| 1. |
- Arvidsson, Ellen, et al.
(författare)
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Reference Capabilities for Flexible Memory Management
- 2023
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Ingår i: Proceedings of the ACM on Programming Languages. - : Association for Computing Machinery (ACM). - 2475-1421. ; 7:OOPSLA2, s. 1363-1393
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Tidskriftsartikel (refereegranskat)abstract
- Verona is a concurrent object-oriented programming language that organises all the objects in a program into a forest of isolated regions. Memory is managed locally for each region, so programmers can control a program's memory use by adjusting objects' partition into regions, and by setting each region's memory management strategy. A thread can only mutate (allocate, deallocate) objects within one active region---its "window of mutability". Memory management costs are localised to the active region, ensuring overheads can be predicted and controlled. Moving the mutability window between regions is explicit, so code can be executed wherever it is required, yet programs remain in control of memory use. An ownership type system based on reference capabilities enforces region isolation, controlling aliasing within and between regions, yet supporting objects moving between regions and threads. Data accesses never need expensive atomic operations, and are always thread-safe.
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| 2. |
- Castegren, Elias, Doktor, 1987-, et al.
(författare)
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Encore : Coda
- 2023
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Ingår i: Active Object Languages. - : Springer Nature.
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Bokkapitel (refereegranskat)abstract
- Encore is a programming language that was developed between 2014 and 2019. Encore was designed following the principle of inversion of defaults: computations are concurrent (rather than sequential) by default; data is isolated (rather than freely sharable) by default. The language worked as a seedbed for a large number of research ideas aimed at making programming with active objects safe, expressive and efficient.Encore allows active objects to share data but statically ensures the absence of data races and allows fully concurrent garbage collection. Active objects can synchronize using first-class futures, which are also used to delegate and coalesce computations across active objects. The type system also supports orchestration of intra-object parallelism, expressed using composable units of computation. Active objects which see a lot of traffic can turn themselves into passive objects protected by lock-free synchronization mechanisms to avoid performance bottle-necks, while still facilitating safe sharing and concurrent garbage collection.This paper gives an overview of these features of Encore, reflecting on lessons learned from trying to fit all of these research ideas into a single language.
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| 3. |
- Palmkvist, Viktor, et al.
(författare)
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Statically Resolvable Ambiguity
- 2023
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Ingår i: Proceedings of the ACM on Programming Languages. - : ACM Digital Library. - 2475-1421. ; 7:POPL, s. 1686-1712
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Tidskriftsartikel (refereegranskat)abstract
- Traditionally, a grammar defining the syntax of a programming language is typically both context free and unambiguous. However, recent work suggests that an attractive alternative is to use ambiguous grammars,thus postponing the task of resolving the ambiguity to the end user. If all programs accepted by an ambiguous grammar can be rewritten unambiguously, then the parser for the grammar is said to be resolvably ambiguous. Guaranteeing resolvable ambiguity statically---for all programs---is hard, where previous work only solves it partially using techniques based on property-based testing. In this paper, we present the first efficient, practical, and proven correct solution to the statically resolvable ambiguity problem. Our approach introduces several key ideas, including splittable productions, operator sequences, and the concept of a grouper that works in tandem with a standard parser. We prove static resolvability using a Coq mechanization and demonstrate its efficiency and practical applicability by implementing and integrating resolvable ambiguity into an essential part of the standard OCaml parser.
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