How can I use a 1-argument function in an "ANY"/"ALL" query?
You can use the first function with ANY but you have to have a valid syntax as you found out (&lt;expression&gt; &lt;**operator**&gt; ANY ...). So the following would work (the "trick" piece is to use unnest() whild unfolds the array into rows):

SELECT true = ANY (select myfun(x) from unnest(ARRAY['test', 'world']) as x) ;


or the more compact:

SELECT true = ANY (select myfun(unnest(ARRAY['tt', 'foo']))) ;