Enveloping Implicit Assumptions of Intrusive Data Structures within Ownership Type System

Confinement properties impose a structure on object graphs which can be used to enforce encapsulation properties. From a practical point of view, encapsulation is essential for building secure object-oriented systems as security requires that the interface between trusted and untrusted components of a system be clearly delineated and restricted to the smallest possible set of operations and data structures. This paper investigates the notion of package-level confinement and proposes a type system that enforces this notion for a call-by-value object calculus as well as a generic extension thereof. We give a proof of soundness of this type system, and establish links between this work and related research in language-based security.

Download Full-text

Featherweight generic confinement

Journal of Functional Programming ◽

10.1017/s0956796806006125 ◽

2006 ◽

Vol 16 (6) ◽

pp. 793-811 ◽

Cited By ~ 7

Author(s):

ALEX POTANIN ◽

JAMES NOBLE ◽

DAVE CLARKE ◽

ROBERT BIDDLE

Keyword(s):

Programming Languages ◽

Ad Hoc ◽

Type System ◽

Type Systems ◽

General Purpose ◽

Ownership Type ◽

Essential Change ◽

Polymorphic Type ◽

Syntactic Restrictions

Existing approaches to object encapsulation either rely on ad hoc syntactic restrictions or require the use of specialised type systems. Syntactic restrictions are difficult to scale and to prove correct, while specialised type systems require extensive changes to programming languages. We demonstrate that confinement can be enforced cheaply in Featherweight Generic Java, with no essential change to the underlying language or type system. This result demonstrates that polymorphic type parameters can simultaneously act as ownership parameters and should facilitate the adoption of confinement and ownership type systems in general-purpose programming languages.

Download Full-text

Data Structures in Leelus Programming Language: A Research

10.14293/s2199-1006.1.sor-.ppbbney.v1 ◽

2021 ◽

Author(s):

Frank Appiah

Keyword(s):

Data Structure ◽

Programming Language ◽

Data Structures ◽

Type System

This is a research on data structures using pointer declaration for array dimensional type of representation in variable declaration. In this research, I will describe type array, term array and value array drawn from both data structure and type system.

Download Full-text

Intensional polymorphism in type-erasure semantics

Journal of Functional Programming ◽

10.1017/s0956796801004282 ◽

2002 ◽

Vol 12 (6) ◽

pp. 567-600 ◽

Cited By ~ 20

Author(s):

KARL CRARY ◽

STEPHANIE WEIRICH ◽

GREG MORRISETT

Keyword(s):

Data Structures ◽

Garbage Collection ◽

Type System ◽

Implementation Techniques ◽

Run Time ◽

Closure Conversion ◽

Type Information ◽

Time Type

Intensional polymorphism, the ability to dispatch to different routines based on types at run time, enables a variety of advanced implementation techniques for polymorphic languages, including tag-free garbage collection, unboxed function arguments, polymorphic marshalling and attened data structures. To date, languages that support intensional polymorphism have required a type-passing (as opposed to type-erasure) interpretation where types are constructed and passed to polymorphic functions at run time. Unfortunately, type-passing suffers from a number of drawbacks: it requires duplication of run-time constructs at the term and type levels, it prevents abstraction, and it severely complicates polymorphic closure conversion. We present a type-theoretic framework that supports intensional polymorphism, but avoids many of the disadvantages of type passing. In our approach, run-time type information is represented by ordinary terms. This avoids the duplication problem, allows us to recover abstraction, and avoids complications with closure conversion. In addition, our type system provides another improvement in expressiveness; it allows unknown types to be refined in place, thereby avoiding certain beta-expansions required by other frameworks.

Download Full-text

Reachability types: tracking aliasing and separation in higher-order functional programs

Proceedings of the ACM on Programming Languages ◽

10.1145/3485516 ◽

2021 ◽

Vol 5 (OOPSLA) ◽

pp. 1-32

Author(s):

Yuyan Bao ◽

Guannan Wei ◽

Oliver Bračevac ◽

Yuxuan Jiang ◽

Qiyang He ◽

...

Keyword(s):

Functional Programming ◽

Type System ◽

Type Systems ◽

Higher Order ◽

Ownership Type ◽

Ownership Transfer ◽

Reachability Sets ◽

Programming Patterns ◽

New Type ◽

Higher Order Functions

Ownership type systems, based on the idea of enforcing unique access paths, have been primarily focused on objects and top-level classes. However, existing models do not as readily reflect the finer aspects of nested lexical scopes, capturing, or escaping closures in higher-order functional programming patterns, which are increasingly adopted even in mainstream object-oriented languages. We present a new type system, λ * , which enables expressive ownership-style reasoning across higher-order functions. It tracks sharing and separation through reachability sets, and layers additional mechanisms for selectively enforcing uniqueness on top of it. Based on reachability sets, we extend the type system with an expressive flow-sensitive effect system, which enables flavors of move semantics and ownership transfer. In addition, we present several case studies and extensions, including applications to capabilities for algebraic effects, one-shot continuations, and safe parallelization.

Download Full-text

Type-based analysis of logarithmic amortised complexity

Mathematical Structures in Computer Science ◽

10.1017/s0960129521000232 ◽

2021 ◽

pp. 1-33

Author(s):

Martin Hofmann ◽

Lorenz Leutgeb ◽

David Obwaller ◽

Georg Moser ◽

Florian Zuleger

Keyword(s):

Data Structures ◽

Type System ◽

Automated Analysis ◽

Logarithmic Potential ◽

Potential Functions ◽

Resource Analysis

Abstract We introduce a novel amortised resource analysis couched in a type-and-effect system. Our analysis is formulated in terms of the physicist’s method of amortised analysis and is potentialbased. The type system makes use of logarithmic potential functions and is the first such system to exhibit logarithmic amortised complexity. With our approach, we target the automated analysis of self-adjusting data structures, like splay trees, which so far have only manually been analysed in the literature. In particular, we have implemented a semi-automated prototype, which successfully analyses the zig-zig case of splaying, once the type annotations are fixed.

Download Full-text

Ultrastructural characteristics of sporidia of Ustilago

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155906 ◽

1989 ◽

Vol 47 ◽

pp. 786-787

Author(s):

Patricia N. Hackney

Keyword(s):

Electron Microscope ◽

Type System ◽

Tube Formation ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

University Of Wisconsin ◽

Transmission Electron ◽

Ustilago Hordei ◽

Silene Alba ◽

The University

Ustilago hordei and Ustilago violacea are yeast-like basidiomycete pathogens ofHordeum vulgare and Silene alba respectively. The mating type system in both species of Ustilago is bipolar, with alleles, A,a, (U.hordei) and a1, a2 (U.violacea) at a single locus. Haploid sporidia maintain the asexual phase by budding, while the sexual phase is initiated by conjugation tube formation between the mating types during budding and conjugation.For observation of budding, sporidia were prepared by culturing the four types on YEG (yeast extract glucose) broth for 24 hours. After centrifugation at 5000g cells were either left unmated or mated in a1/a2,A/a combinations. The sporidia were then mixed 1:1 with 4% agar and the resulting 1mm cubes fixed in 8% gluteraldehyde and post fixed in osmium tetroxide. After dehydration and embedding cubes were thin sectioned with a LKB ultratome and photographed in a Zeiss 9s transmission electron microscope or in an AE1 electron microscope of MK11 1MEV at the High Voltage Electron Microscopy Center of the University of Wisconsin-Madison.

Download Full-text