231 research outputs found
Group Communication Patterns for High Performance Computing in Scala
We developed a Functional object-oriented Parallel framework (FooPar) for
high-level high-performance computing in Scala. Central to this framework are
Distributed Memory Parallel Data structures (DPDs), i.e., collections of data
distributed in a shared nothing system together with parallel operations on
these data. In this paper, we first present FooPar's architecture and the idea
of DPDs and group communications. Then, we show how DPDs can be implemented
elegantly and efficiently in Scala based on the Traversable/Builder pattern,
unifying Functional and Object-Oriented Programming. We prove the correctness
and safety of one communication algorithm and show how specification testing
(via ScalaCheck) can be used to bridge the gap between proof and
implementation. Furthermore, we show that the group communication operations of
FooPar outperform those of the MPJ Express open source MPI-bindings for Java,
both asymptotically and empirically. FooPar has already been shown to be
capable of achieving close-to-optimal performance for dense matrix-matrix
multiplication via JNI. In this article, we present results on a parallel
implementation of the Floyd-Warshall algorithm in FooPar, achieving more than
94 % efficiency compared to the serial version on a cluster using 100 cores for
matrices of dimension 38000 x 38000
Fighting bit Rot with Types (Experience Report: Scala Collections)
We report on our experiences in redesigning Scala\u27s collection
libraries, focussing on the role that type systems play in keeping
software architectures coherent over time. Type systems can make
software architecture more explicit but, if they are too weak, can
also cause code duplication. We show that code duplication can be
avoided using two of Scala\u27s type constructions: higher-kinded types
and implicit parameters and conversions
Modular implicits
We present modular implicits, an extension to the OCaml language for ad-hoc
polymorphism inspired by Scala implicits and modular type classes. Modular
implicits are based on type-directed implicit module parameters, and elaborate
straightforwardly into OCaml's first-class functors. Basing the design on
OCaml's modules leads to a system that naturally supports many features from
other languages with systematic ad-hoc overloading, including inheritance,
instance constraints, constructor classes and associated types
Exploring the flexibility of scala implicits towards an extensible live environment
Tese de mestrado integrado. Engenharia InformĆ”tica e ComputaĆ§Ć£o. Faculdade de Engenharia. Universidade do Porto. 201
BSP-fields: An Exact Representation of Polygonal Objects by Differentiable Scalar Fields Based on Binary Space Partitioning
The problem considered in this work is to find a dimension independent algorithm for the generation of signed scalar fields exactly representing polygonal objects and satisfying the following requirements: the defining real function takes zero value exactly at the polygonal object boundary; no extra zero-value isosurfaces should be generated; C1 continuity of the function in the entire domain. The proposed algorithms are based on the binary space partitioning (BSP) of the object by the planes passing through the polygonal faces and are independent of the object genus, the number of disjoint components, and holes in the initial polygonal mesh. Several extensions to the basic algorithm are proposed to satisfy the selected optimization criteria. The generated BSP-fields allow for applying techniques of the function-based modeling to already existing legacy objects from CAD and computer animation areas, which is illustrated by several examples
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On implicit program constructs
Session types are a well-established approach to ensuring protocol conformance and the absence of communication errors such as deadlocks in message passing systems.
Implicit parameters, introduced by Haskell and popularised in Scala, are a mechanism to improve program readability and conciseness by allowing the programmer to omit function call arguments, and have the compiler insert them in a principled manner at compile-time. Scala recently gave implicit types first-class status (implicit functions), yielding an expressive tool for handling context dependency in a type-safe manner.
DOT (Dependent Object Types) is an object calculus with path-dependent types and abstract type members, developed to serve as a theoretical foundation for the Scala programming language. As yet, DOT does not model all of Scalaās features, but a small subset. Among those features of Scala not yet modelled by DOT are implicit functions.
We ask: can type-safe implicit functions be generalised from Scalaās sequential setting to message passing computation, to improve readability and conciseness of message passing programs? We answer this question in the affirmative by generalising the concept of an implicit function to an implicit message, its concurrent analogue, a programming language construct for session-typed concurrent computation.
We explore new applications for implicit program constructs by integrating theminto four novel calculi, each demonstrating a new use case or theoretical result for implicits.
Firstly, we integrate implicit functions and messages into the concurrent functional language LAST, Gay and Vasconcelosās calculus of linear types for asynchronous sessions. We demonstrate their utility by example, and explore use cases for both implicit functions and implicit messages.
We integrate implicit messages into two pi calculi, further demonstrating the robustness of our approach to extending calculi with implicits. We show that implicit messages are possible in the absence of lambda calculus, in languages with concurrency primitives only, and that they are sound not only in binary session-typed computation, but also in multi-party context.
Finally we extend DOT to include implicit functions. We show type safety of the resulting calculus by translation to DOT, lending a higher degree of confidence to the correctness of implicit functions in Scala. We demonstrate that typical use cases for implicit functions in Scala are typably expressible in DOT when extended with implicit functions
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