I'm curious about the performance overhead of this vs using traditional syntax with named variables. Looking over the gem, the code is quite terse, but it depends on method_missing, which is notoriously slow. The danger with an abstraction like this is that it can make performance problems difficult to identify since it looks so much like a built-in operator.

I also agree with stuffihavemade in that I don't actually find

   (&X.method(bar))

any more clear than

   { |x| x.method(bar) }