Is this quite right? Sorry this is a bit vague/unclear, but what happens if you, say, call the reduction function, throw the result away and then call it again?

I ran this example through Clojure in let's write a transducer, and it plain doesn't work; I think the mapping given above works for all transducers that are actually valid, but I think the type definition allows for broken ones.

Again, I'm not sure & still learning, so please explain if I've gone wrong here.