Hello, I use to lurk around here without chiming in, so pardon my intrusion :) I haven't followed the discussions of the mentioned SRFIs; maybe I'm missing some important pieces. > I am still waiting for empirical evidence that sequences like (list > (eof-object) ...) actually matter to anyone. Wondering whether it does matter to someone or not is not in my view a good criterion to cut corners. And excluding a possibly useful input value for no good reason isn't a _Good Thing_(TM). Might as well say that the identity function doesn't matter to anyone because it doesn't do anything. If I have a list of ports `l` and want to read the contents of all of them, `(map (cute read-string #f <>) l)` is one "obvious" way to go. Another probably better example is #f, although not related to generators & whatnot, which is commonly used as the "null value". Except when it is a valid input or output value. And that's why `maybe` from SRFI 189 is useful. siiky