Functional Programming in Typescript
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Functional Programming in Typescript

A Practical Guide

About the Book

Learn how to write programs the functional way with Typescript and the fp-ts library! This book was written for people who are less or not at all familiar with functional programming. It explains basic functional techniques (including monads) and demonstrates their use in practical examples and projects. In those projects you deploy to the AWS cloud, work with a REST API and store information in a database.

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  • Categories

    • Node.js
    • TypeScript
    • Amazon Web Services
    • Functional Programming
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About the Author

Sam Van Overmeire
Sam Van Overmeire

Professional programmer, focussed on building applications in the Cloud.

About the Contributors

Andrea Simone Costa
Andrea Simone Costa
Francis Godawski
Francis Godawski
Park Junseung
Park Junseung

Table of Contents

  • Acknowledgments
    • About the book cover
  • Introduction
    • Caveat Lector
    • Why FP?
    • Why Javascript?
    • Why Typescript?
    • Why FP-TS?
    • Motivation for this book
    • What you should know
    • Overview
  • Tidbits: Some Useful Javascript and Typescript
    • Requirements
    • Setting up a new project
    • More than one way to build a function
    • Backticks for easy printing
    • The ternary operator
    • Discriminating unions
    • Summary
  • First Steps with Functional Programming
    • What is Functional Programming
    • Pure functions, referential transparency and immutability
    • Writing functional code
    • Writing functional programs
    • Monads
    • Briefly about types again
    • Summary
  • Our First Project: User Registration
    • Defining our types
    • Validation with Either
    • Before we continue: Either or Validation?
    • Creating our user with lifting
    • Bringing it together
    • Change is inevitable - how to cope with it
    • Summary
  • Deploying a monitoring application
    • AWS Lambda and SAM
    • Setting up our project
    • Using the Cloudwatch SDK
    • Monads for asynchronous behavior
    • Transforming our data
    • Synchronous behavior and IO
    • Bringing it all together
    • Extensions
    • A small aside: memoization
    • Key points
    • Summary
  • Testing
    • The types of testing
    • You mentioned TDD?
    • FP and testing
    • Property-based testing
    • Other tools for better code
    • Summary
  • Once more unto the breach: our final application
    • Setting up
    • Writing our first Create Lambda code
    • Core logic of the Create Lambda
    • Bringing it together
    • Creating the Retrieve Lambda
    • DynamoDB
    • Adding the real database
    • Summary
  • Expanding our reservation application
    • Using the Reader Monad for gathering config
    • Using State
    • Better error types
    • Restaurants and sequenceS
    • Choosing configs
    • Exploring some more ideas
    • Summary
  • Rewriting an application
    • The original application
    • Evaluation
    • Improvements overview
    • Our new code setup
    • Validation
    • Dealing with the asynchronous calls
    • Advantages of our functional approach
    • Summary
  • Advanced FP techniques
    • Domain Specific Languages
    • Tagless final
    • Free monads
    • Executable and declarative encoding, algebraic design
    • Summary
  • Conclusion
    • What we learned
    • Where to go from here
  • Appendix A: Additional Concepts
    • Writer
    • These
  • Notes

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