Hans E. Muller

Integrating the Scheme and C languages

Most implementations of Scheme (and other Lisp dialects) provide some facility for calling functions defined in ANSI C (or other popular languages) even if only to implement Scheme’s primitive operations. Some relatively sophisticated implementations provide access to non-Scheme data structures, Taking a Scheme-centered view, we will refer to these facilities as~oreign call-out, for both data and functions access. Scheme implementations may also provide ways for C code to use Scheme functions and data structures more or less directly. We will refer to this as~oreign call-in.

The use of multimethods and method combination in a CLOS based window interface

Solo is a portable window interface written in the Common Lisp Object System (CLOS) object-oriented programming language. Solo provides a virtual window machine which is targeted to a host window system by implementing a set of host window system specific classes and methods for Solos host window system driver protocol. The interface presented by Solo to an application insulates it from differences in the host window system, facilitating application portability. Solo distinguishes itself from other object-oriented window systems by exploiting certain features of CLOS. CLOS method combination simplifies initialization of windows while preserving easy extensibility of the basic classes. Generic dispatch on multiple arguments, a feature unique to CLOS, allows a simpler and more flexible input event dispatching protocol. A powerful event description language simplifies the specification of keyboard and mouse events. A prototype implementation runs on the server based XII and NeWS host systems, and on the frame buffer based Lucid Window Toolkit.

LispView: leverage through integration

Although Lisp was the host for many of the first graphical user interface (GUI) packages, popular activity in this area has shifted to more primitive but widely used languages such as C and C++. One explanation for this shift is that while Lisps strength in rapid prototyping and development led to the initial progress, it also tended to inspire an imperialist attitude: applications were often crafted exclusively in Lisp, even when part of the application could make use of an existing conventional language library. We believe the ideal way to construct a CommonLisp GUI package today is to integrate proven C libraries with an object-oriented Lisp framework.