\definefontfeature[condensed][extend=0.9]25. Mai 2016 um 09:44
I implemented it by redefining \tt:
\definecharacterkerning[tight][factor=-.075]
\let\oldtt=\tt
\def\tt{\setcharacterkerning[tight]\oldtt}
However, I find this a bit of a kludge. But opinions may differ, of course.
Can this be done in a more general way? For example by setting some font feature?