A pattern of converting a one-track-input Function to a two-track-input Function for better function-composition-ability in the presence of Option types. Inspired by Maybe Monad.

BindOption.scala

// Convert a One-Track-Input Function to Two-Track-Input Function for better
// Composability of Function in the presence of Option types

def bindOption[A, B](f: A => Option[B]): Option[A] => Option[B] = {
  (input) => input match {
    case Some(a) => f(a)
    case None    => None
  }
}

def otherBindOption[A, B](f: A => B, default: B): Option[A] => B = {
  (input) => input match {
    case Some(a) => f(a)
    case None    => default
  }
}

def stringToOptionInt(s: String): Option[Int] = Some(s.toInt)

def stringToInt(s: String): Int = s.toInt

// Testing Them

val twoTrackFunction = bindOption(stringToOptionInt)
val otherTwoTrackFunction = otherBindOption(stringToInt, 10)

val str = Some("123")
val str2: Option[String] = None

val result = twoTrackFunction(str)
val result2 = otherTwoTrackFunction(None)

println(result)   // #=> Some(123)
println(result2)  // #=> 10