Instantiation Errors

An instantiation error occurs when a predicate or command is called with one of its input arguments insufficiently instantiated.

The exception code associated with an instantiation error is

     instantiation_error(Goal, ArgNo)

ArgNo is a non-negative integer indicating which argument caused the problem. ArgNo=0 means that the problem could not be localized to a single argument. , atom_chars/2, functor/3 etc., which allow alternative instantiation patterns. Maybe this will be fixed but lets leave it vague for now. -DLB}

Note that the ArgNoth argument of Goal might well be a non-variable: the error is in that argument. For example, the goal

     X is Y+1

where Y is uninstantiated raises the exception

     instantiation_error(_2298 is _2301+1,2)

because the second argument to is/2 contains a variable.