Whew! <- The sigh of relief after reading comments here and realizing that I'm not the only one preferring the standard style of writing Python instead of this "functional"(??) style...
I get that Optional return values can force the programmer to handle errors without resorting to exceptions, but I can't help but wonder whether the first example with all those `bind_optional` ... is just Objective-C's nil messaging in fancy disguise...
FWIW in Objective C this is exactly what one writes (even if those functions can return nil):
credit = user.get_balance().credit_amount()
if credit > 0:
discount_program = choose_discount(credit)