until -package:numeric-prelude -package:base-prelude -package:distribution-opensuse -package:extra -package:foundation -package:basic-prelude -package:language-bash -package:ghc -package:free -package:yesod-paginator 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.