GEC: a Toolkit for Generic Rapid Prototyping of Type Safe Interactive Applications

Contains fulltext : 60461_pub.pdf (publisher's version ) (Open Access) Contains fulltext : 60461_pre.pdf (preprint version ) (Open Access)GUI programming is notoriously tedious. By using generic functions that create Graphical Editor Components (GECs), it becomes possible to define user interfaces without any knowledge of low level I/O handling. A GEC editor can automatically be derived for values of any (user-defined) monomorphic (first order) type. With an editor the application user can create new values of the type the editor is created for. In this way one obtains an editor for free for almost any type. Such a free editor may not look fancy, but one can change the default look by defining specialized versions of the generic function for certain types, e.g. representing buttons, pull-down menus and the like. Furthermore, with GECs the programmer can create an abstraction level separating the view type and the domain type completely. As a result, the programmer can easily make a library of suited graphical representations and freely choose which representation to use. Consequently, working with GECs a programmer can focus on the data type representing the user interaction instead of on the nasty graphical details. Editors can be easily combined to ensure that a change in one editor has effects on the contents of others. One can combine editors by hand or use an arrow library of editor combinators. It is even possible to create editors for higher order types which enables the creation of user interfaces in which functions can be typed in by the user or read from disk at run-time. In the latter case, functions are actually compiled functions that are dynamically linked into the running application. GECs are suited for rapid prototyping of real world applications, for teaching and for debugging. This paper focuses on the use of the GEC toolkit for functional programmers, only briefly explaining its inner workings and underlying principles.AFP 200