How to check optional variable bindings?

[mielvds]

When using ?__var, how can you check it's presence in SA? A BOUND(?__var) or BIND(?__var as ?var ). BOUND(?var) do not really work. I also get the path of the working directory bound to the variable, is that the default?

[enridaga]

Variable substitution happens before the query is evaluated. So, if the value is passed, BOUND would not work because it will apply to the value -- e.g. BOUND("some literal") would not make sense. If the variable is not substituted, it depends on where it is placed. If it is in a graph pattern, then it will be bound if the pattern is evaluated, and so on.

Can you provide an example of what you would like to do?