Scala example source code file (String.scala)

This example Scala source code file (String.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

boolean, double, float, isempty, long, nonemptylist, numberformatexception, short, string, stringfunctions, stringinstances, validation

The String.scala Scala example source code

package scalaz
package std

trait StringInstances {
  implicit object stringInstance extends Monoid[String] with Show[String] with Equal[String] with Order[String] with IsEmpty[λ[α => String]] {
    type SA[α] = String
    def append(f1: String, f2: => String) = f1 + f2
    def zero: String = ""
    override def show(f: String) = '"' + f + '"'
    def order(x: String, y: String) = Ordering.fromInt(x.compareTo(y))
    override def equal(x: String, y: String) = x == y
    override def equalIsNatural: Boolean = true
    def empty[A] = zero
    def plus[A](f1: SA[A], f2: => SA[A]) = f1 + f2
    def isEmpty[A](s: SA[A]) = s == ""
  }
}

trait StringFunctions {
  /**
   * Returns the same String value if the given value is 1 otherwise pluralises this String by appending an "s" unless
   * this String ends with "y" and not one of ["ay", "ey", "iy", "oy", "uy"] in which case the 'y' character is chopped and "ies"
   * is appended.
   */
  def plural(s:String, n: Long): String = if(n == 1L) s else
  if((s endsWith "y") && (List("ay", "ey","iy", "oy", "uy") forall (!s.endsWith(_)))) s.take(s.length - 1) + "ies"
  else s + "s"

  /**
   * Constructs a non-empty list with the value if it is not empty, otherwise, throws an error.
   */
  def charsNel(s:String) : Option[NonEmptyList[Char]] = list.toNel(s.toList)

  /**
   * Constructs a non-empty list with the given string if it is not empty, otherwise, returns the second argument.
   */
  def charsNel(s:String, e: => NonEmptyList[Char]) : NonEmptyList[Char] = charsNel(s) getOrElse e

  // Parsing functions.

  def parseBoolean(s:String): Validation[IllegalArgumentException, Boolean] =
    Validation.fromTryCatchThrowable[Boolean, IllegalArgumentException](s.toBoolean)

  def parseByte(s:String): Validation[NumberFormatException, Byte] =
    Validation.fromTryCatchThrowable[Byte, NumberFormatException](s.toByte)

  def parseShort(s:String): Validation[NumberFormatException, Short] =
    Validation.fromTryCatchThrowable[Short, NumberFormatException](s.toShort)

  def parseInt(s:String): Validation[NumberFormatException, Int] =
    Validation.fromTryCatchThrowable[Int, NumberFormatException](s.toInt)

  def parseLong(s:String): Validation[NumberFormatException, Long] =
    Validation.fromTryCatchThrowable[Long, NumberFormatException](s.toLong)

  def parseFloat(s:String): Validation[NumberFormatException, Float] =
    Validation.fromTryCatchThrowable[Float, NumberFormatException](s.toFloat)

  def parseDouble(s:String): Validation[NumberFormatException, Double] =
    Validation.fromTryCatchThrowable[Double, NumberFormatException](s.toDouble)

  def parseBigInt(s:String): Validation[NumberFormatException, BigInt] =
    Validation.fromTryCatchThrowable[BigInt, NumberFormatException](BigInt(s))

  def parseBigDecimal(s:String): Validation[NumberFormatException, BigDecimal] =
    Validation.fromTryCatchThrowable[BigDecimal, NumberFormatException](BigDecimal(s))
}

object string extends StringInstances with StringFunctions {
  object stringSyntax extends scalaz.syntax.std.ToStringOps
}