Monads have taken the world by storm, and are supported by
do-notation (at least in Haskell). Programmers are increasingly waking up to the usefulness and ubiquity of
Applicatives, but they have so far been hampered by the absence of supporting notation. In this paper we show how to re-use the very same
do-notation to work for
Applicatives as well, providing efficiency benefits for some types that are both
Applicative, and syntactic convenience for those that are merely
Applicative. The result is fully implemented in GHC, and is in use at Facebook to make it easy to write highly-parallel queries in a distributed system.