ryanpbrewster

data Genre = Horror | Comedy deriving (Show)
data HorrorAdjective = Scary | Boring deriving (Show)
data ComedyAdjective = Funny | Lame deriving (Show)

data Adjective = HA HorrorAdjective | CA ComedyAdjective deriving (Show)

data Movie = Movie String Genre deriving (Show)

movieDescriptions = [ (Movie "Airplane" Comedy, CA Funny)
                    , (Movie "Jaws" Horror, HA Scary)

ryanpbrewster

class Foo {
  sealed trait A
  case class A1(x: Int) extends A
  case class A2(y: String) extends A
  case class A3(z: Double) extends A

  sealed trait B
  case class B1(z: Int) extends B
  case class B2(z1: Int) extends B

ryanpbrewster

# vecs: an array of real vectors
def crp(vecs):
    clusterVec = []         # tracks sum of vectors in a cluster
    clusterIdx = []         # array of index arrays. e.g. [[1, 3, 5], [2, 4, 6]]
    ncluster = 0
    # probablity to create a new table if new customer
    # is not strongly "similar" to any existing table
    pnew = 1.0/ (1 + ncluster)  
    N = len(vecs)
    rands = random.rand(N)         # N rand variables sampled from U(0, 1)

ryanpbrewster

case class Person(
  id: Option[Long] = None,
  firstName: String,
  lastName: String,
  birthDate: LocalDate)

ryanpbrewster

import play.api.libs.json._
implicit val personFormat = Json.format[Person]
Json.toJson(Person(Some(1), "Arthur", "Dent", "[email protected]", new LocalDate("1952-03-11")))
// => {"id":1,"firstName":"Arthur","lastName":"Dent",birthDate":"1952-03-11"}

ryanpbrewster

case class Id[T](id: Long) {  // in Id library
  override def toString = id.toString
}
case class Name(firstName: String, lastName: String) { 
  def firstLast = s"$firstName $lastName"
  def lastFirst = s"$lastName, $firstName"
}
case class Person(
  id: Option[Id[Person]] = None,
  name: Name,

ryanpbrewster

def idFormat[T]: Format[Id[T]] = Format(
  __.read[Long].map(Id(_)),
  new Writes[Id[T]]{ def writes(o: Id[T]) = JsNumber(o.id) }
)
implicit val personIdFormat = idFormat[Person]
implicit val nameFormat = Json.format[Name]
implicit val personFormat = Json.format[Person]
Json.toJson(Person(Some(Id(1)), Name("Arthur","Dent"), "[email protected]", new LocalDate("1952-03-11")))
// => {"id":1,"name":{"firstName":"Arthur","lastName":"Dent"},"email":"[email protected]","birthDate":"1952-03-11"}

ryanpbrewster

import play.api.libs.functional.syntax._
implicit val personFormat: Format[Person] = (
  (__ "id").formatNullable[Id[Person]] and
  (
    (__ "firstName").format[String] and 
    (__ "lastName").format[String]
  )(Name.apply, unlift(Name.unapply)) and
  (__ "email").format(Reads.email) and
  (__ "birthDate").format[LocalDate]
)(Person.apply, unlift(Person.unapply))

ryanpbrewster

val personFormatOld: Format[Person] = ??? // old serializer
val personFormat: Format[Person] = ??? // new serializer
implicit val personReads: Reads[Person] = personFormat orElse personFormatOld
implicit val personWrites: Writes[Person] = personFormat

ryanpbrewster

implicit val personFormat: Format[Person] = (
  (__ "id").formatNullable[Id[Person]] and
  (__ "name").format[Name] and
  (__ "email").formatNullable(
    Format(Reads.email, Writes.StringWrites))
      .inmap[String](_.getOrElse(""), Some(_).filterNot(_.isEmpty)
    ) and
  (__ "birthDate").format[LocalDate]
)(Person.apply, unlift(Person.unapply)) 
Json.fromJson[Person](Json.parse("""{