CODEWITHSUNDEEP
scala
Eran Medan
Eran Medan

Reputation: 45765

How do I know if a type is a "Number" in runtime (without type classes)

Let's say I don't have the option of using [T: Numeric] type class for some reason.

Is there a way given an "Any" to test if it is a "Number" without using the above?

EDIT: thanks to Lee's comment, it's apparently as easy as in Java: x.isInstanceOf[Number].

My understanding of why it works is: x:Any = 1 is basically in runtime a java.lang.Integer which in turn implements java.lang.Number

Upvotes: 0

Views: 54

Answers (1)

Rahul
Rahul

Reputation: 893

val a = "hello"
val b = 1.34
toNumericOption(a) // None
toNumericOption(b) //Some(1.34)

def toNumericOption(x: Any) = x match {
  case n: java.lang.Number => Some(n)
  case _ => None
}

You can use this to convert to an Option

Upvotes: 5

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