GRAPHICAL DISPLAY OF COMPLEX INFORMATION WITHIN A PROLOG DEBUGGER
Date
1985-12-01
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Abstract
An interactive Prolog debugger, DEWLAP, is described. Output from the
debugger is in the form of graphical displays of both the derivation
tree and the parameters to procedure calls. The major advantage of
such displays is that they allow important information to be
displayed prominently and unimportant information to be shrunk so that
it is accessible but not distracting. Other advantages include the following:
the control flow in Prolog is clearly shown; the control context of a
particular call is readily determined; it is easy to find out whether
two uninstantiated variables are bound together; and very fine control is
possible over debugging and display options. A high-level graphics language
is provided to allow the user to tailor the graphical display of data
structures to particular applications. A number of issues raised by the
need to update such displays efficiently and to control their perceived
complexity are addressed. The DEWLAP system is implemented in Prolog
on relatively standard hardware with a central processor running Unix
and remote workstations with bitmapped displays and mice.
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Computer Science