Scala example source code file (GenerateTupleW.scala)

This example Scala source code file (GenerateTupleW.scala) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Scala by Example" ^TM.

Learn more about this Scala project at its project page.

Java - Scala tags/keywords

anyval, file, generatetuplew, indexedseq, int, ops, string, totuple, totupleops, tuple

The GenerateTupleW.scala Scala example source code

import sbt._

object GenerateTupleW {

  def apply(outputDir: File) = {
    val arities = 2 to 12

    def writeFileScalazPackage(fileName: String, source: String): File = {
      val file = (outputDir / "scalaz" / "syntax" / "std" / fileName).asFile
      IO.write(file, source)
      file
    }

    def double(s: String) = s + s

    val tuples: IndexedSeq[(String, String)] = for (arity: Int <- arities) yield {
      case class N(n: Int) {
        val alpha: String = ('A' + (n - 1)).toChar.toString
        val alpha2: String = alpha + alpha
        val element: String = "_" + n
      }
      val ns = (1 to arity) map N.apply
      def mapMkString(f: N => String): String = ns.map(f).mkString(", ")

      val tparams = mapMkString {
        n => n.alpha
      }
      val params = mapMkString {
        n => n.element
      }

      val ztparams = mapMkString {
        _ => "Z"
      }

      val mapallTParams = mapMkString {
        n => n.alpha2
      }
      val mapallParams = mapMkString {
        n => s"${n.element}: (${n.alpha} => ${n.alpha2}) = identity[${n.alpha}] _"
      }
      val mapallApply = mapMkString {
        n => s"${n.element}(value.${n.element})"
      }

      val pimp = s"""|
          |final class Tuple${arity}Ops[${tparams}](val value: (${tparams})) extends AnyVal {
          |  def fold[Z](f: => (${tparams}) => Z): Z = {import value._; f(${params})}
          |  def toIndexedSeq[Z](implicit ev: value.type <:< Tuple${arity}[${ztparams}]): IndexedSeq[Z] = {val zs = ev(value); import zs._; IndexedSeq(${params})}
          |  def mapElements[${mapallTParams}](${mapallParams}): (${mapallTParams}) = (${mapallApply})
          |}""".stripMargin

      val conv = s"""implicit def ToTuple${arity}Ops[${tparams}](t: (${tparams})): Tuple${arity}Ops[${tparams}] = new Tuple${arity}Ops(t)\n"""
      (pimp, conv)
    }

    val source = "package scalaz\npackage syntax\npackage std\n\nimport collection.immutable.IndexedSeq\n\n" +
      tuples.map(_._1).mkString("\n") +
      "\n\ntrait ToTupleOps {\n" +
         tuples.map("  " + _._2).mkString("\n") +
      "}"
    writeFileScalazPackage("TupleOps.scala", source)
  }

}