until -package:numeric-prelude -package:util -package:xmonad-contrib -package:base-compat -package:rebase -package:numhask -package:intro -package:sparse-linear-algebra -package:prelude-compat -package:faktory 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.