until -package:numeric-prelude -package:yesod-paginator -package:prelude-compat -package:base-prelude -package:streaming -package:foundation -package:snap-core -package:hedgehog 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.