Read case class object from string in Scala (something like Haskell's “read” typeclass)

Question

I\'d like to read a string as an instance of a case class. For example, if the function were named \"read\" it would let me do the following:

case class Pers         


        

Answer 1

Starting Scala 2.13, it's possible to pattern match a Strings by unapplying a string interpolator:

// case class Person(name: String, age: Int)
"Person(Bob,42)" match { case s"Person($name,$age)" => Person(name, age.toInt) }
// Person("Bob", 42)

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Note that you can also use regexes within the extractor.

Which in this case, helps for instance to match on "Person(Bob, 42)" (age with a leading space) and to force age to be an integer:

val Age = "[ ?*](\\d+)".r

"Person(Bob, 42)" match {
  case s"Person($name,${Age(age)})" => Some(Person(name, age.toInt))
  case _ => None
}
// Person = Some(Person(Bob,42))