until -package:numeric-prelude -package:util -package:hedgehog -package:yesod-paginator -package:elerea -package:mixed-types-num -package:snap-core -package:free -package:hledger-web -package:extra -package:singletons-base package:dunai
Similar to Yampa's delayed switching. Loses a b in case of an
exception.
Run the first
msf until the second one produces
True
from the output of the first.