Enum Paradise (WORK IN PROGRESS)

Scala enumeration implementation using type macros provided by Macro Paradise

Usage

Enumeration:

object Days extends Enum(Monday, Tuesday, Wednesday, Thursday, Friday)

implicitly[Days.Monday.type <:< Days.Value]

import Days._
def f(x: Value) = x match {
  case Monday => 
  case Tuesday => 
  case Wednesday => 
  case Thursday => 
  //case Friday => 
}
//[warn] /core/src/main/scala/enum.scala:10: match may not be exhaustive.
//[warn] It would fail on the following input: Friday

Enumeration with specific names:

object Months extends Enum(
  January("Jan"),
  February("Feb"),
  Mars("Mar"),
  April("Apr"),
  May,
  June("Jun"),
  July("Jul"),
  August("Aug"),
  September("Sep"),
  October("Oct"),
  November("Nov"),
  December("Dec")
)

def code = Months.values.map(_.name.toUpperCase)

//scala> scalax.MonthsDemo.code
//res1: Seq[String] = List(JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC)

Enumeration with specific value type:

sealed abstract class Planet(val mass: Double, val radius: Double) extends Value

object Planets extends EnumOf[Planet](
  Mercury (3.303e+23, 2.4397e6),
  Venus   (4.869e+24, 6.0518e6),
  Earth   (5.976e+24, 6.37814e6),
  Mars    (6.421e+23, 3.3972e6),
  Jupiter (1.9e+27,   7.1492e7),
  Saturn  (5.688e+26, 6.0268e7),
  Uranus  (8.686e+25, 2.5559e7),
  Neptune (1.024e+26, 2.4746e7)
) {
  def giants = List(Jupiter, Saturn)
}

implicitly[Planets.Value =:= Planet]

//scala> Planets.values.sortBy(_.mass)
//res0: Seq[scalax.Planet] = List(Mercury, Mars, Venus, Earth, Uranus, Neptune, Saturn, Jupiter)

Type Enumeration:

trait Serializable[T] { def serialize(x: T): String }

object Serializable extends TypeEnum[Serializable](
  Int { def serialize(x: Int) = x.toString },
  Double { def serialize(x: Double) = x.toString }
)

def serialize[T : Serializable](x: T) = implicitly[Serializable[T]].serialize(x)

//scala> serialize(42)
//res0: String = 42

//scala> serialize(math.Pi)
//res1: String = 3.141592653589793

License

This software is licensed under the Apache 2 license, quoted below.

Copyright 2009-2012 Alois Cochard 

Licensed under the Apache License, Version 2.0 (the "License"); you may not
use this file except in compliance with the License. You may obtain a copy of
the License at http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations under
the License.