Iterate over dates range (the scala way)

Question

Given a start and an end date I would like to iterate on it by day using a foreach, map or similar function. Something like

(DateTime.now to DateTime.now + 5.day         


        

Answer 1

In this case, the Scala way is the Java way:

When running Scala on Java 9+, we can use java.time.LocalDate::datesUntil:

import java.time.LocalDate
import collection.JavaConverters._

// val start = LocalDate.of(2019, 1, 29)
// val end   = LocalDate.of(2018, 2,  2)
start.datesUntil(end).iterator.asScala
// Iterator[java.time.LocalDate] =  (2019-01-29, 2019-01-30, 2019-01-31, 2019-02-01)

And if the last date is to be included:

start.datesUntil(end.plusDays(1)).iterator.asScala
// 2019-01-29, 2019-01-30, 2019-01-31, 2019-02-01, 2019-02-02