SAFE apps with F# web stack

In this entry I describe my talk on creating web apps in F# and SAFE Stack - the motivation behind, as well as format of the talk.


Web development is still getting its momentum. Enormous JavaScript ecosystem gobble next developers - indeed according to StackOverflow 2017 Developer Survey Results, JS is "the most popular technology" (not going into debates on what that actually means).

Meanwhile, more and more compile-to-javascript solutions contribute to the market, including:

  • TypeScript,
  • CoffeeScript,
  • Dart,
  • ...,

and more functional-style languages like:

  • Elm,
  • PureScript,
  • Reason,
  • ...,
  • ... and F#!

Fable - a F# to JavaScript compiler is doing pretty well in convincing web devs to itself. The project has also been a motivation for a movement in F# community to introduce SAFE Stack. Having played with SAFE apps for a while, I decided to create a talk devoted to the topic.

Talk format

What I found appealing in SAFE, was the development experience:

  • Everything is F#, even bindings to Bulma CSS Framework brought by Fulma: type-SAFEty for the win!,
  • I can write "Isomorphic" code to be shared between client and server,
  • Development tools like dotnet watch, webpack, webpack-dev-server, HMR which combined together make it so that you even don't have to worry about recompiling the code! Just resave your sources, and observe the changes in the browser.

That's why I decided to make the talk a live coding session, where I could share with the audience just how easy and joyful it is to work with SAFE Stack in practice.

Because second letter from the SAFE acronym stands for Azure, I thought it'd be nice to actually deploy the final app to the cloud, so that the audience can play with it on their mobile phones.

This is how I decided to create during the demo a simple voting app, so that listeners can score my talk just after I deploy it to Azure.

Lambda Days 2018

I had a pleasure to give the talk at Lambda Days 2018, which turned out to be an awsome conference again - big thanks to the organizers for having me!

lambda days

Fortunately everything went fine, and I managed to deliver the voting app to Azure (though I exceeded time limit a bit - sorry for that!).

As can be seen in the mobile screenshots below, overally audience seemed to enjoy the session (some of them even tried to SQL-inject my in-memory DB 😃):

F# Exchange 2018

fsharp exchange

This year in April, I'm also excited to join F# Exchange as a speaker. I'll give the SAFE talk again, but this time will have to adjust a bit to more F#-oriented audience. Also, SAFE is moving forwards very rapidly, so I might consider showcasing some of the brand new capabilites.

Can't wait to meet everyone from the awesome F# community in London. If you want to see creating SAFE app live in action, then I hope to see you there as well!


  • Slides for the talk are available here,
  • Source code of the final solution from Lambda Days 2018 is on GitHub,
  • Video from Lambda Days is now available here.