Building Web Apps with OCaml/Reason

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OCaml is gaining traction as a language of choice for building web applications, a trend largely driven by the ReasonML ecosystem. We have organized an extended event with 3 great talks. Come learn about the wide range of OCaml/Reason technologies that together promise to change the way you think about web apps, and native apps too.

This is our biggest event ever. Don’t miss it! RSVP here on

Many thanks to our sponsor Jane Street for providing food and drinks, and a beautiful venue.


5:30 - 5:45pm
Food & Networking

5:45 - 6:30pm
Talk 1: Data Driven UIs, Incrementally
Speaker: Yaron Minsky (Jane Street)

A difficult problem at the heart of trading applications is to filter, transform, and present data in a way that is simultaneously easy to understand and efficient. This talk will show how we approached this problem using Incremental, an OCaml library for constructing dynamic computations that update efficiently in response to changing data. We'll show how Incremental can be used throughout the application, from the servers providing the data to be visualized, to the JavaScript code that generates DOM nodes in the browser. This has also driven us to develop efficiently diffable data structures to bridge the worlds of functional and incremental computing.

Yaron got his BA in Mathematics from Princeton and his PhD in Computer Science from Cornell, where he studied distributed systems. He joined Jane Street in 2003, where founded the firm's quantitative research group. He introduced OCaml to the company and managed the transition to using OCaml for all of its core infrastructure, turning Jane Street into the world's largest industrial user of the language. In the meantime, he's been involved in many different aspects of Jane Street's technology stack, including trading and risk systems, developer tools, and user-interface toolkits. Yaron has lectured, blogged and written about programming for years, with articles published in Communications of the ACM and the Journal of Functional Programming, and is co-author of the book Real World OCaml.

Break: 5 minutes

6:35 - 7:20pm
Talk 2: React Hooks in Reason
Speakers: Ricky Vetter, Cristiano Calcagno (Facebook)

Hooks are a new concept introduced to React that allow function components to be stateful. The API opens up some new opportunities for those writing their applications in Reason. This talk will go into how hooks work, what new things you can do with them, and some examples of how to use them.

Ricky has been working as a Front End Engineer at Facebook since 2015. As one of the original adopters of Reason on the Messenger Web project, he has worked with the Reason core team and contributes to ReasonReact.

Cristiano is a software engineer at Facebook. His goal is to build tools that enable the rapid development of reliable software. He and his co-authors were recipients of the ACM SIGPLAN Most Influential POPL Paper Award for 2019, awarded for their work on the Infer tool.

Break: 10 minutes

7:30 - 8:15pm
Talk 3: Reason and React Native: A Perfect Match
Speaker: Ken Wheeler (Citadel Securities)

This talk will explore writing React Native apps with ReasonML, the bs-react-native bindings, and why you should give it a try for your next app. I'll make the case that native apps have an inherent higher level of quality expectation, and that meeting that expectation requires a higher degree of certainty, along with nice to have like enum based types, styles, etc.

Ken is a developer with a decade of experience in web and mobile technologies. He specializes in JavaScript, and specifically React. More recently he has been working with ReasonML. He is a very active member of the open source community. He primarily writes code, but also has experience in client relations, communication, management, and evangelism.

8:30pm - ??
Afterwards, we’ll head down to P.J. Clarke’s to continue the conversation.