Tag without argument?

[ondra-novak]

Is it possible to have tag without arguments? for example ["f"].

How this tag is indexed and how forge a filter for REQ to find events with this tag?

[fiatjaf]

It is possible, but it probably won't be indexed.

[ondra-novak]

Ok.
That's just what I was hoping would be possible with a filter written like that: "#f":[]

[alexgleason]

You want presence and absence filters. #523

[ondra-novak]

It makes sense to me that "#f":[] means test for the existence of a particular tag, since ⌷ is always fulfilled (like looking for an empty string in a string)

An alternative would be to use null to test for the absence of a tag.

This would deserve a new NIP

[alexgleason]

We can't use null in the filter because that's a breaking change. See my comment here: #523 (comment)

[ondra-novak]

Oh ok, some platforms are not that flexible. I'll wait until this is resolved

Thank you, marking this answered