until -package:numeric-prelude -package:base-prelude -package:hosc -package:numhask -package:conferer -package:monad-loops -package:protolude -package:base-compat -package:xmonad-contrib -is:exact 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.