Lisp Propulsion Laboratory log

Paolo Amoroso's weblog. Main interests: Lisp, astronomy (Moon), space exploration (Apollo and early manned programs)

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LISA debugging tip: check rules and facts for typos

Tuesday, September 20, 2005

This tip for debugging rule-based systems written with LISA (see also my notes) may seem trivial, but I have found it effective many times.

Here is the tip. If you get:

• errors about the wrong type for a predicate argument when evaluating/compiling a rule or asserting a fact, or
• a rule you are reasonably sure should fire fails to do so