Structured Data

ACTA UNIVERSITATIS

UPSALIENSIS UPPSALA

2018

Digital Comprehensive Summaries of Uppsala Dissertations

from the Faculty of Science and Technology

1749

Structured Data

STEPHAN BRANDAUER

ISSN 1651-6214 ISBN 978-91-513-0515-8 urn:nbn:se:uu:diva-366932

Dissertation presented at Uppsala University to be publicly examined in Room 2446, Institutionen för informationsteknologi, Polacksbacken, Lägerhyddsvägen 2, Uppsala, Wednesday, 23 January 2019 at 13:15 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Professor Doug Lea (State University of New York at Oswego).

Abstract

Brandauer, S. 2018. Structured Data. Digital Comprehensive Summaries of Uppsala

Dissertations from the Faculty of Science and Technology 1749. 85 pp. Uppsala: Acta

Universitatis Upsaliensis. ISBN 978-91-513-0515-8.

References are a programming language construct that lets a programmer access a datum invariant of its location.

References permit aliasing -- several references to the same object, effectively making a single object accessible through different names (or paths). Aliasing, especially of mutable data, is both a blessing and a curse: when used correctly, it can make a programmer's life easier; when used incorrectly, for example through accidental aliases that the programmer is unaware of, aliasing can lead to hard to find bugs, and hard to verify programs.

Aliases allow us to build efficient data structures by connecting objects together, making them immediately reachable. Aliases are at the heart of many useful programming idioms. But with great power comes great responsibility: unless a programmer carefully manages aliases in a program, aliases propagate changes and make parts of a program's memory change seemingly for no reason. Additionally, such bugs are very easy to make but very hard to track down.

This thesis presents an overview of techniques for controlling how, when and if data can be aliased, as well as how and if data can be mutated. Additionally, it presents three different projects aimed at conserving the blessings, but reducing the curses. The first project is disjointness domains, a type system for expressing intended aliasing in a fine-grained manner so that aliasing will not be unexpected; the second project is Spencer, a tool to flexibly and precisely analyse the use of aliasing in programs to improve our understanding of how aliasing of mutable data is used in practise; and the third project is c flat, an approach for implementing high-level collection data structures using a richer reference construct that reduces aliasing problems but still retains many of aliasing's benefits.

Keywords: Aliasing, mutable state, imperative, programming, programming languages. Stephan Brandauer, Department of Information Technology, Division of Computing Science, Box 337, Uppsala University, SE-75105 Uppsala, Sweden.

© Stephan Brandauer 2018 ISSN 1651-6214

ISBN 978-91-513-0515-8

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