My papers accessible in electronic form (last updated June 16-th 2004)

Kollár Ján: Towards Adaptive Text Processing, Acta Electrotechnica et Informatica, 3, 2, 2003, pp. 32-39, ISSN 1335-8243 pdf

Keywords: Text processing, typesetting, LaTeX, open systems, syntax driven editing, text generalization, context-free languages, LL(1) parsing
Abstract: A method of adaptive text processing presented in this paper exploits typesetting system LaTeX. Essentially, the goal is to prepare correct LaTeX source files without any knowledge of LaTeX command, using the production tool, being currently developed - an adaptive text editor (ATE). ATE is an open language system. Its text source files consists of hidden, visible and modifiable text areas that are terminal symbols of a language, which is a subset of LaTeX. LL(1) grammar of this language is defined incrementally. The defined grammar is a part of ATE scheme.

Kollár Ján: Partial Monadic Approach in Process Functional Language, Acta Electrotechnica et Informatica, 3, 1, 2003, pp. 36-42, ISSN 1335-8243 pdf
Keywords: Programming paradigms, imperative functional programming, aspect oriented programming, implementation principles, programming environments, control driven dataflow, referential transparency, side effects
Abstract: This paper is devoted to manipulating the state in process functional language (PFL) using monadic approach [13,19], preserving at the same time the visibility of memory cells. Instead of exploiting just pure functional expressions, as it is done in Haskell, balanced binding of functional and state aspects of computation in PFL using monads is presented. Monadic approach in PFL is partial in the sense that it may be exploited at any hierarchical level of computation, concentrating to the points in which state manipulation and pure functional evaluation are switched. From this point of view, this paper contributes to a systematic joining of function and state aspects of computation.

Kollár Ján, Porubän Jaroslav, Václavík Peter: The Classification of Programming Environments, Acta Universitatis Matthiae Belii, 10, 2003, pp. 51-64, ISBN 80-8055-662-8 pdf
Keywords: Programming paradigms, applicative programming, process functional programming, explicit and implicit environments, object and modular environments, environmental application, referential transparency, side effects
Abstract: A process functional paradigm prevents the use of assignments in programs, at the same time providing full power of both functional and imperative languages to a programmer. PFL - an experimental process functional language, originally developed as a programming language, seems to be promising to integrate the implementation requirements for any language aimed to von Neumann computer architectures. As we hope, PFL may serve as a unified implementation language in the future. That is why the formalized definitions of environments presented in this paper are useful and constructive for further development of PFL as a minimal superset of programming languages currently being used in a practice.

Kollár Ján: Imperative Expressions using Implicit Environments, Proc of ECI’2002, the 5-th Int. Scient. Conf. on Electronic Computers and Informatics, Herľany, Oct. 10-11, Košice, Slovakia, Department of Computers and Informatics FEII TU Košice, 2002, pp. 86-91, ISBN 80-7099-879-2 pdf
Keywords: implicit variable environment, visible memory cells, stateful functional evaluation
Abstract: In PFL - an experimental process functional programming language the imperative computation and the functional evaluation are clearly separated in a well-balanced manner. Neither environment variables nor assignments are used in PFL expressions that still manipulate the state using both explicit and implicit environments. In this way PFL extends to both imperative and functional languages, preserving the ability for reasoning about the programs and systems in terms of expressions. In this paper we concentrate to expressing the imperative programs in a purely functional manner using just implicit environments, which is semantically equivalent to that used in imperative functional languages. However, the implicit environment in PFL is visible, providing the strong feedback about the implementation to a user.

Kollár Ján: Implementation of Join Points and Advices using Process Functional Language, Analele Universitatii din Oradea, Proc. of the 7’th Scientific Conference with International participation EMES’03 Engineering of Modern Electric Systems, May 29-31, 2003, Felix Spa-Oradea, University of Oradea, Romania, 2003, pp. 93-98, ISSN 1223-2106 pdf
Keywords: Aspect oriented programming, process functional language, aspect language implementation
Abstract: Aspect oriented programming is a new programming methodology based on separating concerns (aspects) of computation, describing them separately in the form of advices that are applied in clearly selected set of points of a program using pointcut designators. In this paper we will show an opportunity for implementation of crosscutting concept of aspect oriented programming using PFL - a process functional programming language. We will concentrate on join points and advices, using simple example.

Kollár Ján, Porubän Jaroslav, Václavík Peter, Vidiščak Miroslav: Lazy State Evaluation of Process Functional Programs, Proceedings of the Conference “Information Systems Modelling” ISM’02, Rožnov pod Radhoštěm, April 22-24, Ostrava, MARQ, 2002, ACTA MOSIS, 87, pp. 165-172, ISBN 80-85988-70-4 pdf
Keywords: process functional language, imperative functional programming, lazy state evaluation, environment variables, monads, state transformers, Haskell
Abstract: The state of a system is expressed using PFL - a process functional language in an easily understandable manner. Coming out from monad and state transformers theory we define our concept of PFL variable environment. Then we introduce the style in which stateful systems are described using monads in pure lazy functional language Haskell. Finally, we describe briefly our approach to lazy state manipulation in PFL, as an inevitable basis for evaluating the efficiency of implementation of PFL for both sequential and parallel environments.

Kollár Ján: Unified Approach to Environments in a Process Functional Programming Language, Computers and Informatics, 22, 5, 2003, pp. 439-456, ISSN 1335-9150 pdf
Keywords: Programming paradigms, implementation principles, explicit and implicit environments, environmental application, control driven dataflow, referential transparency, side effects
Abstract: A process functional paradigm is based on applications of processes and functions instead of assignments. The imperative computation and the functional evaluation are clearly separated in a well-balanced manner, providing the strong feedback about the implementation to a user. In this paper we present the unified approach to explicit and implicit environments in PFL - an experimental process functional language, as a uniform basis for approved implementation extensible by additional specification. PFL environmental concept is the generalized implementation substance, which can be found in many programming languages exploiting the large variety of programming paradigms. Environment variables do not occur in expressions, being still visible to a programmer either in PFL textual form or in an equivalent form of control driven data flow graphs. The approach is promising for reasoning about the functional correctness and predicting the behavior of systems.

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