I want to be able to concatenate strings with a separator between them, but such that the separator is only used for non-empty string, i.e. with separator " ", "Foo", "Bar", "" => "Foo Bar" "Foo", "", "Baz" => "Foo Baz" "Foo", "", "" => "Foo" the CONCAT and CONCATENATE functions don't offer this functionality (see also text/scalc/01/func_concat.html in the help docs).
https://help.libreoffice.org/latest/en-US/text/scalc/01/func_textjoin.html?DbPAR=CALC#bm_id581556228060864