until -package:numeric-prelude -package:streaming -package:foundation -package:hosc -package:faktory -package:singletons-base -package:xmonad-contrib -package:cabal-install-solver -package:ghc 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.