Syntax and Semantics of Babel-17

We present Babel-17, the first programming language for purely functional structured programming (PFSP). Earlier work illustrated PFSP in the framework of a toy research language. Babel-17 takes this earlier work to a new level by showing how PFSP can be combined with pattern matching, object oriented programming, and features like concurrency, lazy evaluation, memoization and support for lenses

Separating Concerns in Programming: Data, Control and Actions

A multi-paradigm language provides an opportunity to a user for exploiting more programming methodologies. It simplifies the language syntax, and extends the application areas by the extended semantics. That is why multi-paradigm languages can align a problem in wider application areas and more flexibly than that based on a single paradigm. In this paper, we present the idea of separating three essential concerns of programming currently being implemented in PFL -- a process functional language. We separate data, control, and actions by the definition of a purely control structure. Then, by the structured application of a structure of actions to a purely control structure, we will express the computation of activated actions in a structured way, considering explicitly defined synchronization in computation

Composing graphical user interfaces in a purely functional language

This thesis is about building interactive graphical user interfaces in a compositional manner. Graphical user interface application hold out the promise of providing users with an interactive, graphical medium by which they can carry out tasks more effectively and conveniently. The application aids the user to solve some task. Conceptually, the user is in charge of the graphical medium, controlling the order and the rate at which individual actions are performed. This user-centred nature of graphical user interfaces has considerable ramifications for how software is structured. Since the application now services the user rather than the other way around, it has to be capable of responding to the user's actions when and in whatever order they might occur. This transfer of overall control towards the user places heavy burden on programming systems, a burden that many systems don't support too well. Why? Because the application now has to be structured so that it is responsive to whatever action the user may perform at any time. The main contribution of this thesis is to present a compositional approach to constructing graphical user interface applications in a purely functional programming language The thesis is concerned with the software techniques used to program graphical user interface applications, and not directly with their design. A starting point for the work presented here was to examine whether an approach based on functional programming could improve how graphical user interfaces are built. Functional programming languages, and Haskell in particular, contain a number of distinctive features such as higher-order functions, polymorphic type systems, lazy evaluation, and systematic overloading, that together pack quite a punch, at least according to proponents of these languages. A secondary contribution of this thesis is to present a compositional user interface framework called Haggis, which makes good use of current functional programming techniques. The thesis evaluates the properties of this framework by comparing it to existing systems

Type-Directed Program Transformations for the Working Functional Programmer

We present preliminary research on Deuce+, a set of tools integrating plain text editing with structural manipulation that brings the power of expressive and extensible type-directed program transformations to everyday, working programmers without a background in computer science or mathematical theory. Deuce+ comprises three components: (i) a novel set of type-directed program transformations, (ii) support for syntax constraints for specifying "code style sheets" as a means of flexibly ensuring the consistency of both the concrete and abstract syntax of the output of program transformations, and (iii) a domain-specific language for specifying program transformations that can operate at a high level on the abstract (and/or concrete) syntax tree of a program and interface with syntax constraints to expose end-user options and alleviate tedious and potentially mutually inconsistent style choices. Currently, Deuce+ is in the design phase of development, and discovering the right usability choices for the system is of the highest priority

Can Computer Algebra be Liberated from its Algebraic Yoke ?

So far, the scope of computer algebra has been needlessly restricted to exact algebraic methods. Its possible extension to approximate analytical methods is discussed. The entangled roles of functional analysis and symbolic programming, especially the functional and transformational paradigms, are put forward. In the future, algebraic algorithms could constitute the core of extended symbolic manipulation systems including primitives for symbolic approximations.Comment: 8 pages, 2-column presentation, 2 figure