How to use a typed Scala Trait in generic function?

Question

scala> trait BaseTrait[T] { def foo(e: T): String}
defined trait BaseTrait

scala> class C1 extends BaseTrait[String] {def foo(e: String) = "C1"}
defined class C1

scala> class C2 extends BaseTrait[Int] {def foo(e: Int) = e.toString}
defined class C2

scala> def general(e :BaseTrait) = {println(e.foo())}
<console>:43: error: trait BaseTrait takes type parameters
`enter code here`def general(e :BaseTrait) = {println(e.foo())}

That defeats polymorphic behavior...how do I define generic functions that consume BaseTrait?

def general(e :BaseTrait[_]) but this is still not going to work. e.foo takes parameters. Check parametric polymorphism, it seems you want ad hoc polymorphism. — pedrofurla
– pedrofurla, Commented Apr 28, 2017 at 20:38
@user7938511 You conveniently didn't specify where you were going to get a valid argument to pass to foo without parametrizing. — Jasper-M
– Jasper-M, Commented Apr 28, 2017 at 20:42

Jasper-M · Accepted Answer · 2017-04-28 20:45:26Z

1

One valid definition of general would be

def general[A](e: BaseTrait[A], a: A) = println(e.foo(a))

answered Apr 28, 2017 at 20:45

Jasper-M

15.2k2 gold badges28 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to use a typed Scala Trait in generic function?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related