如何從 UTCTime 中增加或減少 n 天？

Question

如何從time庫中的UTCTime類型的值中添加/減去 n 天？

Answer 1

import Data.Time

addDaysUtcTime :: UTCTime -> Integer -> UTCTime
addDaysUtcTime t x = addUTCTime (nominalDay * (fromIntegral x)) t

或者

import Data.Time

addDaysUtcTime :: UTCTime -> Integer -> UTCTime
addDaysUtcTime t x = t { utctDay = (addDays x (utctDay t))}