We give a brief account of the discoveries of continuations and related concepts by, A. Van Wijngaarden , A. W. Mazurkiewicz , F. L. Morris , C. P. Wadsworth , J. H. Morris , M. J. Fischer , and S. K. Abdali.

Research into providing support for long term data in lazy functional programming systems is presented in this thesis. The motivation for this work has been to reap the benefits of integrating lazy functional programming languages and persistence. The benefits are . the programmer need not write code to support long term data since this is provided as part of the programming system . persistent data can be used in a type safe way since the programming language type system applies to data with the whole range of persistence . the benefits of lazy evaluation are extended to the full lifetime of a data value. Whilst data is reachable, any evaluation performed on the data persists. A data value changes monotonically from an unevaluated state towards a completely evaluated state over time. . interactive data intensive applications such as functional databases can be developed. These benefits are realised by the development of models for persistence in lazy functional programming systems. Tw...

Regular expressions with back referencing have been used in a variety of software products in common use, such as Emacs and Perl, for many years. In these products, regular expressions have been extended with a naming construct. If a subexpression is named by some variable, whenever this subexpression matches some string, that string is assigned to the variable. Later occurrences of the same variable will then match the string assigned to it. This construction greatly increases the power of regular expressions and is useful in text searching as well as in text substitution in large documents. We study the nested usage of this operator, and prove that the power of the expressions increase with the number of nested levels that are allowed. 1 Introduction Back referencing has been used for many years. Constructs of this type show up in Snobol [4] and in the Unix command grep [7]. It is also available in popular editors such as Emacs [8] and programming languages such as Perl [9]. However...

This manuscript presents a survey of the theoretical foundations of regular expres- sions and text editors. A thourough introduction to the subjects of symbols, lan- guages, grammars, regular expressions, finite automata, character sets (Unicode), pattern matching, and the inner and outer workings of a text editor is given. The knowledge contained in this survey is then put to good use in presenting a method of compiling regular expressions into efficient finite automata that are well suited for pattern matching tasks in a text editor. The usefulness of pattern matching inside a text editor is also shown, by describing the command sets of modern text editors, such as sam and vim. Finally, a pattern-matching library has been written that can be used in, for example, a text editor. A library implementing an efficient data structure for rep- resenting sequences has also been written. Both these libraries have been used to create an example text editor that uses the pattern-matching library in implement- ing its command set and the data-structure library in implementing its buffering strategy. All pieces of software have been documented using a literate programming style of writing and are included in this manuscript for reference.

An extensible multilingual library for accessing wordnets in different languages