Learning (from) Haskell - An experience report

Functional programming as a programming style and discipline is useful even in languages which are not pure functional languages. By practising programming in a pure functional language like Haskell, programmers can drastically improve the quality of code when coding in other languages as well.

The talk is based on first hand experience of using Haskell in internal courses in our organisation to improve code quality.

This talk will cover Gofer (one of the earliest variants of Haskell) as a teaching tool, including the choice of the language, the features from Haskell that should (and shouldn't) be covered and the obstacles and benefits of the exercise.

 

 
 

Outline/structure of the Session

  1. The context - in what environment are the contents of this talk relevant
  2. Why we felt the need for inculcating functional programming habbits in our developers - The desirable characteristics of functional programming style and functional code
  3. Why Haskell? (And why not Scheme).
  4. Introducing Gofer
  5. What aspects of Haskell we focused on (and what we left out)
  6. Applying the learnings to other languages - real world before and after examples
  7. Obstacles and benefits

Learning Outcome

Whether learning functional programming is useful for you or your developers, the effort and investment that would be needed and the benefits you will derive from it.

Target Audience

CTO, Team Leads, Passionate programmers

schedule Submitted 2 years ago

Comments Subscribe to Comments

comment Comment on this Proposal
  • Dhaval Dalal
    By Dhaval Dalal  ~  1 month ago
    reply Reply

    Hi Aditya,

       I am kind of in between - is this talk or more of an experience report that you intend to share?  I think it suits more to be an XR as it would be interesting to see - the journey - did you try this with OO programmers (if at all) ? How Haskell helped in developing better insights to the problems in existing codebase (esp in connection with #5 above) ? and what did you observe during the transition?

    thanks

    • Aditya Godbole
      By Aditya Godbole  ~  2 years ago
      reply Reply

      It is in some sense an XR. But it will also cover technical aspects of what functional programming means outside a pure functional language.

      I will also cover which features from the functional world, if adopted as a discipline, give the most bang for the buck.

      Also, the two sides of the coin, for me, are not OO vs Functional, but Imperative vs Functional. Whether the imperative code was OO is not relevant to this discussion.

      I will also include a few before and after examples in languages like Python, Javascript and Ruby, to illustrate the difference that this exercise made in the typical code produced by programmers.

      • Dhaval Dalal
        By Dhaval Dalal  ~  1 month ago
        reply Reply

        Thanks Aditya for the clarification: Imperative -> Functional.  I was just proding to find where you were coming at this from and hence the question.  It would be nice to see the before -> after transformation after applying the learnings from Haskell.  

        As I understand, the technical aspects and features in the FP land are underpinning this, and I think blending them (not sure if you meant it that way) with the examples from your experience will leave the audience inspired to try it out.  what do you think?

         

        • Aditya Godbole
          By Aditya Godbole  ~  2 years ago
          reply Reply

          Hopefully the before/after examples will give a glimpse of how maintainable code can be written after the discipline picked up by practising functional programming in haskell is applied to other languages. I stress on the word discipline because that is what is required when one is writing in an imperative language. That should serve as the motivation for audience to write code in haskell.

          The bottom line of the talk is this - in haskell you write code in a certain way because there is no choice or because that is the idiomatic way or the path of least resistance. By practising in haskell, you carry forward that discipline to other languages not because you have to, but because you start seeing the value (pun not intended). 

          • Dhaval Dalal
            By Dhaval Dalal  ~  1 month ago
            reply Reply

            Hey Aditya,

               Can you make this as an XR and refactor "Process" section to deliver it from that perspective?

            Thank-you,

            Dhaval.

             

            • Aditya Godbole
              By Aditya Godbole  ~  2 years ago
              reply Reply

              Done. Is there anything else in particular you want to see changed?

              • Naresh Jain
                By Naresh Jain  ~  2 years ago
                reply Reply

                Thanks Aditya. Can you please update your title to Learning (from) Haskell - An Experience Report. This would be more clear to the participants.

  • vimalk
    By vimalk  ~  2 years ago
    reply Reply

    i would not miss this talk!!


  • Morten Kromberg
    Morten Kromberg
    schedule 2 years ago
    Sold Out!
    60 mins
    Demonstration
    Beginner

    APL is a member of the family of languages that are approaching middle age (Ken Iverson’s book titled “A Programming Language” was published in 1962). APL was very influential in the 60’s and 70’s, and widely used to deliver “end user computing” - but although the REPL, dynamic scope and lack of a type system endeared APL to domain experts, it also drew fire from computer scientists, most famously when Edsger Dijkstra declared that “APL is a mistake, carried through to perfection. It is the language of the future for the programming techniques of the past it creates a new generation of coding bums.”

    Dyalog is a modern, array-first, multi-paradigm programming language, which supports functional, object-oriented and imperative programming based on an APL language kernel. Dyalog allows people with good ideas – from bright high school students to PhDs – to contribute directly to the software development process using a notation which fits comfortably with those used in their own domains. Subject matter experts can write prototypes or, with suitable training and/or support, highly efficient, parallel and robust code that can be embedded in high-performance production applications.

  • Venkat Subramaniam
    Venkat Subramaniam
    schedule 2 years ago
    Sold Out!
    60 mins
    Keynote
    Intermediate

    It's been around for a long time, but everyone's talking about it all of a sudden. But why and why now? We've been

    programming in languages like Java for a while, quite well. Now we're asked to change and the languages themselves

    are changing towards this style of programming. In this keynote, a passionate polyglot programmer and author of

    "Functional Programming in Java: Harnessing the Power of Java 8 Lambda Expressions" will share the reasons

    we need to make the paradigm shift and the pure joy—the benefits—we will reap from it.

  • Liked Rahul Goma Phulore
    keyboard_arrow_down

    Object-functional programming: Beautiful unification or a kitchen sink?

    Rahul Goma Phulore
    Rahul Goma Phulore
    schedule 2 years ago
    Sold Out!
    60 mins
    Talk
    Advanced

    Scala began its life as an experiment to “unify” object-oriented programming and functional programming. Martin Odersky believed that the differences between FP and OO are more cultural than technical, and that there was a room for beautifully unify various ideas from the two into one simple core.

    How successful has Scala been in its goals? Is it the like “the grand unified theory of universe” or like the infamous “vegetarian ham”? [1]

    In this talk, we will see just how Scala unifies various ideas – such as type-classes, algebraic data types, first-class modules, functions under one simple core comprising of traits, objects, implicits, and open recursion. We will how this unification unintendedly subsumes many concepts that require seprate features in other languages, such as functional dependencies, type families, GADTs in Haskell. We will see how this has given a rise to a new “implicit calculus”, which could lay a foundation for next generation of generic programming techniques.

    We will see that this unification comes at a certain cost, wherein it leads to some compromises on both sides. However many of these trade-offs are particular to Scala (largely due to the JVM imposed restrictions). The goal of unification is still noble, and we need not throw the baby out with the bathwater.

    [1]: https://twitter.com/bos31337/status/425524860345778176

  • Rahul Goma Phulore
    Rahul Goma Phulore
    schedule 2 years ago
    Sold Out!
    45 mins
    Talk
    Intermediate

    Futures and promises are no strangers to most programmers. They have made their way into major mainstream languages, including but not limited to, Java, C#, JavaScript, and C++.

    This abstraction however is typically dreaded due to the way they’re typically done. Most manifestations lead to the insidious callback hell, and some, like Java’s, are incredulously limited.

    Why can’t we keep our simple, straightforward code, and still have the concurrency benefits of futures and promises?! Turns out we can. Functional programming is here to the rescue! We will see how the seemingly obscure abstractions like monads, delimited continuations allow us to do just that.

    We will also go over some syntactic-transformation based approaches (basically, macros), such as C#’s async-await, and see how it compares with the functional approaches discussed earlier.

  • Liked Rahul Goma Phulore
    keyboard_arrow_down

    You could have invented monads!

    Rahul Goma Phulore
    Rahul Goma Phulore
    schedule 2 years ago
    Sold Out!
    45 mins
    Tutorial
    Intermediate

    Of all the computational abstractions that functional programming has brought to the table, monads seem to be disproportionately more popular than the rest. (Or should I say, notorious?) The web is filled with monad tutorials, ranging from those using pure mathematics to explain the idea, to those using (half-baked) metaphors like burritos and space-suites. One might think this should make it relatively easy to grok monads. Unfortunately, many of these tutorials do a rather poor job, and do not help students gain an intuition for the idea. This has resulted in an unparalleled FUD around monads.

    A part of difficulty people have when learning functional programming abstractions such as monads comes from the fact that, this new way of thinking involves looking for abstraction opportunities in places they’re not used to.

    In this talk, I will start by presenting some seemingly unrelated day-to-day code examples. I will underline the problems common to all of them, and then we will all together derive a general abstraction applicable to all of them. If you can follow through till the last bit (and in my experience, most of the audience does), you have not only understood but essentially re-invented monads!

  • Bodil Stokke
    Bodil Stokke
    schedule 2 years ago
    Sold Out!
    60 mins
    Keynote
    Beginner

    In this talk, we'll explore why some technologies end up inexplicably dominating our field while others fade away despite their obvious merits. What will it take for the languages we care about to succeed, and what are the consequences of success? Let's apply a broad perspective to the mess we've made of modern computer science, and explore our options for getting the situation back on track through a careful examination of history, science and ponies.

  • Liked Amit Dev
    keyboard_arrow_down

    A practical introduction to Monads

    Amit Dev
    Amit Dev
    schedule 2 years ago
    Sold Out!
    30 mins
    Demonstration
    Beginner

    Some people find it hard to understand Monads (like pointers in C). But it is actually a simple concept (like pointers in C). In this session we try to understand Monads and why they are useful through examples. It is purely from a practical point of view and no theory is covered.

  • Liked Venkat Subramaniam
    keyboard_arrow_down

    Haskell for Everyday Programmers

    Venkat Subramaniam
    Venkat Subramaniam
    schedule 2 years ago
    Sold Out!
    90 mins
    Talk
    Intermediate

    I learn different languages not to make use of them, but to program in my current languages in a better way. As we adapt functional style of programming in mainstream languages, like Java, C#, and C++, we can learn a great deal from a language that is touted as a purely functional language.

    Haskell is statically typed, but not in a way like Java, C#, or C++. Its static typing does not get in the way of productivity. Haskell quietly does lazy evaluation and enforces functional purity for greater good. Everyday programmers, like your humble speaker, who predominantly code in mainstream languages, can greatly benefit from learning the idioms and style of this elegant language. The next time we sit down to crank out some code in just about any language, we can make use of some of those styles, within the confines of the languages, and move towards a better, functional style.

  • Liked Venkat Subramaniam
    keyboard_arrow_down

    Designing with Lambda Expressions in Java

    Venkat Subramaniam
    Venkat Subramaniam
    schedule 2 years ago
    Sold Out!
    90 mins
    Talk
    Intermediate

    As Java programmers we have used a number of design patterns and design techniques. With the introduction of lambda expressions, we now have some more sharper tools in our design toolbox. Come to this presentation to learn how we can implement some elegant design ideas with lambda expressions. We will learn about these design techniques, not using diagrams, but by realizing the ideas in code.

  • Mushtaq Ahmed
    Mushtaq Ahmed
    schedule 2 years ago
    Sold Out!
    60 mins
    Tutorial
    Intermediate

    Haskell has populairzed typelcasses a principled way to add ad-hoc extensions on existing data types. They allow you to 1) add new operations on existing data types and 2) support new data types on existing operations, and thus solve the famous "expression problem".

    There is a lot of similarily between typeclasses and Java good practices of programming to interfaces and preferring composition over inheritance. The missing link is the implicit dictionary passing which allows haskell to be much more concise and expressive.

    In this tutorial, we will look at how Scala adopts typeclasses by adding the missing link of implicits.

  • Liked Ryan Lemmer
    keyboard_arrow_down

    Realtime Distributed computing: dealing with Time and Failure in the wild

    Ryan Lemmer
    Ryan Lemmer
    schedule 2 years ago
    Sold Out!
    45 mins
    Experience Report
    Intermediate

    There is a growing need for scalable, realtime business systems that are continuously running and highly-available. Two very different frameworks/approaches you could use to build such systems are Storm and Akka.

    Systems created with Storm or Akka are distributed, at runtime, on as many machines as you choose. The inherent concurrency implied by this brings the issues of State, Time and Failure into sharp focus. Functional programming has much to say about dealing with state and time; not surprisingly, both Storm and Akka have strong roots in functional languages (for Storm it is Clojure, and for Akka, Scala).

    In this talk we'll explore the core concepts and challenges of distributed computation; the role of functional programming in concurrent distributed computing; we'll take a look at Storm and Akka, by example, and see that as different as these 2 approaches are, the underlying difficulties of distributed computation remains evident in both: dealing with time, and dealing with failure.

  • Liked Debasish Ghosh
    keyboard_arrow_down

    Property based testing for functional domain models

    Debasish Ghosh
    Debasish Ghosh
    schedule 2 years ago
    Sold Out!
    45 mins
    Talk
    Intermediate

    Manual testing is something that's error prone, incomplete and impossible to replicate on a large scale. We have instead been using xUnit style of testing for quite some time now. This approach has a number of drawbacks like (a) We need to write test cases by hand which again doesn't scale for large systems (b) We may miss out some of the edge cases (c) Safeguarding missing cases with coverage metrics doesn't help, since metrics are mostly based on heuristics (d) maintaining test cases and test data is a real pain.

    In property based testing we write properties and not low level test cases. And let the system generate test cases which validate such properties. There are 2 main advantages with this approach:

    1. You think in terms of properties (or specifications) of the domain model which is the right granularity to think about
    2. You don't need to manage test cases, which is completely done by the system that generates a large collection of test data

    This approach is ideal for the functional programming paradigm, which focuses on pure functions. Using functional programming it's easier to reason about your model - hence it's easier to test functional programs using properties. In this talk I will take some real world examples of property validation and verification using scalacheck (the property based testing library for Scala) and a real world domain model.

  • Mushtaq Ahmed
    Mushtaq Ahmed
    schedule 2 years ago
    Sold Out!
    60 mins
    Tutorial
    Beginner

    Objected oriented languages like Scala support the paradigm of programming with functions. How does it work? The language has to conceptually map functions to objects. This tutorial will explain this idea by starting with a simple Java-like code and progressively refactor it to make use of higher order functions. As a result, you will learn about a few syntax sugars and also the cost implication of using objects to represent functions.

  • Mushtaq Ahmed
    Mushtaq Ahmed
    schedule 2 years ago
    Sold Out!
    60 mins
    Demonstration
    Intermediate

    Sync, Async, Blocking, Non-Blocking, Streaming are the buzzwords in the reactive programming world. This talk will attempt to attach some meaning to them. It will also demo the performance and resource consumption patterns for blocking-io, Scala Futures and RxJava Observables for comparable programs. Finally, a command line application that consumes twitter streams API will demo what is possible using the new reactive abstractions.

  • Anil Wadghule
    Anil Wadghule
    schedule 2 years ago
    Sold Out!
    45 mins
    Talk
    Beginner

    As Object Oriented programmers, we follow SOLID Design Principles for improving OO design of our applications.

    If you take the SOLID principles to their extremes, you arrive at something that makes Functional Programming look quite attractive.

    Objects are merely a poor man's closures. And ultimately Closures are a poor man's objects.

    This talk explains about how applying SOLID Design principles like Single Responsibility Principle (SRP) leads to many small classes. Furthermore, if you rigorously apply the Interface Segregation Principle (ISP), you'll eventually arrive at the ultimate Role Interface: an interface with a single method.

    If you apply the SRP and ISP like that, you're likely to evolve a code base with many fine-grained classes that each have a single method.

    Objects are data with behaviour. Closures are too are data with behaviour.

    This talk will enlighten how applying Object Oriented Design Principles to their extreme will lead you to Functional Programming.

    It's necessary for Object Oriented programmer to understand why Functional programming makes sense.

    At the end, this talk will also cover essential basics of Functional programming needed to be known for every Object Oriented Programmer.

  • Liked uday
    keyboard_arrow_down

    Why functional programming and BIG Data go hand in hand

    uday
    uday
    schedule 2 years ago
    Sold Out!
    45 mins
    Talk
    Intermediate

    My session will focus on why functional programming and big data go hand in hand covering the following aspects with use cases from my experience report:

    • Parallelize Code : Functional programming makes it easier to parallelize code, so even if a single operation may take more time to run in one thread, the overall performance can be better due to parallelism.
    • Seamless integration: Modern programming paradigms like functional programming, proven to provide the best scalability for cloud computing, are necessary to ensure cost-efficient performance for big data. Functional programming
      can be efficiently parallelised owing to it’s mathematical syntax thus allowing a seamless integration between algorithms
      and economic models.
    • Scalable Architecture: Functional languages encourage scalable software architectures is because of the fact that they, from the bottom up, eliminate as much shared state as possible from a language. This leads to scalable "micro" components.  Those micro components then scale naturally into larger components.
    • Efficient distributed code: Functional programming makes it much easier to write correct and efficient distributed code due to immutable data structures and statelessness.
  • Liked Ramakrishnan Muthukrishnan
    keyboard_arrow_down

    An introduction to Continuation Passing Style (CPS)

    Ramakrishnan Muthukrishnan
    Ramakrishnan Muthukrishnan
    schedule 2 years ago
    Sold Out!
    60 mins
    Tutorial
    Intermediate

    Traditionally functions return some value. Someone is waiting for that value and does some computation with it. This "someone" is called the continuation of this value. In a normal functional call, the continuation is "implicit". In the "continuation passing style" (hence forth called with the short form, CPS), we make the continuations explicit. In this style, function definitions take an extra argument called "continuation" and it never return. The "return value" of the function 'continues' by passing this value as an argument to the continuation. Continuations are sometimes called "gotos with arguments".

    CPS is used as an intermediate stage while compiling a program since it makes the control structure of the program explicit and hence can be converted easily to machine code. Another feature of a CPS-transformed function is that it is tail-recursive even if the original function was not written in a tail-recursive style.

    Continuations enable a programmer to build new control operators (if the language's built-in operators does not already provide the control operators the programmer need).

  • Liked Kishore Nallan
    keyboard_arrow_down

    Applying functional programming principles to large scale data processing

    Kishore Nallan
    Kishore Nallan
    schedule 2 years ago
    Sold Out!
    45 mins
    Talk
    Intermediate
    At Indix, we deal with a stream of unstructured and constantly changing data. This data is processed through a series of systems before being fed as structured input to our analytics system. In this talk, I will walk through our experience of building a large scale data processing system using Hadoop that's focused on immutability, composition and other functional programming principles.
  • Shakthi Kannan
    Shakthi Kannan
    schedule 2 years ago
    Sold Out!
    60 mins
    Talk
    Beginner

    This talk is an introduction on lambda calculus and will address the foundations of functional programming languages.

    We will learn the building blocks of lambda calculus - syntax, rules, and application.

  • Shashi Gowda
    Shashi Gowda
    schedule 2 years ago
    Sold Out!
    90 mins
    Tutorial
    Beginner

    Code used during the talk: https://github.com/shashi/fuconf-talk
    Slides: https://docs.google.com/presentation/d/16Xfqd-xU8y2JEN0TIcacDoYnp0b5-W7ESDB5v1SmcXs/edit#slide=id.p

     

    Elm is a strongly typed functional reactive programming (FRP) language that compiles to HTML, CSS, and Javascript. In Elm, the Signal type represents a time-varying value--things like mouse position, keys pressed, current time are signals. With Signals, one can write terse code that is isomorphic to a dataflow diagram of the app. The code hence feels natural and is 100% callback free. All this, with powerful type inference.

    This talk is an introduction to FRP. It explores functionally composing graphics and UIs, and creating interactions and animations with the Signal type. There will also be an overview of Elm’s execution mechanism and the time traveling debugger: a consequence of Elm's purely functional approach.

    While instructive, it will be good fun too, in the spirit of Elm.