How scala handle nested parametrization?

Question

Consider an example:

public def someFunc(f: (One Pair Two Pair Three) => Future[Two]) : SomeResultType = {...}

case class One(...)
case class Two(...)
case class Three(...)

Pair is scala.Predef#Pair What does scala.Predef#Pair mean? As I know I can write function calls in scala like this println "string" but in that case token are types. What does the actual type of expression One Pair Two Pair Three?

senia · Accepted Answer · 2015-02-09 08:19:00Z

3

You could use REPL to get your answer:

scala> def ttt: Int Pair Long Pair String = ???
ttt: Pair[Pair[Int,Long],String]

Type A B C means B[A, C] in scala.

So One Pair Two Pair Three means Pair[One,Two] Pair Three means Pair[Pair[One, Two], Three].

Pair is just a type alias to Tuple2.

Note that Pair is deprecated, you should use Tuple2 instead: ((One, Two), Three).

edited Feb 9, 2015 at 8:19

answered Feb 9, 2015 at 7:07

senia

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