until -package:numeric-prelude -package:yesod-paginator -package:prelude-compat -package:numhask -package:hledger-web -package:free -package:intro -package:clash-prelude -package:elerea 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.