Examples of using Booleans to filter optional values.

BooleanOptions.scala

// Example values.
val applyTitle = true
val title = Some("This is my Title!")

// We want to map these values to Option[Option[String]]
// where Option[String] is our value, and the outer Option[_]
// is an indicator on wether we should later use the value or not.
//
// eg: We want to support three use-cases:
//
//   * The value should be applied:       Some(Some("This is my Title!"))
//   * The value should be cleared:       Some(None)
//   * The value should not be modified:  None

// Some examples below are condensed to one line where it seemed
// idiomatically appropriate (eg: how I would write it in actual code).

// BEGIN EXAMPLE 1
val example1 = applyTitle match {
  case true => Some(title)
  case false => None
}

// BEGIN EXAMPLE 2
val example2 = if(applyTitle) Some(title) else None

// You could inject newlines, but I feel like the indentation
// would feel more awkward than just condensing it to one line.

// BEGIN EXAMPLE 3
val example3 = Option(applyTitle) filter(identity) map(_ => title)

// Newlines would require leading .dot notation on the method calls, and
// I feel like the above reads better.

// BEGIN EXAMPLE 4	
val example4 = Option(applyTitle) collect { case true => title }

// Of the one-liner functional examples I like this one is best.
// It also helps to flex a method that I feel like could be used more
// frequently if I trained myself better.

// BEGIN EXAMPLE 5
implicit class BooleanOption(value: Boolean) {
  def collect[T](substitution: T): Option[T] = {
    if(value)
      Some(substitution)
    else
      None
  }
}

val example5 = applyTitle collect title

// If I needed to perform this operation a dozen or more times this
// is the version I'd go with. Drop the implicit into a util package object
// and reuse whenever I feel like it.
//
// I called the method "map" at first, but I feel like "collect" actually
// reinforces the type signatures better. ie: If I "collect" a "true" value
// Some(substitution) is a reasonable expectation.