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Clojure Programming Cookbook

You're reading from   Clojure Programming Cookbook Handle every problem you come across in the world of Clojure programming with this expert collection of recipes

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Product type Paperback
Published in Oct 2016
Publisher Packt
ISBN-13 9781785885037
Length 618 pages
Edition 1st Edition
Languages
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Authors (2):
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Nicolas Modrzyk Nicolas Modrzyk
Author Profile Icon Nicolas Modrzyk
Nicolas Modrzyk
Makoto Hashimoto Makoto Hashimoto
Author Profile Icon Makoto Hashimoto
Makoto Hashimoto
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Toc

Table of Contents (11) Chapters Close

Preface 1. Live Programming with Clojure FREE CHAPTER 2. Interacting with Collections 3. Clojure Next 4. File Access and the Network 5. Working with Other Languages 6. Concurrency and Parallelism 7. Advanced Tips 8. Web Applications 9. Testing 10. Deployment and DevOps

Merging and splitting collections

Sometimes, you'd like to merge multiple collections into a single collection or split a single collection into multiple collections. Let's have a look these cases.

Getting ready

You only need REPL, described in the Repl up! recipe in Chapter 1, Live Programming with Clojure, and no additional libraries. Start REPL, and you can review the sample code in this recipe.

How to do it...

Let's see how to merge and split collections.

Using merge and merge-with for merging

The merge function merges multiple maps into a single map. If there are the same keys among maps in arguments, latter entries override former entries:

(merge {:a 1 :b 2 :c 3} {:c 4 :d 5 :e 6}) 
;;=> {:a 1, :b 2, :c 4, :d 5, :e 6} 
(merge {:a 1 :b 2 :c 3} {:c 4 :d 5 :e 6} {:c 7 :f 4 :g 6}) 
;;=> {:a 1, :b 2, :c 7, :d 5, :e 6, :f 4, :g 6} 

The merge-with function is more amazing:

(def nicos-fruits 
  {:apple 10 :melon 15 :orange 2 :pear 12} 
  ) 
;;=> #'collection.core...
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