September 2018
Intermediate to advanced
398 pages
9h 43m
English
Content preview from Scala Programming Projects
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Laws
The documentation mentions a very important point: the instances of the type class must implement an associative combine function.
This means that they must verify the following law:
a combine (b combine c) = (a combine b) combine c
Most type classes in Cats have their own specific laws. The library guarantees that the type class instances that it defines verify this law. However, if you implement your own instance of a type class, it is your responsibility to verify that it does not break any law.
A user of a type class instance expects that it verifies all of the laws of the type class; it is part of the type class’s contract.
A type class contract is the type class trait plus the laws.
When a type class verifies certain laws, 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.