Building a web app with functional programming - Elm - part II


  1. Building a web app with functional programming series :bookmark:
  2. Definition of production ready :bookmark:
  3. Elm - part I :bookmark:
  4. Elm - part II :bookmark:
  5. Haskell - part I :bookmark:
  6. Haskell - part II :bookmark:
  7. Nixos :bookmark:

Time to talk about Elm’s ecosystem ! If you haven’t read it yet, check out part I of Building a web app with functional programming.

Guide, documentations and best practices

It might sounds peculiar to talk about Elm’s guide but it helped me get up to speed in few hours. This is quite a satisfying feeling to be writing real world code after a day or two. Thanks to its well written and beginner friendly guide, understanding how Elm’s architecture works is a painless process.

The very same can be said about its documentation. Official libraries or not, I haven’t found a documentation that was poorly written yet. To be fair, I don’t use many unofficial libraries. But still, I believe writing good documentation is part of Elm’s spirit.

Elm comes with tons of materials to learn from. Some content helped me understand and improve my overall skills. I would particularly recommend watching all of Richard Feldman talks which were all helpful designing better architecture.


Elm has a great community. When I had questions, answers are always helpful. It might not be that surprising but I think it’s a huge deal. Learning from scratch a language that uses FP’s concepts (sum types, pure function, Maybe…) for traditional developers is difficult so having an empathic community helps a lot !


I won’t write much about the tooling as I almost don’t use anything. I write Elm with emacs without any plugins and it feels nice enough. I tried to install elm language server protocol (LSP) on emacs but failed miserably :pensive:. I will probably give it another try later this year but I don’t feel the urge to have IDE features for now. The compiler itself is plenty enough for my needs.


I couldn’t finish this part on Elm without talking about Elm-ui.
I have to admit beforehand that I loathe CSS. Hours of buttons and labels/inputs aligments triggers angers when I hear the CSS word. Even Flexbox and other famous frameworks (bootstrap and whatnot) could not completely ease the pain.
So when I had to start writing CSS again, I could feel the frustration rushing back.

Then, some day, I stumbled on elm-ui, a library designed to replace CSS. I gave it a try and quickly adopted it.
With Elm-ui, you won’t have to write css ever again. You directly integrate the element properties (shape, alignment, color…) within your business code.

Initially I thought that not splitting the presentation, decoration from the business layer would be a terrible idea but so far I haven’t found any downsides and it integrates nicely with my project without any maintainability costs.
Elm-ui saved me hundreds of hours of frustration, helped me design a nice UI (not mobile friendly in complete honesty) and made UI development fun again.


The downsides

There are many fields I haven’t experimented yet. Javascript interaction with Ports, mobile UI/UX design, more advanced UI like modals, animations… So I don’t have the full picture of the language. But from my experience, it’s hard to give any impactful downsides. After months of development, I have yet to find something that felt inherently bad or could be improved.
Sure it will feel a bit verbose for Haskellers and some concepts are hard to initially grasp for beginners (json encoder/decoder, url parsing, maybe) but that’s hardly an inconvenience compared to the gain in productivity.

I will keep on writing elm and maybe I’ll find downsides. In the meantime, give it a try, you won’t be disappointed!

Production ready?

So is it production ready ? :100:% yes. The learning curve is quite shallow so your team will get up to speed in a matter of days. The benefits are huge:

If it fits your need you should totally embrace Elm.

Delightful language?

Because of its friendly community, its well written guides/documentation, its beginner focused approach and its fast and helpful compiler, Elm has become my go to language for front end application.

It is such a great product that I also advise people who want to learn about functional programming to avoid Scala or Haskell and learn Elm instead. In my opinion, Elm does a fabulous job at discovering the advantages of functional programming over more traditional paradigms.

So yeah, it doesn’t come as a surprise that I find Elm a delightful language :heart: