actually it's not really difficult to add something like a s/\t/    /g to Good Intentions: Wikisyntax for the Monastery

The function exclude must be called with a 4th argument untabify in the line with text = exclude(text,/<(c|code)>[^]*?<\/\1>/g,"code",untabify);

If defined apply the callback to substring = transform(substring) before exclusions.push( [placeholder,substring] ); is done.

like this users can do personal adjustments to the way the transformation is done (not everyone wants 4 spaces for tab) in untabify()

Just documenting it for future implementation if a real demand rises.