Time types and how to construct them

Time

Time is exported from purescript-datetime

data Time = Hour Minute Second Millisecond

We can use the Time constructor, but there’s no way to directy build a value for Hour, Minute, Second and Millisecond.

What we can do is use (<$>) and [(<>)](https://pursuit.purescript.org/packages/purescript-prelude/4.1.1/docs/Control.Apply#v:(%3C%3E)) to build a Maybe value (or lift4 the constructor):

myTime :: Maybe Time
myTime = Time <$> toEnum 20 <*> toEnum 30 <*> toEnum 0 <*> toEnum 0 -- ^ 20:30:00

-- Can also be written as:
myTime :: Maybe Time
myTime = lift4 Time (toEnum 20) (toEnum 30) (toEnum 0) (toEnum 0)

-- Or by using Maybe's monad instance:
myTime :: Maybe Time
myTime = do
  h <- toEnum 20
  m <- toEnum 30
  s <- toEnum 0
  ms <- toEnum 0
  pure $ Time h m s ms

Hour

Hour is exported from purescript-datetime and is in the 24-hours format.

newtype Hour = Hour Int

The Hour constructor is not exported, so we have to use toEnum to build it.

myHour :: Maybe Hour
myHour = toEnum 22 -- ^ Values go from 0 to 23

Minute

Minute is exported from purescript-datetime.

newtype Minute = Minute Int

The Minute constructor is not exported, so we have to use toEnum to build it.

myMinutes :: Maybe Minute
myMinutes = toEnum 22 -- ^ Values go from 0 to 59

Second

Second is exported from purescript-datetime.

The Second constructor is not exported, so we have to use toEnum to build it.

mySeconds :: Maybe Second
mySeconds = toEnum 22 -- ^ Values go from 0 to 59

Millisecond

Millisecond is exported from purescript-datetime.

The Millisecond constructor is not exported, so we have to use toEnum to build it.

myMilliseconds :: Maybe Millisecond
myMilliseconds = toEnum 300 -- ^ Values go from 0 to 999