September 2018
Intermediate to advanced
398 pages
9h 43m
English
Content preview from Scala Programming Projects
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Manipulating instances of Option
The following is a simplified definition of the Option ADT:
sealed trait Option[+A]case class Some[A](value: A) extends Option[A]case object None extends Option[Nothing]
The Scala SDK provides a more refined implementation; the preceding definition is just for illustrative purpose. This definition implies that Option can be either of the following two types:
- Some(value), which represents an optional value where the value is present
- None, which represents an optional value where the value is not present.
The + sign in front of the A type parameter in the Option[+A] declaration means that Option is covariant in A. We will explore contravariance in more details in Chapter 4, Advanced Features. For now, you ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.