until -package:numeric-prelude -package:streaming -package:yesod-paginator -package:Cabal -package:elerea -package:hledger-web -package:rebase -package:utility-ht -package:hosc -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.