bound at entry of the goal, otherwise its value is false.
This implies that the variable first appears in this goal or a previous
appearance was in a negation (\+/1)
or a different branch of a disjunction.
singleton(Bool) Bool has the value
name(Name) True when variable appears with the given name in the source.
true if the variable is a
syntactic singleton in the term it appears in. Note that this
tests that the variable appears exactly once in the term being expanded
without making any claim on the syntax of the variable. Variables that
appear only once in multiple branches are not singletons
according to this property. Future implementations may improve on that.
4.3.1.1 Program transformation with source layout info
This sections documents extended versions of the program transformation predicates that also transform the source layout information. Extended layout information is currently processed, but unused. Future versions will use for the following enhancements:
- More precise locations of warnings and errors
- More reliable setting of breakpoints
- More reliable source layout information in the graphical debugger.