+let short_weekday = function
+ | 0 -> "Sun" | 1 -> "Mon" | 2 -> "Tue" | 3 -> "Wed"
+ | 4 -> "Thu" | 5 -> "Fri" | 6 -> "Sat" | 7 -> "Sun"
+ | _ -> invalid_arg "short_weekday"
+
+let short_month = function
+ | 1 -> "Jan" | 2 -> "Feb" | 3 -> "Mar" | 4 -> "Apr"
+ | 5 -> "May" | 6 -> "Jun" | 7 -> "Jul" | 8 -> "Aug"
+ | 9 -> "Sep" | 10 -> "Oct" | 11 -> "Nov" | 12 -> "Dec"
+ | _ -> invalid_arg "short_month"