until -package:numeric-prelude -package:util -package:xmonad-contrib -package:LambdaHack -package:prelude-compat -package:elerea -package:basic-prelude -package:hosc -package:Cabal-syntax -package:base-compat -package:foundation 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.