until -package:numeric-prelude -package:streaming -package:yesod-paginator -package:Cabal -package:classy-prelude -package:mixed-types-num -package:ghc -package:extra -package:base-prelude -package:scalpel-core 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.