It is for BaseX, take a look at [1]. There is also an elvis operator on the same wiki page. Personally I don't like to deviate from specifications so I try to avoid it.

[1] - http://docs.basex.org/wiki/XQuery_Extensions#If_Without_Else

On 2/18/19 4:19 PM, Giuseppe G. A. Celano wrote:

Hi,

I see that in BaseX 9.1.2 an expression such as "if (3) then 4 " does not raise an error, even if the "else" part is missing. Is this correct?

Ciao,

Giuseppe

Best,

George