It should be easy to edit the existing code to add support for i18n, but there’s probably no way to make in generic (except for macros).

Yeah, that was basically it.

There’s no purpose really. It was more of “wonder if I can” and also nice way to learn custom literals.

I can actually define this in TCL:

% proc ifn't {cond cmds} {if {!$cond} {uplevel $cmds}}
% ifn't false {puts 12}
12
% ifn't true {puts 12}
%