I wrote:
It's not a good idea for a basic time library to introduce possible crashes. At least you should provide an alternative safe interface. Similarly for toEnum.
Chris Heller wrote:
are you suggesting something like doing modulo arithmetic rather than calling error on undefined values?
Well, the standard "safe interface" would just wrap the return type in Maybe, like fromGregorianValid does. Then you might use it something like this: maybe [] (map moment . take 5 . recurBy 10 [] . Daily) maybeStartDate Using modulo arithmetic for toEnum would indeed make the function safe, but I'm not sure that would give the results that users are expecting. For the start date of a recurrence, though, you are right that you might be able to do better than just using Maybe. Suppose you had a function that rounds an invalid Gregorian date forward to the nearest valid date. Then a user that asks for a recurrence starting with, say, Feb. 30 would get dates starting at the beginning of March, which is probably what was intended. Regards, Yitz