Kotlin calendar DSL

CalendarDsl.kt

import java.util.*

@DslMarker
annotation class CalendarDsl

@CalendarDsl
class CalendarBuilder(val calendar: Calendar) {
    fun dayOfMonth(function: () -> Int) = calendar.apply { set(Calendar.DAY_OF_MONTH, function()) }

    fun dayOfMonth(value: Int) = calendar.apply { set(Calendar.DAY_OF_MONTH, value) }

    fun month(function: () -> Int) = calendar.apply { set(Calendar.MONTH, function()) }

    fun month(value: Int) = calendar.apply { set(Calendar.MONTH, value) }

    fun year(function: () -> Int) = calendar.apply { set(Calendar.YEAR, function()) }

    fun year(value: Int) = calendar.apply { set(Calendar.YEAR, value) }

    fun hourOfDay(function: () -> Int) = calendar.apply { set(Calendar.HOUR_OF_DAY, function()) }

    fun hourOfDay(value: Int) = calendar.apply { set(Calendar.HOUR_OF_DAY, value) }

    fun minute(function: () -> Int) = calendar.apply { set(Calendar.MINUTE, function()) }

    fun minute(value: Int) = calendar.apply { set(Calendar.MINUTE, value) }

    fun date(dayOfMonth: Int, month: Int, year: Int) = calendar.apply {
        set(Calendar.DAY_OF_MONTH, dayOfMonth)
        set(Calendar.MONTH, month)
        set(Calendar.YEAR, year)
    }

    fun time(hourOfDay: Int, minute: Int) = calendar.apply {
        set(Calendar.HOUR_OF_DAY, hourOfDay)
        set(Calendar.MINUTE, minute)
    }
}

@CalendarDsl
fun kalendar(setup: CalendarBuilder.() -> Unit): Calendar = with(CalendarBuilder(Calendar.getInstance())) {
    setup()
    calendar
}

@CalendarDsl
fun Calendar.dsl(setup: CalendarBuilder.() -> Unit): Calendar = with(CalendarBuilder(this)) {
    setup()
    calendar
}

Example1.kt

private fun generateFakeCalendar() = kalendar {
  dayOfMonth { 12 }
  month { 3 }
  year { 2019 }
  hourOfDay { 9 }
  minute { 27 }
}

Example2.kt

private fun generateFakeCalendar() = kalendar {
  dayOfMonth(12)
  month(3)
  year(2019)
  hourOfDay(9)
  minute(27)
}

Example3.kt

private fun generateFakeCalendar() = kalendar {
  date(12, 3, 2019)
  time(9, 27)
}

Example4.kt

private fun generateFakeCalendar() = Calendar.getInstance().dsl {
  dayOfMonth(12)
  month(3)
  year(2019)
  hourOfDay(9)
  minute(27)
}