rebinding arrow notation

Section 8.3.5 of the documentation says: Arrow notation (see Section 8.9, “Arrow notation ”) uses whatever arr, (>>>), first, app, (|||) and loop functions are in scope. But unlike the other constructs, the types of these functions must match the Prelude types very closely. Details are in flux; if you want to use this, ask! I want to do this. Is there anything special I should know? Pete