scala repl setting and logs

Question

My scala repl is not showing the logs on the screen as some books and forums seem to suggest. I am on scala 2.12.1. My scala repl when I try below syntax

scala> def sum(a:Int, b:Int) = a+ b
sum: (a: Int, b: Int)Int

Should show as below

scala> val fun2 = sum _
fun2: (Int, Int) => Int = <function2>

But it is showing as below:

scala> val fun2 = sum _
fun2: (Int, Int) => Int = $$Lambda$1623/2005055216@13bdf19

It is not showing the trait like <function2> etc. How do I fix this?

Yuval Itzchakov · Answer 1 · 2017-04-23T07:22:51.667

0

I am assuming this is due to the way Scala 2.12 now SAM converts Scala functions SAM interfaces. If you want to see the type of an expression, prepend :t to the declaration:

scala> :t val fun2 = sum _
(Int, Int) => Int

edited Apr 23 '17 at 07:22

answered Apr 23 '17 at 07:19

Yuval Itzchakov

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but it is not showing the things like and all still. Can you tell why and how to fix that? – curiousengineer Apr 23 '17 at 07:21
`(Int, Int) => Int` is syntax sugar for `Function2[Int, Int, Int]`. I am not sure there is a way to roll back to previous presentation. – Yuval Itzchakov Apr 23 '17 at 07:22

score 0 · Answer 2 · answered Jan 04 '18 at 09:17

The Scala 2.12 type checker accepts a function literal as a valid expression for any Single Abstract Method (SAM) type, in addition to the FunctionN types from standard library. This improves the experience of using libraries written for Java 8 in Scala.

scala> val runRunnable: Runnable = () => println("Run!")

runRunnable: Runnable = $$Lambda$1073/754978432@7cf283e1

scala> runRunnable.run() Run!

scala repl setting and logs

2 Answers2