until -package:numeric-prelude -package:util -package:xmonad-contrib -package:base-compat -package:streaming -package:numhask -package:protolude -package:cabal-install-solver -package:extra -package:linear-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.