Real World Functional Programming

In this track we'll try to check up on the claims of the functional programming community: how and where are functional languages and concepts used in the real world? How do these concepts add value? What concepts carry their own weight and which ones don't? There may be Monads...

Day of week:

Friday

Location:

Grand Ballroom - Salon A/B

Host:

Werner Schuster

Presentations

End to End Reactive Programming at Netflix

10:40am - 11:30am

By: Matthew Podwysocki , Jafar Husain
Software developer at Microsoft-- Senior Developer at Netflix

What's does a mouse drag event have in common with an Array of numbers?

The answer to this question may surprise you: they are both collections. This key insight holds the key to dramatically simplifying asynchronous programming in Javascript. In this talk you will learn how you can use the familiar Javascript Array methods to create surprisingly expressive asynchronous programs. Using just a few functions, you will learn how to do the following:

Declaratively build complex events out of simple events (ex. drag n' drop)
Coordinate and sequence multiple Ajax requests
Reactively update UI's in response to data changes
Eliminate memory leaks caused by neglecting to unsubscribe from events
Gracefully propagate and handle asynchronous exceptions

In this talk we'll be exploring the Reactive Extensions (Rx) library (https://rx.codeplex.com/) which allows us to treat events as collections. You'll learn about how Netflix uses Rx on the client and the server, allowing us to build end-to-end reactive systems. We'll also contrast Rx with Promises, another popular approach to building asynchronous programs in Javascript.

Caml Trading - Experiences with OCaml on Wall Street

1:45pm - 2:35pm

By: Yaron Minsky
Co-Author "Real World OCaml"

Jane Street is a company that has staked its existence on functional programming. Specifically, we run a large and successful trading business on software written almost entirely in OCaml, a statically typed functional programming language.

Relying on what is, frankly, an obscure corner of the programming language world is an unusual choice that demands some explanation. In this talk, I'll discuss how and why we made that choice, and how we think it worked out. Along the way, I'll explore the demands that trading makes on your technology stack, and explain why we believe that statically typed functional programming in general, and OCaml in particular, are well suited to those demands.

The Functional Programming Concepts in Facebook's Mobile Apps

4:15pm - 5:05pm

By: Adam Ernst
IOS Engineer at Facebook

In this talk, Adam will detail how his team -- who historically used a traditional imperative programming paradigm for rendering News Feed -- encountered spiraling complexities and declining reliability and decided to make the challenging shift to functional, both to the data model and the view layer of News Feed. Adam will walk through the nuances his team faced and the solutions that stemmed from certain challenges. Specifically, he will dive into why his team found it easier to manage and reason about deeply-immutable data structures, and how the team decided to make the shift to a functional framework -- not just for data models, but all the way to the view layer. Adam will walk through the many challenges his team faced and the benefits of the new framework: deeply-immutable data structures that are easier to reason about, a defined flow for state changes enabling greater reliability, and improved testability. This talk will include an inside look at actual APIs and patterns used to render News Feed on iOS.

Presentations

Real World Functional Programming Open Space

11:55am - 12:45pm

Property-Based Testing for Better Code

3:00pm - 3:50pm

By: Jessica Kerr
Scala Developer

Have you ever been stymied in your refactoring by all the test cases you'd have to update? Or read a test and thought, "But WHY that particular result?" Or been bitten in production by a corner case? It always seems like there are too many tests, too few, or both.

Functional thinking to the rescue! In FP, we like to figure out what our code does in all circumstances, not only a few. The verification side of this is Property-Based Testing, and the framework is ScalaCheck.

Come learn the charm of autogenerated test data, the beauty of expressing only what matters, and the challenge of stating what you need without repeating the code under test. Property-based testing isn't only for more tests with less code. It's about constraining your implementation in all the ways that matter and fewer of the ways that don't. These tests can help your software evolve: maximize correctness without hindering flexibility. When 1 test is 100 tests, the number is always just right.

A day in the life of a functional data scientist

5:30pm - 6:00pm

By: Richard Minerich
Director of Research and Development at Bayard Rock

Data science is hard, not just because of the complex algorithms and mathematics, but because it's easy to make a small mistake that can ruin days or even weeks of work. In this talk you'll see how ideas and tools from functional programming can save you time, how they can prevent some of these mistakes, and how I incorporate them into my everyday workflow.