CODEWITHSUNDEEP
scalaimplicit-conversionimplicit
Vinit Sacheti
Vinit Sacheti

Reputation: 23

implicit conversion for a list of tuple

I am trying to convert implicitly a List[(Int, String)] to List[(IntWrap, String)], which is giving an error of TypeMismatch.

I tried few other conversion which works which are List[Int] to List[IntWrap] and Tuple2[Int, String] to Tuple2[IntWrap, String] which works.

case class IntWrap(a : Int)

implicit def int2IntWrap(x: Int) = IntWrap(x)

implicit def int2IntWrapForTuple2(tuple: Tuple2[Int, String])  = (IntWrap(tuple._1), tuple._2)

//Defined few methods
def foo(t : (IntWrap, String)) = println(t._2)

def foo_list(t: List[IntWrap]) = println(t.size)

def foo_list_tuple(t : List[(IntWrap, String)]) = println(t.size)

foo(3 -> "hello") //this works

foo_list(List(1, 2, 3)) //this works

val l :  List[(IntWrap, String)] = List(3 -> "hello")

foo_list_tuple(l) //this works

val l1 = List(3 -> "hello")
foo_list_tuple(l1) //this one doesn't work
//error: type mismatch; found: List[(Int, String)] required: List[(IntWrap, String)]

How can I make this work?

Upvotes: 0

Views: 376

Answers (1)

Mario Galic
Mario Galic

Reputation: 48410

Try defining implicit conversion like so

implicit def listOfTupleToListOfIntWrapTuple(l: List[(Int, String)]): List[(IntWrap, String)] =
  l.map(tuple => (IntWrap(tuple._1), tuple._2))

Upvotes: 1

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