Minitime @pishen + - × ÷ 

please! give me a star 

Datetime libraries for Java Joda Time Java Time since Java 8 Minitime 

ZonedDateTime Basic Components in Java Time LocalDate LocalDateTime LocalTime 2019-08-11T15:19:27.289+08:00 

Date Operations in Java Time LocalDate.of(2019,8,31).plusMonths(3) LocalDate.of(2019,8,31).plusWeeks(2) LocalDate.of(2019,8,31).plusYears(1) LocalDate.of(2019,8,31).plus(Period.ofMonths(2).plusDays(3)) LocalDate.of(2019,8,31).plusDays(4) 

LocalDate(2019,8,31) + 4.days LocalDate(2019,8,31) + 3.months LocalDate(2019,8,31) + 2.weeks LocalDate(2019,8,31) + 1.year LocalDate(2019,8,31) + (2.months + 3.days) Date Operations in Minitime 

Arithmetic Rules in Minitime LocalDate Period + = LocalDate LocalDate Period - = LocalDate Period Period + = Period Period Period - = Period LocalDate LocalDate - = Period Period Int * = Period 

Arithmetic Rules in Minitime LocalTime Duration + = LocalTime LocalDateTime Period - = LocalDateTime ZonedDateTime Duration + = ZonedDateTime Duration Duration + = Duration LocalDateTime LocalDateTime - = Duration Duration Int * = Duration Duration Int / = Duration LocalTime LocalTime - = Duration ZonedDateTime Period - = ZonedDateTime and more... 

Date Comparison in Java Time LocalDate.of(2019,8,13).isAfter(LocalDate.of(2019,8,12)) LocalDate.of(2019,8,13).isBefore(LocalDate.of(2019,8,14)) !LocalDate.of(2019,8,13).isBefore(LocalDate.of(2019,8,13)) !LocalDate.of(2019,8,13).isAfter(LocalDate.of(2019,8,13)) 

Date Comparison in Minitime LocalDate(2019,8,13) > LocalDate(2019,8,12) LocalDate(2019,8,13) < LocalDate(2019,8,14) LocalDate(2019,8,13) >= LocalDate(2019,8,13) LocalDate(2019,8,13) <= LocalDate(2019,8,13) 

Date Ordering in Java Time Seq(date1, date2, date3).sorted Seq(date1, date2, date3).max Seq(date1, date2, date3).min ✘ ✘ ✘ 

Date Ordering in Minitime (Fixed in Scala 2.13) ✔ ✔ ✔ Seq(date1, date2, date3).sorted Seq(date1, date2, date3).max Seq(date1, date2, date3).min import minitime._ 

Ordered vs. Ordering Comparable Comparator Java Scala Ordered Ordering 

scala.math.Ordering[T] trait Seq[A] { def sorted(implicit ord: Ordering[A]): Seq[A] } Seq(5,4,3,2,1).sorted implicit val intOrd: Ordering[Int] = ... (intOrd) (Included in Scala Standard Library) 

scala.math.Ordering[T] Seq(date1,date2,date3).sorted( ) ? implicit val dateOrd: Ordering[LocalDate] = ??? 

scala.math.Ordering[T] trait Ordering[T] { def compare(x: T, y: T): Int } implicit val dateOrd = new Ordering[LocalDate] { } Seq(date1,date2,date3).sorted (Included in Minitime) Typeclass override def compare(x: LocalDate, y: LocalDate) = { x.compareTo(y) } (dateOrd) 

minitime.Add[L, R] trait Add[L, R] { def apply(l: L, r: R): L } val add = new Add[LocalDate,Period] { override def apply(l: LocalDate, r: Period) = { l.plus(r) } } add.apply(LocalDate(2019,8,17), 3.days) // LocalDate(2019,8,20) 

minitime.Add[L, R] trait Add[L, R] { def apply(l: L, r: R): L } val add = new Add[LocalDate,Period] { override def apply(l: LocalDate, r: Period) = { l.plus(r) } } add(LocalDate(2019,8,17), 3.days) // LocalDate(2019,8,20) 這啥？要幹嘛？ 

Implicit Classes LocalDate(2019,8,17) + 3.days implicit class Infix(l: LocalDate) { def +(r: Period) = l.plus(r) } 

Implicit Classes new Infix(LocalDate(2019,8,17)) + 3.days implicit class Infix(l: LocalDate) { def +(r: Period) = l.plus(r) } 

Implicit Classes implicit class Infix(l: LocalDateTime) { } LocalDateTime.now + 3.days LocalDateTime.now + 3.minutes def +(r: Period) = l.plus(r) def +(r: Duration) = l.plus(r) 

Polymorphism? implicit class Infix(l: Temporal) { def +(r: TemporalAmount) = l.plus(r) } TemporalAmount Temporal Period Duration LocalDate LocalDateTime joda.time.LocalDate joda.time.Period ✘ ✘ 

Type Parameter implicit class Infix[L](l: L) { def +[R](r: R) = } ??? 

minitime.Add[L, R] implicit class Infix[L](l: L) { def +[R](r: R)(implicit add: Add[L,R]) = } ??? 

minitime.Add[L, R] implicit class Infix[L](l: L) { def +[R](r: R)(implicit add: Add[L,R]) = add(l,r) } implicit val ldp: Add[LocalDate,Period] = ... implicit val jda: Add[joda.time.LocalDate,Period] = ... LocalDate(2019,8,17) + 3.days new joda.time.LocalDate(2019,8,17) + 3.days 

One Implicit Class to Rule Them All implicit class Infix[L](l: L) { def +[R](r: R)(implicit add: Add[L,R]) = add(l,r) } 

One Implicit Class to Rule Them All implicit class Infix[L](l: L) { def +[R](r: R)(implicit add: Add[L,R]) = add(l,r) def -[R,C](r: R)(implicit sub: Subtract[L,R,C]) = sub(l,r) } 

One Implicit Class to Rule Them All implicit class Infix[L](l: L) { def +[R](r: R)(implicit add: Add[L,R]) = add(l,r) def -[R,C](r: R)(implicit sub: Subtract[L,R,C]) = sub(l,r) def *(s: Int)(implicit mul: Multiply[L]) = mul(l,s) } 

One Implicit Class to Rule Them All implicit class Infix[L](l: L) { def +[R](r: R)(implicit add: Add[L,R]) = add(l,r) def -[R,C](r: R)(implicit sub: Subtract[L,R,C]) = sub(l,r) def *(s: Int)(implicit mul: Multiply[L]) = mul(l,s) def /[R,C](r: R)(implicit div: Divide[L,R,C]) = div(l,r) } 

Arithmetic Rules in Minitime LocalTime Duration + = LocalTime LocalDateTime Period - = LocalDateTime ZonedDateTime Duration + = ZonedDateTime Duration Duration + = Duration LocalDateTime LocalDateTime - = Duration Duration Int * = Duration Duration Int / = Duration LocalTime LocalTime - = Duration ZonedDateTime Period - = ZonedDateTime 

Arithmetic Rules in Minitime implicit val a1: Add[LocalTime,Duration] LocalDateTime Period - = LocalDateTime ZonedDateTime Duration + = ZonedDateTime Duration Duration + = Duration LocalDateTime LocalDateTime - = Duration Duration Int * = Duration Duration Int / = Duration LocalTime LocalTime - = Duration ZonedDateTime Period - = ZonedDateTime 

Arithmetic Rules in Minitime implicit val a1: Add[LocalTime,Duration] ZonedDateTime Duration + = ZonedDateTime Duration Duration + = Duration LocalDateTime LocalDateTime - = Duration Duration Int * = Duration Duration Int / = Duration LocalTime LocalTime - = Duration ZonedDateTime Period - = ZonedDateTime implicit val s1: Subtract[LocalDateTime,Period,LocalDateTime] 

Arithmetic Rules in Minitime And everyone can add his own rules... implicit val a2: Add[ZonedDateTime,Duration] implicit val a3: Add[Duration,Duration] implicit val s2: Subtract[LocalDateTime,LocalDateTime,Duration implicit val m1: Multiply[Duration] implicit val d1: Divide[Duration,Int,Duration] implicit val s3: Subtract[LocalTime,LocalTime,Duration] implicit val s4: Subtract[ZonedDateTime,Period,ZonedDateTime] implicit val s1: Subtract[LocalDateTime,Period,LocalDateTime] implicit val a1: Add[LocalTime,Duration] 

Reusing Typeclasses Add[L,R] Subtract[L,R,C] Multiply[L] Divide[L,R,C] Infix[L] TimeRange[T,S] Ordering[T] 

minitime.TimeRange[T, S] // TimeRange( // 2019-08-23,2019-08-24,2019-08-25,2019-08-26,2019-08-27 // ) val dates: TimeRange[LocalDate,Period] = { } LocalDate(2019,8,23) to LocalDate(2019,8,27) 

minitime.TimeRange[T, S] // TimeRange( // 2019-08-23,2019-08-25,2019-08-27 // ) val dates: TimeRange[LocalDate,Period] = { } LocalDate(2019,8,23) to LocalDate(2019,8,27) by 2.days 

minitime.TimeRange[T, S] val dates: TimeRange[LocalDate,Period] = { } LocalDate(2019,8,23) to LocalDate(2019,8,27) by 2.days val dateSeq: Seq[LocalDate] = dates // Seq( // 2019-08-23,2019-08-25,2019-08-27 // ) 

Question 1 在明年的聖誕節之前，還有幾個13號星期五？ val dates = (LocalDate.now to LocalDate(2020,12,25)) .filter(d => d.getDayOfWeek == FRIDAY && d.getDayOfMonth == 13) // Seq(2019-09-13, 2019-12-13, 2020-03-13, 2020-11-13) 

Question 2 承上題，每個13號星期五彼此之間相隔幾天？ 2019-09-13 2019-12-13 2020-03-13 2020-11-13 ? days ? days ? days 

Question 2 承上題，每個13號星期五彼此之間相隔幾天？ dates.zip(dates.tail).map { case (a, b) => b - a } // Seq(P91D, P91D, P245D) 2019-09-13 2019-12-13 2020-03-13 2020-11-13 91 days 91 days 245 days 

Question 3 承上上題，有幾個13號星期五會出現在 下一個母親節 跟 下一個感恩節 之間？ (五月的第二個星期日 ) (11月的第四個星期四) val mother = (LocalDate(2020,5,1) to LocalDate(2020,5,31)) .filter(_.getDayOfWeek == SUNDAY)(1) val turkey = (LocalDate(2019,11,1) to LocalDate(2019,11,30)) .filter(_.getDayOfWeek == THURSDAY)(3) dates.filter(d => d > turkey && d < mother) // Seq(2019-12-13, 2020-03-13) 

Cross Compile to JavaScript Minitime using Scala.js 

Give it a Try Issues and PRs are welcomed. 

Than[K] Yo[U]