until -package:numeric-prelude -package:yesod-paginator -package:prelude-compat -package:numhask -package:clash-prelude -package:protolude -package:ghc -package:singletons-base package:dunai -is:exact
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.