There are many situations where we want infinite recursion. A simple example is a server: def serve(request): response = process(request) socke

There are many situations where we want infinite recursion. A simple example is a server: def serve(request): response = process(request) socket.send(response) serve(socket.receive()) The same thing applies to anything which 'handles events', including servers, games, GUIs, CLIs, etc. In general, any time we might write a "main loop" like: foo = lambda z: .... bar = lambda x: .... baz = lambda y: .... def main(): z = init while true: x = foo(z) y = bar(x) z = baz(y) This is equivalent to having each step perform a tail-call to the next one: foo = lambda z: bar(....) bar = lambda x: baz(....) baz = lambda y: foo(....) main = lambda : foo(init) The latter form has better encapsulation, requires no mutable state, doesn't have stale/out-of-date variables, etc. The fact that infinite recursion is seen as a bug, yet "while true:" loops are common, is a symptom of this negative feedback loop which keeps people from learning and using recursive solutions.