until -package:numeric-prelude -package:streaming -package:yesod-paginator -package:Cabal -package:ghc -package:utility-ht -package:basic-prelude -package:ghc-lib-parser 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.