Scala, String representation of a function

Question

is there a way where I can get the string representation of a function?

val f = List(1, 2, 3, 4, 66, 11).foldLeft(55)_

f is a function of type ((Int, Int) => Int) => Int, and that would be the representation I am looking for, but I can't find it anywhere.

the toString method was my first try, of course, but all it returns is <function1>. scala REPL does it right, and the Documentation too. There must be a way?

Regards.

Are you looking for the string representation of a function or the string representation of the type of a function? — Jörg W Mittag, Jan 20 '13 at 15:45
The type, I'd guess. The string must be something like ((Int, Int) => Int) => Int — Danyel, Jan 20 '13 at 15:46
I believe this is how REPL does that: [`TypeStrings`](https://github.com/scala/scala/blob/master/src/compiler/scala/tools/nsc/interpreter/TypeStrings.scala) — Tomasz Nurkiewicz, Jan 20 '13 at 15:53
That's pretty much overkill. sschaef's answer was pretty what I wanted! — Danyel, Jan 20 '13 at 15:59

score 7 · Accepted Answer · edited May 23 '17 at 12:12

7

When the type is known at compile time, you can use Scalas TypeTag:

scala> import reflect.runtime.universe._
import reflect.runtime.universe._

scala> def typeRep[A : TypeTag](a: A) = typeOf[A]
typeRep: [A](a: A)(implicit evidence$1: reflect.runtime.universe.TypeTag[A])reflect.runtime.universe.Type

scala> val f = List(1, 2, 3, 4, 66, 11).foldLeft(55)_
f: ((Int, Int) => Int) => Int = <function1>

scala> typeRep(f)
res2: reflect.runtime.universe.Type = ((Int, Int) => Int) => Int

For a detailed description on what TypeTag is doing see another answer.

edited May 23 '17 at 12:12

Community

1
1

answered Jan 20 '13 at 15:51

kiritsuku

52,967
18
114
136

Okay, this does pretty much what I want, thank you! It seems a little bit "much" though. I guess there isn't an easier way, right? (questions arise like What's TypeTag?) – Danyel Jan 20 '13 at 15:56
2

I gave you a link to another answer on SO, explaining what TypeTag is doing. Reflection is the easiest way to achieve what you want, I think. – kiritsuku Jan 20 '13 at 16:03

Scala, String representation of a function

1 Answers1