Question: I am not looking for a necessarily super-robust solution with a 10-year track record, but for something that can be used in a real applications, and goes beyond just being able to run an Hello World example.

My preference is to run the compiler on the server, so I can compile Haskell code ahead of time. Of course, the solution would need to be more than just a compiler, and enable Haskell code to access the API available on the browser (DOM, XHR…).

Footnote: the projects I have seen so far don't seem to be actively maintained, or to go beyond being able to run "Hello world", or in some case even to go beyond a project description.

Answer: 
There is a more complete list here:

<http://www.haskell.org/haskellwiki/The_JavaScript_Problem>

and there is also Fay (although it is only a subset of haskell)

<https://github.com/faylang/fay>
I have stumbled upon this project called [ghcjs](https://github.com/pedromartins/ghcjs)

It seems promising!

Quote from the `README`:

> 
> Haskell to Javascript translator
> ================================
> 
> 
> Project aims to provide solution to
> 
> 
> * compile modern Haskell libraries to Javascript files and use
>  them in Ajax applications or
> * develop entire Ajax application in Haskell language
> 
> 
> Previous version of project is located at [vir.mskhug.ru](http://vir.mskhug.ru/).
> 
> 
>