Scala Stream Contiually get rid of var-CodePudding

I'm trying to generate an infinite list of dates by substracting one month from the current date, i want to do this using Streams.

Here's what i've done so far :

import org.joda.time.LocalDate

var date = new LocalDate("2022-05-24")
val dateSeq = Seq(date)
val allDates = dateSeq.toStream    Stream.continually(dateSeq)
  .flatMap(ticks => ticks.map(_ => {
    date = date.minusMonths(1)
    date
  }))
allDates.take(5).toList

My problem is that im using a var to decrement the current date by a month each time.

Is there any way to get rid of that var ?

CodePudding user response：

Using @Luis Miguel Mejía Suárez solution:

import org.joda.time.LocalDate

val numberOfMonthsBack = 5
val date = new LocalDate("2022-05-24")
val dateSeq = Seq(date)
val allDates = dateSeq.toStream    Stream.continually(dateSeq)
  .zip(Stream.from(1))
  .flatMap(ticks => 
    ticks._1.map(x => x.minusMonths(ticks._2))
  )
allDates
  .take(numberOfMonthsBack).toList

CodePudding user response：

You just want .iterate rather than .continually:

    vall allDates = Stream.iterate(LocalDate.now) { _.minusMonth(1) }