Question

Today I would like to ask what does the => SomeType mean. I found it used in this article. It’s in the part ‘The Sequential Combinator’.

Thanks for any answer!

Answer 1

It means a block of code that you can run.

So for example:

scala> def doTwice(op: =>Unit) = {op; op}
doTwice: (op: => Unit)Unit

scala> doTwice({println("Hi")})
Hi
Hi

In this case the =>Unit is {println("Hi")}

Here “SomeType” is Unit because println doesn’t produce a value. If it produced an Int, it would be =>Int.