Functional programming is built around a foundation of well-defined Types, and when you throw in Typeclasses into the mix, you get the love-child that is Algebraic Data Types. In this talk I aim to explore the mathematical foundations of Type theory and how it can be used practically in Scala for wide variety of applications like Machine Learning (Apache Spark MLlib), API design (using Vertx), DSLs and the like.

I will also be introducing the scalacheck library for Property-based testing and how you can quickly validate your ADT domains.

The talk will further deep-dive into how you can utilize the amazing Cats library and Shapeless to build generic libraries around your ADTs, having Circe as a case-study.

Category Theory has been found to have a vast field of applications not limited to programming alone.

In this fun-filled talk (Yes! We promise!) , we want to make the audience fall in love with Math & Category Theory in general, and Haskell in particular.

We will address questions such as below:

• What is the mysterious link between the abstract mathematical field of Category Theory and the concrete world of real-world Programming ? And why is it relevant especially in Functional Programming?
• Most of all, how can You benefit knowing Category Theory ? (Examples in Haskell)

In this talk, we define the principle of functional programming, then go into
detail about what becomes possible by following this principle. In particular,
parametricity (Wadler, 1989) and exploiting types in API design are an essential
property of productive software teams, especially teams composed of volunteers
as in open-source. This will be demonstrated.

Some of our most important programming tools are neglected, often argued away
under a false compromise. Why then, are functional programming and associated
consequences such as parametricity so casually disregarded? Are they truly so
unimportant? In this talk, these questions are answered thoroughly and without
compromise.

We will define the principle of functional programming, then go into
detail about common problems to all of software development. We will build the
case from ground up and finish with detailed practical demonstration of a
solution to these problems. The audience should expect to walk away with a
principled understanding and vocabulary of why functional programming and
associated techniques have become necessary to software development.

In this case study presentation, SumAll's CTO, Todd Sundsted, and Senior Software Engineer, Michael Ho, will discuss the move from Java to Haskell along two parallel paths. First, the business/political story — how SumAll convinced the decision makers, fought the nay-sayers, and generally managed the people impacted by the transition. Second, the technical story — how they actually replaced their Java code with Haskell code. Along the way, they will address their hopes and expectations from transitioning from Java to Haskell, and will conclude with the results they've gained and seen to date.

A virtual cottage industry has sprung up around Purely functional UI development, with many available libraries that are essentially just variants on two distinct approaches: Functional Reactive Programming (FRP), and some form of functional views like "The Elm Architecture". After having worked extensively with each of them, I have found that none of the approaches scale with program complexity. Either they are too difficult for beginners trying to build a hello world app, or they have unpredictable complexity curves with some simple refactorings becoming unmanageably complex, or they "tackle" the scaling problem by restricting developers to a safe subset of FP which becomes painful for experienced developers who start hitting the complexity ceiling.

In this talk I give an overview of the current Purely Functional UI Development Landscape, and then present "Concur", a rather unusual UI framework, that I built to address the shortcomings of the existing approaches. In particular, it completely separates monoidal composition in "space" (i.e. on the UI screen), from composition in "time" (i.e. state transitions), which leads to several benefits. It's also a general purpose approach, with Haskell and Purescript implementations available currently, and can be used to build user interfaces for the web or for native platforms.

The biggest advantage of Concur that has emerged is its consistent UI development experience that scales linearly with program complexity. Simple things are easy, complex things are just as complex as the problem itself, no more. Reusing existing widgets, and refactoring existing code is easy and predictable. This means that Concur is suitable for all levels of experience.

1. For Learners - Concur provides a consistent set of tools which can be combined in predictable ways to accomplish any level of functionality. Due to its extremely gentle learning curve, Concur is well suited for learners of functional programming (replacing console applications for learners).
2. For experienced folks - Assuming you are already familiar with functional programming, Concur will provide a satisfying development experience. Concur does not artificially constrain you in any form. You are encouraged to use your FP bag of tricks in predictable ways, and you are never going against the grain. It's a library in spirit, rather than a framework.

Following Tony and Alois' Introduction to Haskell syntax and tools, we will work through the first few modules of Data61's Functional Programming Course. These modules cover writing functions for the optional and list data types.

We will complete enough exercises to cover basic data types, functions and polymorphism. We'll practice the techniques of equational reasoning, parametricity and type/hole driven development. After completing these modules, you should be able to use the techniques to attempt most other exercises in the repository.

This workshop has the same requirements as Tony's introduction, along with a download of a recent version of the fp-course repository (https://github.com/data61/fp-course).

Testing is one of the most fundamental aspects of being a software developer. There are several movements and communities based on different methodologies with regards to testing such as TDD, BDD or design by contract. However, in the FP community testing is often not a large topic and is often glossed over. While it’s true that testing in functional programming tends to be less important, there should still be more resources on how to create tests that add actual value.

This talks aims to provide exactly that, with good examples on how to leverage property based testing, refinement types and the most difficult part: figuring out how to test code that interacts with the outside world.

Building on the earlier two introductions to functional programming with types, property based testing is the extra verification technique you need to ensure working software. We will work through the patterns of property based testing, starting with simple functions, working up to verification of a larger program.

By the end of this workshop participants will have a better understanding of the advantages of property based tests over example based tests, as well as acquiring the skills and confidence to start applying property based testing techniques to their current work.

This workshop has the same requirements as Tony's introduction, and will require a recent clone of the workshop repository available at https://github.com/markhibberd/property-based-testing-workshop.

Have you ever asked yourself why we only free monads? Turns out there are a lot of other structures that want to be liberated from the constraints of their existence! In this talk, we will investigate what other poor (algebraic) structures we can free from the dirty hands of imperative programmers. Our journey starts with the well-known free monads, but after that we will have a look at all the other interesting structures that can be freed and of course we will also look at what we can do with them.

Intermediate functional programmers often find it daunting to move from examples provided in books and blogs to developing their first fully functioning application. The Queensland Functional Programming Lab at Data61/CSIRO have produced a course for exactly this purpose. Building on the fundamentals, we work through the process of constructing a REST application covering the following topics:

• Package dependencies
• Project configuration
• Application testing & building
• Encoding / decoding messages
• Persistent storage integration
• App state & configuration management
• Error handling & reporting

F# is a relatively new primarily Functional programming language for the .NET platform. It is a statically typed managed functional language that is fully inter-operable with other .NET languages like C#, Visual Basic.NET etc. It builds on the power of Functional Paradigm and combines it with .NET Object-Oriented model enabling the developer to use the best approach for a given problem.

This workshop introduces Functional Programming in F# from ground up. No prior experience in Functional Programming or .NET is needed, familiarity with a mainstream programming language like C++/Java/C# should be enough.

Functional programming (FP) offers several benefits. The code tends to be terse which leads to enhanced developer productivity. FP encourages pure functions which are much easier to reason about and debug, as well as eliminates large class of bugs due to side effect free programming. Moreover, immutability leads to easy parallelization of the code. Algebraic Data Types can be used to express domain object conveniently and control state space explosion.

F# is great practical choice for developing reliable and highly scalable real-world system that are quick and easy to develop due to the design of the language itself combined with the ability of the language to use a large no. of 3rd party libraries designed for the .NET platform.

Unfortunately, support for multiple paradigms often leads to confusion. Newcomers tend to find the transition from object-oriented world to functional world difficult. Moreover, it often leads to abuse where developer tries to use the same old imperative style of coding in a functional language and is unable to take advantage of the features, the language has to offer.

Automated testing is key to ensuring the ongoing health and well-being of any software project,giving developers and users confidence that their software works as intended. Property based testing is a significant step forward compared to traditional unit tests, exercising code with randomly generated inputs to ensure that key properties hold. However, both of these techniques tend to be used at the level of individual functions. Many important properties of an application only appear at a higher level, and depend on the state of the application under test. The Haskell library hedgehog, a relative newcomer to the property based testing world, includes facilities for property-based state machine testing, giving developers a foundation on which to build these more complicated tests.

In this talk, Andrew will give you an introduction to state machine property testing using hedgehog. He'll start with a quick refresher on property based testing, followed by a brief introduction to state machines and the sorts of applications they can be used to model. From there, he'll take you on a guided tour of hedgehog's state machine testing facilities. Finally, Andrew will present a series of examples to show off what you can do and hopefully give you enough ideas to start applying this tool to your own projects. The first set of examples will test a web application written in Haskell. These tests will include: content creation and deletion, uniqueness constraints, authentication, and concurrent transactions. A second set of examples will test an application written in a language other than Haskell to demonstrate that this technique is not limited to applications written in Haskell.

An intermediate knowledge of Haskell and familiarity with property based testing will be beneficial,but not essential. The slides and demo application will be available after the talk for people to study in detail.

Since the first introduction of [Cats Effect](https://typelevel.org/cats-effect/) many things have changed taking its design and performance to a whole new level.

Come join me and learn how to deal with side effects in a pure functional way while abstracting over the effect type and taking composition to the next level. We will review the most important features such as synchronous and asynchronous computations, error handling, safe resource management, concurrency, parallelism and cancellation starting by reviewing the basic concepts.

A journey from statistics computations to composable streaming folds.

Come join me and learn by example about the beauty of generic folds and streaming data. I'll be revisiting these concepts, talking about its origins in Haskell and demonstrating the power of them by showing an example of a program that runs statistics computations using the Fs2 and Origami Scala libraries.

Inevitably, I'll also be talking about performance, concurrency, parallelism and some type classes such as Foldable, Applicative and Monoid, you won't be bored!

This talk starts with setting the context on how the every growing demands of networks (like IOT, SDN) pushes the limits of monitoring applications in terms of scale, availability, resource consumption and accuracy. The heterogeneous nature of networks in enterprises and telecom service providers adds to the scale and resource demands. A J2EE application attempting to fulfill the scale out needs of such a ever growing demanding domain, is pushed to its limits from system design perspective.

The talk presents an evolutionary architecture of moving core components of an existing Network Management J2EE application architecture into Elixir based eco system. It presents the problem chosen to be scaled out and evaluation that led to rewriting the components with Elixir. It also presents the learning in productising a Elixir based subsystem co-existing with a J2EE application.

It concludes with the comparative results in terms of performance, scale out ability, elastic load patterns, resource consumption between old J2EE architectue and new J2EE + Elixir based architecture. It gives a perspective on architectural patterns for transforming J2EE enterprise application in to Elixir based applications.