Thu, Nov 16
Aaron W Hsu - Functional Array Funhouse Intensive
How would your make your programs easier to write, inherently parallel, and have high performance across GPUs and CPUs? How about a development methodology that makes agile programming look sluggish and unreliable? How about shrinking the size and complexity of your code base by an order of magnitude, while increasing performance by an order of magnitude? This intensive workshop is designed to demystify the strange and special world of array programming like you may never have seen it before. Iverson-style array programming terrifies some and amazes others, but no one can argue with the results in areas such as finance, energy, education, or medical research. New research has made array programming scalable across a wide array of parallel hardware architectures. Often renowned for remarkably short, concise code that does a tremendous amount, the area of production level, array programming is an often misunderstood area. This workshop will bring you through a whirlwind of array programming concepts by example and case study, opening up the curtains on the original interactive functional programming language in its modern incarnation. You will learn how you can make use of this sometimes mystical world, with an emphasis on the concepts and how to integrate these concepts into a practical, targeted development methodology and ecosystem for maximizing productivity and leveraging the benefits of notational thinking to their full effect. The goal is to let you keep the magic and fun of programming alive while you use that magic for your benefit in the real world.
Ryan Lemmer - Haskell Design Patterns
In this workshop we explore several areas of advances that make up Modern Haskell.
(This is an experiential workshop, we will code together, and explore ideas together from first principles. You will need GHC 7.10 and up.)
Patterns for IO
Experience the 3 styles of IO programming in Haskell, in the order in which they evolved:
* imperative style (the status quo)
* Lazy IO and its limitations
* Iteratee IO, the solution to Lazy IO
As we compare the different styles, we will pay attention to
* what controls evaluation
* space and resource management
* the relationship between producer and consumer
From Foldable, Traversable to Lenses
We follow the evolution of fold and map on lists, to their generalisation over arbitrary types with the Foldable and Traversable type-classes.
The Lens library raises Foldable and Traversable to an even higher level of abstraction. We will see how the Lens library gives a unified vocabulary for traversal of arbitrary data structures.
Functor, Applicative, Arrow, Monad
These data types fall on a spectrum of power and generality (Functor being the most general, and Monad the most powerful). By experiencing how these types differ in the way they compose, we can gain a clearer understanding of where and how each type may be used.
Datatype Generic Programming (bonus material)
This style of Haskell programming is based on a simple technique: instead of defining functions for ad-hoc types, we deconstruct our types into a more fundamental type representation, and then write generic functions against the lower-level type. These generic functions are impervious to changes in the original, higher-level data types.
We will experience datatype generic programming from first principles, and along the way uncover the key ingredient in the magic sauce called GHC.Generics.
Martin Thompson - High-Performance Messaging with Aeron
In this workshop you will learn how to build microservices with Aeron and SBE in Java. Microservices capable of handling millions of messages per second with very low and predictable response times. We will cover some networking theory and the design of Aeron so you know how to use it with mechanical sympathy.
The core design of Aeron uses a new functional data structure and functional concepts. In this workshop we will explore how functional designs applied with mechanical sympathy can result in the highest performance messaging system available.
Erlang & Elixir Factory Lite
Fri, Nov 17
Registration - 30 mins
Bryan Hunter - Elixir by the Bellyful
Elixir makes me happy, and I bet it will make you happy too. OK, but why is that? Elixir is a modern functional programming language with productive “dev joy” tooling, and it sits atop a decades-stable, crazy-scale, battle-tested foundation: the ErlangVM and OTP. In under three years after Elixir reached 1.0 it has already topped big, popular languages like C# on Stack Overflow’s "2017 Most Loved Language” list. After this session you will understand what makes Elixir special, the ecosystem will be illuminated, and you will have the "why, what, and how" knowledge to confidently begin your Elixir journey.
Welcome Address - 15 mins
Coffee/Tea Break - 15 mins
Luis Ferreira - Winter is coming
Yeah, that was a bad pun, but on this talk we’ll go over how to build an umbrella app in Elixir and Phoenix. As a bonus we’ll also cover a few of the differences between umbrella apps and microservices as well as how the Elixir community is moving towards a more thoughtful architecture for apps.
Ravi Mohan - Predator: A Framework for developing programmatic players for Complex Board Games( in Erlang and PureScript)
Summary: An Experience Report on How I'm using Erlang and PureScript to create programmatic opponents aka 'bots' for complex boardgames I love to play but I can't find people to play with!
The number of boardgames that you can whip out at a gathering and expect people to want play is very small.. Monopoly, Snakes and Ladders, and maybe, if you are *very* lucky, Settlers of Catan. And that's about it.
Getting people to play these games is relatively easy.
However the world of boardgames is *much* wider.
There are literally tens of thousands of boardgames that simulate everything from very abstract geometry puzzles to ones that simulate complex economies and political situations.
Some of the latter are used in very unexpected ways, e.g to train spies and military officers.
Here is an example of an interesting game.
A Distant Plain (by GMT Games) is a boardgame for 4 players that put them in the roles of the US military forces, the Afghan government, the Taliban, and Warlords cum drug dealers, all competing for power in Afghanistan.
Here is another
The War of the Ring, a game for 2 players.
"In War of the Ring, one player takes control of the Free Peoples (FP), the other player controls Shadow Armies (SA). Initially, the Free People Nations are reluctant to take arms against Sauron, so they must be attacked by Sauron or persuaded by Gandalf or other Companions, before they start to fight properly ...."
And one more
"The battle of Sekigahara, fought in 1600 at a crossroads in Japan, unified that nation under the Tokugawa family for more than 250 years.
Sekigahara allows you to re-contest that war as Ishida Mitsunari, defender of a child heir, or Tokugawa Ieyasu, Japan's most powerful daimyo (feudal lord)."
What these games have in common
1. They are wonderful games, immersing you into their respective worlds.
2. They have (relative to Snakes and Ladders or Monopoly) complex rulesets, which take effort and time to master.
3. They are rarely played in India.
4. Even when people own them, opponents are almost impossible to find and schedule.
Which means that if you own these games and live in India, getting to actually play these games is close to impossible. Which is a problem.
Being a programmer, I solve this problem by writing programmatic opponents (aka 'bots') to take the place of other players. This involves all kinds of interesting sub problems - game representation, logic processing for rules, building AI 'smarts' for your opponents, gui and event handling etc.
Since I am doing this in my non existent spare time, I use time and effort saving languages, aka functional languages, in my case Erlang (originally Haskell, I'm using this project to learn Erlang) for the backend and PureScript for the front end.
This talk is about the many challenges I faced in building automated game players (and extracting common frameworks/libraries) from them. Since this is an experience report, it is basically a list of lessons learned, victories *and defeats*, what worked *and what didn't work*.
If you can't use FP at work, but are considering doing so on a personal project, or want to learn how to get going on a non-toy FP learning effort, you could benefit from my mistakes and successes.
Khaja Minhajuddin - Building a collaborative painting canvas using Elixir and Phoenix
As the world is moving to parallel computing and real time messaging, we need robust technologies which support these new paradigms. Elixir being built on top of the Erlang VM is a robust and functional programming language which gives us both.
In this talk we will look at the ease with which we can build a massive collaborative painting canvas which allows users to paint in collaboration with others in real time.
Manoj Govindan - Learning Computer Architecture With Erlang
Computer Architecture begins with electronics. As computers are built layer upon layer starting with primitive gates baked into silicon, followed by chips and logic gates, hardware platform including ALU, RAM, cache etc., and so on, so is the study of computer architecture a study of each of these layers of abstraction.
Students of computer architecture usually rely on simulators, often written in Java or similar imperative/object oriented languages, to aid their learning. Here are some examples of such a program:
As an Erlang/functional programming enthusiast studying computer architecture I decided to write my own equivalent tools in Erlang and TypeScript as I went about my learning. I am studying computer architecture and simultaneously writing the required simulators and other tooling in Erlang and TypeScript.
Building such emulators and tools in Erlang and Typescript results in distinctly different architectures. I'll be demoing the simulator I built and talking about lessons learned doing this.
Lunch - 60 mins
Keynote by Robert Virding - 45 mins
Closing Talk - 15 mins
Sat, Nov 18
Registration - 30 mins
The Concurrent Languages of the Future will be Functional by Francesco Cesarini - 45 mins
Welcome Address - 15 mins
Coffee/Tea Break - 15 mins
Bryan Hunter - Poka yoke: Mistake-proofing via Functional Programming
"Poka yoke” (po-kah yo-kay) is a term from Japanese manufacturing that means "mistake proofing". It is a powerful concept (equally powerful in software) in which the design of a system shapes usage so that human error is prevented or corrected before it can cause real harm. In this session we will explore how and why FP maps so well onto the poka yoke concept. We will discuss the merits of mistake proofing over diligence, and rethink our approaches to craft and quality. You will leave with a new lens to evaluate languages, tools, and your own code. Examples in Elixir, Elm, F#, and Idris.
Roger Hui - Proofs, Derivations, Tests
John Hughes and Mary Sheeran in Why Functional Programming Matters  list “algebra as a litmus test” as one of the four salient features of functional programming, and Ken Iverson in Notation as a Tool of Thought  lists “amenability to formal proof” as one of the five important characteristics of notation. Using the language APL, we prove the correctness of some programs, derive simplifications, and illustrate design validation and program test techniques for functional programs.
 Hughes, John, and Mary Sheeran, Why Functional Programming Matters, Code Mesh, London, 2015-11-02 to -04.
 Iverson, Kenneth E., Notation as a Tool of Thought, Communications of the ACM, volume 23, number 8, 1980-08.
Eric Torreborre - Practical eff monad for micro-services
This talk presents how we use the Eff monad at Zalando to structure a REST microservice. Even when programming with functions, modules and components still matter, and I will present a new approach for dependency injection using the Reader monad (classic) and tree rewriting (what?). Then we will see how to specify more precisely several components (authentication, request to other services and database access) with the Eff monad and support additional concerns like logging or asynchronous execution.
Once you get the basic idea, the possibilities are endless! Rate limiting is just another component and another set of effects involving time and state, testing becomes really clean and easy.
Aloïs Cochard - The Tale of Troy
In recent years, the impact of functional programming on mainstream languages has grown significantly.
After conquering server applications and distributed systems,
the paradigm is now conquering the fields of web development and data analytics.
So what remains? The land of system programming.
When Mozilla did release the language Rust in 2012,
it did immediately striked interest from functional programming enthusiasts due to it's strong emphasis on safety.
Even though it currently lacks some advanced features like higher kinded types,
it is built with functional programming principles as it's core.
Like a Trojan horse (or the parasite mushroom after the language is named),
Rust looks like the next C on the outside... while it might actually be closer to Haskell on the inside!
Let's take a tour and discover an other side of system programming by learning together how to do functional programming in Rust.
Calascibetta Romain - Git under the hood with OCaml
Git is one of the most popular tool for a developper and a part of the power of Git is come from some functional concepts. So, it's obvious to implement the Git format with OCaml!
This talk will present the functionnal concepts of Git (like the immutable tree) and show a practical implementation with OCaml step by step. Then, we will explain how can scale an OCaml code to compute a huge Git repository and understand by this way the power of OCaml (and the mix between the functionnal and the imperative way).
At the end, we will show an example of the usability of Git with OCaml with a concrete application.
Riccardo Terrell - Taming and Composing high performance Stream-Oriented Processing Systems for Big Data
Real time applications are dominating the industry! Data is the main ingredient in Internet-based, social media and Internet of things (IoT) systems, which generate continuous streams of events used for real time analytics. This poses a tremendous challenge due to the massive volume of data collected and processed. These event-based Real-time analysis systems can easily process millions of messages per second through new generation solutions by simply defining small flows and then combining them together to create processing graphs. In this talk, will cover the concepts behind high-performance streamed-oriented big data processing systems. We will explore messaging queue systems like Kafka and Akka Streams which let developers define their process workflows at a higher level to define a graph system enabling a high throughput. You will learn how to integrate high performance stream message queues and how to define process workflows in C# and F#.
Lunch - 45 mins
Tony Morris - Functional Programming in Aviation
In this talk & demo, we have a look at some of the low-hanging problems in general aviation and how functional programming can be applied to provide significant improvements in efficiency and air safety. The current solutions to problems such as navigation, traffic/terrain collision avoidance and weight/balance calculations will be demonstrated to the audience, mostly for amusement. More seriously, we will have a look at the legacy that has led to the way things are, and how to improve by applying our programming skills.
We will look at:
- how aviation safety is regulated.
- how aeronautical services are provided to flight operators.
- how aeronautical navigation is conducted and regulated.
- how the weight and balance for a flight is conducted.
- the methods by which aircraft and ground coordinate between each other.
We will see:
- some real (and basic) data management problems in aviation, that very obviously threaten safety, then solve them, using programming.
- we will see a live demonstration of aeronautical navigation methods, investigate incident reports where lives were lost as a result, and consider how our programming skills can yield improvements, possibly even save lives.
- we will conduct a real weight&balance calculation for a flight, then once hilarity inevitably ensues, we will look at the problems that arise by this method, then solve them using data structures and functional programming. Some
of these practical problems are obvious, even to a non-aviator, and the predictable incident reports are the end result.
- finally, we will have a look at a live demonstration of a software defined radio (SDR), receiving ADS-B transmissions from aircraft (live), an AHRS implementation and GNSS receiver using off-the-shelf, low-cost parts. We will look at why these instruments are helpful to aircraft pilots and interact with that device using the Haskell programming language.
Ryan Lemmer - From Haskell 98 to Modern Haskell - Making sense of the Haskell type system
There are several great books and courses that serve as an introduction to functional programming in Haskell. Typically, these introductions focus on the original core of Haskell ("Haskell 98").
However, going from there into real world Haskell systems can be a bewildering experience. This is because Haskell has evolved significantly since Haskell 98. In this talk we will investigate the key advances in the type-system that make up "modern Haskell".
- type-system extensions: Rank-n types, GADTs, functional dependencies, ...
- kind-system extensions: type functions, kind polymorphism, type promotion, ...
By taking a historical perspective we will look at why new language extensions were introduced, and the context in which they first appeared. This approach gives us a layered view of seemingly disparate language features.
We will see that the evolution of the type system has been a steady march from "programming with types" to type-level programming, and ultimately dependently-typed programming in Haskell.
(This talk will draw from the book "Haskell Design Patterns")
Mushtaq Ahmed - Service Discovery using CRDTs
Service Discovery is an important aspect of microservices, particularly when using containers on elastic infrastructure. Most popular approaches for service discovery require a standalone fault tolerant cluster like Consul, Zookeeper or etcd.
If you are already using Akka as a clustering platform for your services, there is an interesting alternative available for Service Discovery. CRDTs, or Conflict-free Replicated Data Types are a relatively new primitive in distributed systems. CRDTs allows concurrent updates without coordination and has provisions for tuning consistency levels. 'Distributed Data' extension natively supports CRDTs on top of Akka-Cluster.
We used CRDTs in Akka to build the service registration and discovery mechanism for TMT's (Thirty Meter Telescope) software platform. TMT will be world's largest optical telescope once operational. The ongoing software work is open source and available on github. We would like to share the details of our implementation and also compare it existing approaches.
Debasish Ghosh - Mining Functional Patterns
Using a programming language that supports first class functional programming doesn’t necessarily imply that the code you write is functional. Functional programming has the nice properties of being compositional - you design smaller abstractions and then reuse them to build larger ones. You use the power of algebraic properties that these abstractions offer to build larger elements of your model out of smaller ones.
However often we find that many code bases designed in a functional programming language are inherently imperative, especially when you are using a multi-paradigm language like Scala or Java. There’s nothing wrong with imperative code, but it lacks the niceties of expression based composition that makes reasoning about your code so much easier. Also assignments used in imperative code are inherent side-effects that are best avoided (or at least minimized) in an expression oriented language.
In this session I will discuss some of my experiences of mining imperative code and refactoring them into functional patterns. You will be surprised to see how much functional goodness can be derived through functional thinking. Algebraic structures like Monoids, Monads and Kleislis are just buried within the reams of imperative statements crying to come out. In an exercise of half an hour we will liberate them and see how the code quality improves from the point of view of modularity, compositionality and simplicity.
Naresh Jain - Array-Oriented Functional Programming in PHP
Array-oriented Programming (AoP) dates back to 1960s.The fundamental idea behind AoP is that operations apply at once to an entire set of values. This allows the programmer to think and operate on whole aggregates of data, without having to resort to explicit loops of individual scalar operations. At ConfEngine.com, a platform for organising and managing technical conferences/events, we've been heavily influenced by the APL style of AoP. In our context, this means each function focuses on applying one transformation to an immutable array (ordered-map) and then spitting out a new array, which can be piped to another function thus achieving functional composition. This has allowed us to build a very modular, decoupled design, which is extremely simple to reason about.
If you think of typical web-apps, they are generally CRUD applications. Data comes in, you apply a set of transformation and you pass it to someone else via an API or you save/query a data store. And on the way out, you get data from somewhere (data-store, API, etc.), apply a set of transformations and render the transformed data as HTML or JSON. Now we can visualise most web-apps using standard Pipe-and-Filter Architecture. With this, applying some of the functional programming concepts becomes more intuitive.
At ConfEngine.com, we use the standard LAMP stack. We've used PHP's philosophy of shared-nothing-architecture to address concurrency and scalability concerns. PHP itself has all the basic ingredients required for Functional Programming - first-class, higher-order functions, lambda, closures, partial functions, recursion and so on. We use array (ordered-map) to hold the data. PHP provides 79 array functions that allows you to do pretty much everything you need to in terms of transforming arrays including map, reduce, filter, merge and so on. One needs to be careful, but most of these are pure, higher-order functions.
If you are interested to learn more about AoP, I'll give a walk through of our design. Also I'll take a couple of problems to explain how to think in terms of AoP and how its really helps with functional programming.
Paweł Szulc - Going bananas with recursion schemes for fixed point data types
In 1991 Erik Meijer, Maarten Fokkinga, and Ross Paterson published "Functional Programming with Bananas, Lenses, Envelopes and Barbed Wire." This paper is a classic one, widely recognizable in the FP community. Constructs described - known as recursion schemas - have real world applications. Strictly speaking, explicit recursion is the ‘goto’ of pure functional programming. Recursion schemas provide same level of sanity as loops did for structural programming back in the day.
Over the years a lot of the progress have been made. Papers like "Recursion schemes from comonads" by Tarmo Uustalu, Varmo Vene & Alberto Pardo or "Unifying Structured Recursion Schemes" by Ralf Hinze, Nicolas Wu & Jeremy Gibbons - pushed the concept forward.
This talk is about generalization of a very specific recursion schema (called catamorphism) over fixed point data type. After providing introduction the concept of catamorphism, we will jump straight to fix point data types trying to solve some real-world problems. Code examples are in Scala. Code examples use Matryoshka - which is an open sourced project design to generalize folds, unfolds, and traversals for fixed point data structures in Scala.
Coffee/Tea Break - 15 mins
Manuel Chakravarty - Haskell SpriteKit - a Purely Functional API for a Stateful Animation System and Physics Engine
Graphics, animation, and games programming in Haskell faces a dilemma. We can either use existing frameworks with their highly imperative APIs (such as OpenGL, Cocos2D, or SpriteKit) or we waste a lot of energy trying to re-engineer those rather complex systems from scratch. Or, maybe, we can escape the dilemma. Instead of a Haskell program directly manipulating the mutable object-graph of existing high-level frameworks, we provide an API for purely functional transformations of a Haskell data structure, together with an adaptation layer that transcribes those transformations into edits of the mutable object-graph.
I this talk, I will explain how I used this approach to architect a Haskell binding to the animation system and physics engine of Apple’s SpriteKit framework. I will discuss both how the binding is structured and how it achieves the translation of Haskell side changes to SpriteKit and vice versa, such that it is sufficiently efficient. Moreover, I will demonstrate by example how to use the Haskell library to implement a simple game.
Arthur Kushka - Recursion schemes and fixed point data types
Its always challenge to build a good abstraction during work on library. Library codebase must be flexible and modular when user code must be clean and easy understandable. One of variants to build API between library and customer its Free evaluation approach. In that case you as developer is free to interpret customer actions as you want and customer is free to define actions as he want. In my talk I will show how to build API based on recursive abstract data types, describe why its cool and demonstrate some tricks on type system to make customer experience with library better.
Nikhil Tibrewal - Scio – Scala DSL for Apache Beam
Apache Beam (based on Google’s Dataflow Model) provides a simple, unified programming model for both batch and streaming data processing. If only it wasn’t so unfamiliar and verbose for our Scala engineers. Learn how Scio leverages Scala’s type system, macros and functional paradigm to provide more engineer-friendly and type safe API.
Dhaval Dalal - Code Jugalbandi
In Indian classical music, we have Jugalbandi, where two lead musicians or vocalist engage in a playful competition. There is jugalbandi between Flutist and a Percussionist (say using Tabla as the instrument). Compositions rendered by flutist will be heard by the percussionist and will replay the same notes, but now on Tabla and vice-versa is also possible.
In a similar way, we will perform Code Jugalbandi to see how the solution looks using different programming languages and paradigms. This time the focus of code jugalbandi will be on solutioning in two different paradigms - functional programming and array-oriented paradigm.
During the session, Morten and Dhaval will take turns at coding the same problem using different languages and paradigms. There would be multiple such rounds during the Jugalbandi.
Maria Livia Chiorean - The path to generic endpoints using Shapeless
Programming in Scala is sometimes very time consuming. Finding the most efficient way to solve a problem can end up in days of frustration. This talk is a story of trail and error with a twist at the end. It's a story of API endpoints, generic programming, Shapeless and what happens when they all come together. Everything with examples and plenty of code.
Closing Keynote - 45 mins
Closing Talk - 15 mins
Sun, Nov 19
Manuel Chakravarty - Functional Programming in Swift
Swift’s strong functional programming support generates a lot of interest in adapting functional programming techniques to improve designing, developing, and maintaining Cocoa applications. This workshop will help you unlock this potential.
We will explore the foundations of functional programming and how functional programming helps to improve software development. We will start by discussing the main goals of functional programming, followed by surveying Swift’s language features that support functional programming. Then, we will look at how to put functional programming principles into practice using Swift. We will focus on immutable data structures, value types, and functional reactive programming.
= Value types
One of the biggest changes in the transition from Objective-C to Swift is the new type system. This change is at the heart of Swift’s language design, from optionals over value types to constrained generics, and to truly understand the language, a thorough understanding of its type system is indispensable. We will survey these type system features with special attention to value types. We will discuss how structs and enums in Swift can be used to help avoid bugs by design and how immutable data structures help to avoid unwelcome side effects.
= Functional reactive programming
Functional reactive programming (FRP) promises to replace unstructured side effects by structured change propagation in response to user input, network events, sensor activity, and similar. Typically explained by way of sophisticated, but often also complex functional reactive programming frameworks, such as ReactiveCocoa and RxSwift, it can be difficult to see the simple principles underlying functional reactive programming. In fact, these principles are sufficiently simple that we can explain them by building a functional reactive programming library from scratch.
We will discuss how we can construct our own lightweight functional reactive programming library out of simple components using Swift’s support for protocol-oriented programming. Moreover, we will discuss how to use this library to design and implement the change propagation between the model and view components of a Cocoa app.
All of this is illustrated with hands-on coding exercises based on simple iPhone application that incorporates the discussed techniques.
Building Distributed Fault-tolerant Applications by Francesco Cesarini