until -package:numeric-prelude -package:yesod-paginator -package:prelude-compat -package:numhask -is:exact -package:snap-core -package:llvm-hs-pure -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.