I’ve recently started looking at Fable as way to use F# to write Web Apps.

For the past 2 years I have had a game that I wrote in TypeScript as a playground for learning more about the language. However, not been a JavaScript or a game developer I think I had some fundamental problems with the app that I never managed to escape.

Over the past few months Fable has kept appearing on my twitter stream and looked really interesting, especially as it can create React Web Apps, which is something I need to know more about.

I began by using the SAFE-Dojo from CompositionalIT as a playground to learn and found it did a real good job of introducing the different parts of the SAFE-Stack.

Using it as a reference, I managed to re-write my game in Fable in very little time.

If you want to see it in action you can have a look here. It’s quite basic and doesn’t push the boundaries in away, but it’s inspired by my Daughter, and she loves to help me add features.

Why do I love SAFE?

There are a number of awesome features of this whole stack that I want to shout about:

Less Bugs

With the old version, I found managing state really hard, there was a persistent bug where the user could click “hit” twice on the same monster and get double points.

With Fable and Elmish, you have a really great way of managing state. Yes, it is another model-view-everything else approach. But the idea of the immutable state coming in and new state been returned is a great fit for functional programming.

You are also coding in F# which can model Domains really well meaning you are less likely to have bugs.

Less Code

I’m always surprised by how small each commit is. I might spend 30 minutes or more messing with a feature, but when I come to commit it, it’s only ever a few lines of code. Even replacing the timer for the entire game was a small change.

Fulma, or should I say Bulma

The SAFE Stack introduced me to Fulma which is a set of Fable helpers for using Bulma.

At first I struggled to get to grips with Fulma, but once I realised how it just represented the Bulma stylings, I found it much easier. Even someone as bad at UI as me, can create something that doesn’t look terrible.

I mostly kept the Bulma documentation open when styling the app as it had better examples and I could translate them to Fulma in my head.

It’s React

React is quite a big thing at the moment, and something I’m looking to use at work. Having something that is React, but isn’t pure JS is great for me. It also supports Redux, so things like the Chrome React and Redux developer tools work with it.

These are amazingly useful tools for debugging Web Apps, even ones this simple.

Conclusion

I’m going to keep looking for situations where I can use the SAFE-Stack. Next will have to be something more complicated - with multiple pages and a back-end with some persistence.

This will give me a feel if it could be something I could use everyday - I’d really like to code this way all the time.

I’m already looking to push F# at work, and this would be a great compliment.