until -package:numeric-prelude -package:base-prelude -package:distribution-opensuse -package:Cabal -package:free -package:xmonad-contrib -package:sparse-linear-algebra -package:ghc-lib-parser -package:LambdaHack package:dunai -is:exact
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.