I've thought several times of removing sem in favor of filt. As features, they are very similar but filt is usually cleaner. If I don't see a compelling use case for actions soon I may indeed remove them. This would simplify the interface considerably.
Just between us, filt is actually an analogue to Haskell's monadic lift operator. They're even anagrams! (this happened by accident.)
Okay, I've since ported the Arki wikiformat parser to use filt instead of sem. Removing 'actions would reduce slightly the memory consumption of treeparse.
