ProXT is a Prolog interface to the Motif widget set and the X Toolkit (Xt). Widgets are ready-made graphical components for building user-interfaces, for example, menus, dialog boxes, scroll bars and command buttons. The X Toolkit provides routines for creating and using such widgets. ProXT provides access from Prolog to all the widgets in Motif and to the Xt routines necessary for using the widgets.

ProXT permits the rapid development of user-interfaces with the Motif "look and feel". The interactive development environment of Prolog greatly shortens the edit-test-debug cycle. Individual files can be recompiled incrementally, avoiding the need to exit the application and re-link it. In addition, ProXT provides the programmer with a more logical view of the Motif widget set and reinforces its object-oriented nature.

Almost all of the predicates in ProXT are interfaced directly to functions from the underlying C interface. Also, there is a straightforward correspondence between the data structures used: for example ProXT expects a list where Xt expects an array. This makes it very easy to switch between writing Prolog code for ProXT and C code for Xt and Motif. In addition, ProXT can readily be used in conjunction with C code written for Motif and Xt.

ProXT is not available under Windows.