Optics By Example
Optics By Example
Optics By Example

This book is 90% complete

Last updated on 2019-11-20

About the Book

Hi! I'm Chris, I'm writing a book on Lenses and Optics called Optics By Example

Optics By Example is a one-stop-shop guide to optics in functional programming languages, it focuses on explaining how optics work, and how to solve REAL problems with them. Every topic backed up with copious examples and exercises!


Optics have become a wonderful and powerful new way of working with immutable data structures. They're almost a necessity at this point; and the benefits they can bring are immense! However, learning to use lenses can be tricky, and it's not always clear how to build up a large complicated mutation or query from the building blocks of optics. I'm here to help!

This book is great as a first guide to optics, as a reference guide for helping you solve day-to-day problems, and as a springboard into new optics, and ideas which you might not have heard of.

Help me help you by getting early access to the book and giving me feedback on how it's going, and what you'd like to learn!

New chapters releasing every two weeks!



  • What are Optics?
  • LensesRecords
  • Laws
  • Polymorphic Optics
  • Composing Optics (with reference card)


  • Operators (with reference card)
  • Smart lenses
  • Folds
  • Traversals
  • Indexed Optics
  • ISOs
  • Prisms
  • Classy Optics
  • Using Optics with Monads
  • Optics with JSON
  • `generic-lens`
  • Optics with Uniplate
  • Writing Optics without dependencies
  • Optic Encodings
  • Guide to Reading Type Errors
  • Guide to Reading Types

About the Author

Chris Penner
Chris Penner

Hey there! I'm a programmer, coffee lover and acrobat!

I love functional programming and I love writing, seems only natural to bring the two together (especially since it's a bit tougher to match coding and acrobatics!)

Hope you enjoy my book!

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