until -package:numeric-prelude -package:yesod-paginator -package:prelude-compat -package:numhask -package:base -package:ghc-lib-parser -package:Cabal -package:intro -package:faktory -package:netwire 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.