scala-adjectives

Infers adjectives from your case-class nouns. E.g: a (long, interesting) Book

See this blog post for a description of the approach, minus macro code -- this is an older post that I haven't yet gotten around to updating with the macro-based solution you see here.

This macro library infers adjectives from the Noun type parameter. These adjectives can then be used to describe Noun instances as a fluid alternative for constructors.

The adjectives are returned as members of a structural type, an instance of which is created for the supplied noun type. The compiler deals with this correctly, but IntelliJ will complain (yet build and execute your applications nonetheless).

scala-adjectives is implemented using macro paradise 2.10, for quasiquote support. Your client code can be vanilla Scala 2.10. See sample-externaldep/project/Build.scala as an example for setting up an external project dependency on scala-adjectives -- this will cause scala-adjectives to be built by SBT, then used by your project.

Instructions

It is most convenient to add adjectives for a case class as a field called 'adjectives' on its companion object. E.g.:

case class Book(...)
object Book { val adjectives = mkAdjectives[Book] }
import Book.adjectives._
val book = a (long, interesting) Book

Or a more complete example:

import io.github.hunam.adjectives.Adjectives._

sealed abstract class Color
case object red extends Color
case object blue extends Color

object Length extends Enumeration {
  val short, long = Value
}

case class Book(
  coverColor: Color = blue,
  length: Length.Value = Length.short,
  interesting: Boolean = false)

object Book {
  val adjectives = mkAdjectives[Book]
}

// ...

import Book.adjectives._

val book: Book = a (long, interesting) Book

Limitations apply

• only case classes supported for now
• case class properties must be enumerations, booleans, or sealed types. This may be relaxed in the future.
• does not handle ambiguity or duplicate adjectives within scope
• the trailing postfix 'Noun' method is only supported for case classes with default or implicit parameters. You will otherwise be forced to add another apply with the Noun instance, e.g.:

  a (long, interesting) (Book(coverColor = red))