until -package:numeric-prelude -package:base-prelude -package:hosc -package:numhask -package:util -package:faktory -package:streaming -package:selective -package:LambdaHack -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.