunctors

Shortest Route at Dynamic Location with Node Combination-Dijkstra Algorithm

Abstract— Online transportation has become a basic requirement of the general public in support of all activities to go to work, school or vacation to the sights. Public transportation services compete to provide the best service so that consumers feel comfortable using the services offered, so that all activities are noticed, one of them is the search for the shortest route in picking the buyer or delivering to the destination. Node Combination method can minimize memory usage and this methode is more optimal when compared to A* and Ant Colony in the shortest route search like Dijkstra algorithm, but can’t store the history node that has been passed. Therefore, using node combination algorithm is very good in searching the shortest distance is not the shortest route. This paper is structured to modify the node combination algorithm to solve the problem of finding the shortest route at the dynamic location obtained from the transport fleet by displaying the nodes that have the shortest distance and will be implemented in the geographic information system in the form of map to facilitate the use of the system. Keywords— Shortest Path, Algorithm Dijkstra, Node Combination, Dynamic Location (key words

African Futures

This collection brings together scholars from different disciplines. In short and provocative essays, they shine their light on the often ambivalent and contradictory possibilities and challenges people in Africa are facing. Africa, indeed, has many futures