Olaf Chitil

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Carlos Eduardo Cirilo

UFSCar - Federal University of São Carlos

David Seamon

Kansas State University

Remo Caponi

University of Cologne

Armando Marques-Guedes

UNL - New University of Lisbon

Birol Aygün

Yeditepe University

Fabio Cuzzolin

Oxford Brookes University

naveen noronha

Visvesvaraya Technological University

Sergio Soares

Universidade Federal de Pernambuco

Konstantin Läufer

Loyola University Chicago

A. Z. Hafez

University of Nottingham

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Papers by Olaf Chitil

Comprehending finite maps for algorithmic debugging of higher-order functional programs

by Thomas Davie and Olaf Chitil

Proceedings of the 10th international ACM SIGPLAN symposium on Principles and practice of declarative programming - PPDP '08, 2008

Testing and Tracing Lazy Functional Programs Using QuickCheck and Hat

Lecture Notes in Computer Science, 2003

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Observing Functional Logic Computations

by Olaf Chitil and Michael Hanus

Lecture Notes in Computer Science, 2004

A lightweight approach to debugging functional logic programs by observations is presented, imple... more A lightweight approach to debugging functional logic programs by observations is presented, implemented for the language Curry. The Curry Object Observation System (COOSy) comprises a portable library plus a viewing tool. A programmer can observe data structures and functions by annotating expressions in his program. The possibly partial values of observed expressions that are computed during program execution are recorded in a trace file, including information on non-deterministic choices and logical variables. A separate viewing tool displays the trace content. COOSy covers all aspects of modern functional logic multiparadigm languages such as lazy evaluation, higher order functions, non-deterministic search, logical variables, concurrency and constraints. Both use and implementation of COOSy are described.

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Combining algorithmic debugging and program slicing

by Olaf Chitil and Josep Silva

Proceedings of the 8th ACM SIGPLAN symposium on Principles and practice of declarative programming - PPDP '06, 2006

Currently, program slicing and algorithmic debugging are two of the most relevant debugging techn... more Currently, program slicing and algorithmic debugging are two of the most relevant debugging techniques for declarative languages. They help programmers to find bugs in a semiautomatic manner. On the one hand, program slicing is a technique to extract those program fragments that (potentially) affect the values computed at some point of interest. On the other hand, algorithmic debugging is able to locate a bug by automatically generating a series of questions and processing the programmer's answers. In this work, we show for functional languages how the combination of both techniques produces a more powerful debugging schema that reduces the number of questions that programmers must answer to locate a bug.

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Lazy Assertions

Lecture Notes in Computer Science, 2004

Monadic, Prompt Lazy Assertions in Haskell

Lecture Notes in Computer Science, 2007

Assertions test expected properties of run-time values with- out disrupting the normal computatio... more Assertions test expected properties of run-time values with- out disrupting the normal computation of a program. We present a li- brary for enriching Haskell programs with assertions. Expected proper- ties can be specified in a parser-combinator like language. The assertions are lazy: they do not force evaluation but only examine what is evaluated by the program. They are also prompt: assertion failure is reported as early as possible. The implementation is based on lazy observations and continuation-based coroutines.

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Transforming Haskell for Tracing

Lecture Notes in Computer Science, 2003

Abstract. Hat is a programmer's tool for generating a trace of a com-putation of a Haskell 9... more

Freja, Hat and Hood - A Comparative Evaluation of Three Systems for Tracing and Debugging Lazy Functional Programs

Lecture Notes in Computer Science, 2001

In this paper we compare three systems for tracing and de- bugging Haskell programs: Freja, Hat a... more In this paper we compare three systems for tracing and de- bugging Haskell programs: Freja, Hat and Hood. We evaluate their use- fulness in practice by applying them to a number of moderately complex programs in which errors had deliberately been introduced. We identify the strengths and weaknesses of each system and then form ideas on how the systems can

Multiple-View Tracing for Haskell: a New Hat

Different tracing systems for Haskell give different views of a program at work. In practice, sev... more Different tracing systems for Haskell give different views of a program at work. In practice, several views are complementary and can productively be used together. Until now each system has generated its own trace, containing only the information needed for its particular view. Here we present the design of a trace that can serve several views. The trace is generated and written to file as the computation proceeds. We have implemented both the generation of the trace and several different viewers.

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Linear, bounded, functional pretty-printing

by Olaf Chitil and S. Doaitse Swierstra

Journal of Functional Programming, 2009

We present two implementations of Oppen's pretty-printing algorithm in Haskell that meet the effi... more We present two implementations of Oppen's pretty-printing algorithm in Haskell that meet the efficiency of Oppen's imperative solution but have a simpler, clear structure. We start with an implementation that uses lazy evaluation to simulate two co-operating processes. Then we present an implementation that uses higher-order functions for delimited continuations to simulate co-routines with explicit scheduling.

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Structure and Properties of Traces for Functional Programs

Electronic Notes in Theoretical Computer Science, 2007

The tracer Hat records in a detailed trace the computation of a program written in the lazy funct... more The tracer Hat records in a detailed trace the computation of a program written in the lazy functional language Haskell. The trace can then be viewed in various ways to support program comprehension and debugging. The trace was named the augmented redex trail. Its structure was inspired by standard graph rewriting implementations of functional languages. Here we describe a model

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Freja, hat and hood-a comparative evaluation of three systems for tracing and debugging lazy functional programs

The lack of tools for tracing and debugging has deterred software developers from using functiona... more

A Pattern Logic for Lazy Assertions in Haskell

Algorithmic Debugging for Locally Defined Functions

Algorithmic Debugging with Cyclic Traces of Lazy Functional Programs

Monadic, Lazy Assertions in Haskell

Replacing unevaluated parts in the traces of functional programs

One right does make a wrong

by Thomas Davie and Olaf Chitil

Tracing and Debugging of Lazy Functional Programs-A Comparative Evaluation of Three Systems

In this paper we compare three systems for tracing and debugging Haskell programs: Freja, the Red... more In this paper we compare three systems for tracing and debugging Haskell programs: Freja, the Redex Trail System and Hood. We identify the similarities and differences of these systems and we evaluate their usefulness in practice by applying them to a number of small to medium programs in which errors had deliberately been introduced.

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Display of functional values for debugging

by Thomas Davie and Olaf Chitil

Comprehending finite maps for algorithmic debugging of higher-order functional programs

by Thomas Davie and Olaf Chitil

Proceedings of the 10th international ACM SIGPLAN symposium on Principles and practice of declarative programming - PPDP '08, 2008

Testing and Tracing Lazy Functional Programs Using QuickCheck and Hat

Lecture Notes in Computer Science, 2003

Download

Observing Functional Logic Computations

by Olaf Chitil and Michael Hanus

Lecture Notes in Computer Science, 2004