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Functional Python Programming, 3rd edition

Functional Python Programming, 3rd edition

By : Steven F. Lott
4.5 (28)
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Functional Python Programming, 3rd edition

Functional Python Programming, 3rd edition

4.5 (28)
By: Steven F. Lott

Overview of this book

Not enough developers understand the benefits of functional programming, or even what it is. Author Steven Lott demystifies the approach, teaching you how to improve the way you code in Python and make gains in memory use and performance. If you’re a leetcoder preparing for coding interviews, this book is for you. Starting from the fundamentals, this book shows you how to apply functional thinking and techniques in a range of scenarios, with Python 3.10+ examples focused on mathematical and statistical algorithms, data cleaning, and exploratory data analysis. You'll learn how to use generator expressions, list comprehensions, and decorators to your advantage. You don't have to abandon object-oriented design completely, though – you'll also see how Python's native object orientation is used in conjunction with functional programming techniques. By the end of this book, you'll be well-versed in the essential functional programming features of Python and understand why and when functional thinking helps. You'll also have all the tools you need to pursue any additional functional topics that are not part of the Python language.
Table of Contents (18 chapters)
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Preface
16
Other Books You Might Enjoy
17
Index

6.2 Reductions and folding a collection from many items to one

We can consider the sum() function to have the following kind of definition. We could say that the sum of a collection is 0 for an empty collection. For a non-empty collection, the sum is the first element plus the sum of the remaining elements:

 (| { 0 if n = 0 sum ([c0,c1,c2,...,cn]) = | ( c0 + sum ([c1,c2,...,cn]) if n > 0

We can use a slightly simplified notation called the Bird-Meertens Formalism. This uses [c0,c1,...cn] to show how some arbitrary binary operator, , can be applied to a sequence of values. It’s used as follows to summarize a recursive definition into something a little easier to work with:

sum ([c0,c1,c2,...,cn]) = + ∕[c0,c1,c2,...,cn] = 0+ c0 + c1 + ...+ cn

We’ve effectively folded the + operator between each item of the sequence. Implicitly, the processing will be done left to right. This could be called a ”fold left” way of reducing a collection to a single value. We could also imagine grouping the operators from right to left, calling this a ”fold right.” While some compiled...

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