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Scala Functional Programming Patterns

You're reading from   Scala Functional Programming Patterns Grok and perform effective functional programming in Scala

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Product type Paperback
Published in Dec 2015
Publisher
ISBN-13 9781783985845
Length 298 pages
Edition 1st Edition
Languages
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Author (1):
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Atul S. Khot Atul S. Khot
Author Profile Icon Atul S. Khot
Atul S. Khot
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Table of Contents (13) Chapters Close

Preface 1. Grokking the Functional Way FREE CHAPTER 2. Singletons, Factories, and Builders 3. Recursion and Chasing your Own Tail 4. Lazy Sequences – Being Lazy, Being Good 5. Taming Multiple Inheritance with Traits 6. Currying Favors with Your Code 7. Of Visitors and Chains of Responsibilities 8. Traversals – Mapping/Filtering/Folding/Reducing 9. Higher Order Functions 10. Actors and Message Passing 11. It's a Paradigm Shift Index

A view to a collection


Databases have views. A database view works just like a table; however, the table never exists. It is just an illusion. A view is only a stored query, which is run when the view name is referenced:

Mysql> CREATE VIEW first_last AS SELECT first_name, last_name FROM NAMES WHERE last_name LIKE ('k%');
mysql> SELECT first_name FROM first_last;

The view first_last query is backed by the result set of a query, on a real table, NAMES. We can select only the columns of interest and apply some transformations on them.

Scala collection views are similar. We will soon be giving a close look to functional transformation. However, to get a taste, the following is an example:

We need to assign a temporary password to a user. We have a list of randomly generated passwords. We need to pick one.

Our validation rules are:

  1. A password cannot be empty.

  2. It must have at least an uppercase letter.

  3. It should have a numeric character.

  4. It must have a special character.

  5. It must have five or more...

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