October 2014
Intermediate to advanced
280 pages
7h 20m
English
Content preview from Programming Elixir
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Pattern Matching and Updating Maps
The question we most often ask of our maps is, “Do you have the following keys (and maybe values)?”
-
Is there an entry with the key :name?
-
Are there entries for the keys :name and :height?
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Does the entry with key :name have the value "Dave"?
Here’s how we ask these questions using Elixir patterns.
| | iex> person = %{ name: "Dave", height: 1.88 } |
| | %{height: 1.88, name: "Dave"} |
| | iex> %{ name: a_name } = person |
| | %{height: 1.88, name: "Dave"} |
| | iex> a_name |
| | "Dave" |
| | iex> %{ name: _, height: _ } = person |
| | %{height: 1.88, name: "Dave"} |
| | iex> %{ name: "Dave" } = person |
| | %{height: 1.88, name: "Dave"} |
Our map does not have the key :weight, so the following pattern match fails:
| | iex> %{ ... |
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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.