It appears to be called "backward pipe" compared to "forward pipe":

* [Why use a Backward Pipe Operator instead of Function Chaining?](http://stackoverflow.com/questions/5443805/why-use-a-backward-pipe-operator-instead-of-function-chaining/5444278#5444278)

It seems to be the perfect syntactic sugar for our frequent undo/redo uses like this where we are passing a fun as the last argument and the parens are awkward.