Beginner-friendly introduction to Free Monads by Dmitrii Kovanikov

In this talk, I'd like to look into several diverse problems, their possible solutions and discuss drawbacks of with these ad-hoc solutions. After that, I'm going to introduce the idea of Data-Oriented Programming. I'll build the concept of Free Monad from ground up and explain the uniform approach for all the demonstrated different problems. I'm also going to discuss the drawbacks of Free Monads.

About our speaker - Dmitrii Kovanikov

I do tons of open-source work including mentoring people, creating educational resources and maintaining projects. I'm an author and maintainer of dozens OSS libraries and applications. I also had been teaching Haskell at ITMO University for several years to undergrad students. I love making complicated topics accessible and sharing my knowledge with others!

Personal page and blog: https://kodimensional.dev

Event details: https://www.meetup.com/bay-area-haskell-user-group/events/288894864/

Also available on my YouTube channel

Server-side Swift State Of The Union By Tim Condon

This talk takes a step back and looks at how server-side Swift is doing.

We'll cover the recent changes due to async/await, how it compares to other languages and what the future holds.

About our speaker

Tim is a Swift developer from Manchester, UK and part of the Vapor Core Team. He's the server-side Swift team lead at raywenderlich.com and has written the unofficial-official book on Vapor with the founders of the framework.

He founded Broken Hands a few years ago and delivers talks and workshops on Vapor and server-side Swift around the world.

He also co-organises the ServerSide.swift conference - the world’s first and only conference focused on server-side Swift.

Follow Tim on Twitter and do visit his website.

Event details: https://www.meetup.com/swift-language/events/285667200/

For more information about Swift Language User Group (San Francisco) visit: https://www.sfswift.com

Also available on YouTube

Supercharging Data with SQL and Haskell by Ozgun Ataman

We will be sharing the backstory/behind-the-scenes of a data engineering tool we’ve created over the past 5 years called “napkin” that lets data science/engineering teams construct sophisticated data transformations in SQL, manage lots of complexity as their pipelines grow and lean on modern databases like BigQuery to effortlessly scale up to massive volumes. We’ll soon be releasing napkin publicly (for free) and are excited to be making a noteworthy contribution to the broader “data engineering and analytics” community. We look forward to describing how Haskell has been a natural force multiplier in enabling sophistication on top of SQL and modern analytics databases.

About our speaker

Ozgun Ataman, CEO at Soostone, where we’ve been intensive commercial users of Haskell for the past 10 years focusing on production applications around machine learning, business optimization and analytics.

Slides: https://drive.google.com/file/d/1JXT4yEHWavdgkIioh5cYmZMw02fKUXQz/view?usp=sharing

Event details: https://www.meetup.com/Bay-Area-Haskell-Users-Group/events/284148984/

Recording also available on YouTube

Namespaced DeBruijn Indices By Gabriella Gonzalez

This presentation describes a simple and elegant solution for avoiding name capture in interpreted languages that also improves the readability of inferred types and β-reduced normal forms. The name for the trick is "namespaced DeBruijn indices" because it combines the best features of both a named representation and De Bruijn indices.

About our speaker

Gabriella (a.k.a. Gabby) is an engineering manager at Arista Networks who will talk your ear off about functional programming if you give her the chance. She is best known for her blog at haskellforall.com and for authoring the Dhall configuration language.

Event details: https://www.meetup.com/Bay-Area-Haskell-Users-Group/events/284148984/

Recording also available on YouTube

Talk by Anthony Sheldon for the Bay Area Haskell Users Group (BAHUG) virtual meetup on May 2, 2020. Meetup link: https://www.meetup.com/Bay-Area-Haskell-Users-Group/events/270204729/

NoRedInk, a San Francisco company that uses Haskell, kindly offered to host this meetup at their office, but due to the COVID-19 pandemic we held this meetup virtually via Zoom. Software Engineer Katie Hughes from NoRedInk joined us to share some details about NoRedInk near the beginning of the video.

Agenda:

Abstract for Anthony's talk:

Library authors are often faced with a design choice: should a function with preconditions be implemented as a partial function, or by returning a failure on incorrect usage? Neither option is ideal. Partial functions lead to frustrating run-time errors. Failure must be checked at the use-site, placing an unfair tax on the users who have ensured that the function’s preconditions were met. What if you could achieve many of the benefits of dependent and refinement types, whilst only requiring some minor and well understood extensions to haskell2010? TL;DR: You can use the same rank-2 types trick used in the ST monad to get the compiler to check a surprisingly wide range of API invariants and preconditions.

Slides: https://slides.com/anthony-1/deck-1c0c6a

Also available on YouTube: https://youtu.be/AaQtAAC29Es

Talk by Chris McKinlay of Formation for the Bay Area Haskell Users Group (BAHUG), December 11 2018.

In this talk, Chris goes through some battle hardened design patterns for working with multiple ML frameworks in a seamless and simple manner.

Also available on YouTube: https://youtu.be/DmR6lvCSn3E

Talk by Stephan Boyer at the Bay Area Haskell Users Group (BAHUG) meetup at Formation, December 11 2018.

Have you ever wanted to formally prove an algorithm correct or a theorem true? This talk will show you how! We'll cover the fundamentals of computer-assisted theorem proving using Coq, one of the most popular proof assistants. Coq is a functional programming language whose type system can encode essentially any mathematical proposition.

Most introductions to Coq survey the landscape from a bird's eye view. You start by building proof scripts using high-level "tactics", and later you're introduced to the actual proofs generated by these tactics. For some, this is a bit too magical. You learn to prove simple theorems, but lack intuition for what the tactics are actually doing. That conundrum was frustrating for me when I was learning Coq in graduate school. This talk, in contrast, will feature no magic.

Instead, we will approach Coq from the perspective of a functional programmer. We'll start with the syntax, which will be familiar to Haskell programmers. We'll learn how to encode propositional logic in data types, which can be done in any functional language. Then we'll see how to encode quantifiers using dependent types, which completes the foundation of higher-order logic. Finally, we'll learn how to automate our proofs using Coq's tactic language. The more you automate, the shorter and more robust your proofs become!

Also available on YouTube: https://youtu.be/bCxqtD-jH48

Max Tagher gave a talk at the August 2018 Bay Area Haskell Users Group meeting on Cryptonite, a repository on cryptographic primitives such as ciphers, hash functions, and more.

Demo Source Code: https://github.com/MaxGabriel/cryptonite-talk/tree/master/demos

Also available on YouTube: https://youtu.be/nsYwcjpYYFE

Mark Fine gives a talk at the Bay Area Haskell Users Group about discussing how to use the Shake build system as a replacement for make files.

Also available on YouTube: https://youtu.be/A1WE0E1gVbQ

Conor McBride gives a talk at the Bay Area Haskell Users Group about writing containers in Haskell. A container is a functor with a "shapes and positions" presentation: the contained values are given as the image of a function from positions, but the type of positions depends on the value of the shape. Some container theory will be live-coded using many GHC language extensions.

Conor has a post on his blog about this topic as well: https://pigworker.wordpress.com/2015/06/06/hasochistic-containers-a-first-attempt/

Also available on YouTube: https://youtu.be/dGv9zJfTf58