But I don't see much benefit to having (<**>) let alone (<$$>), when they are easily defined by using flip. The other clutter of Applicative ((<*), (*>),...) can be motivated by performance concerns for certain applicative combinator parsers, but I'm not a big fan of them either.

While this is a valid concern with regards to <$$>, <**> cannot be defined in terms of flip as it swaps the order of the effects as well.

-Edward Kmett