I've done the Glasgow Haskell course. It's hard. Some of the hardness was being 10hrs out of sync with the rest of the class who were in the UK and I wasn't but it's also hard because changing from 30+ years of imperative thinking to functional thinking is hard. Some people say it takes 6 weeks to break a habit, well the course lasted about 8 weeks and I didn't break the habit.<p>Of course you <i>can</i> code in the imperative mode in an FP and in fact, some people do teach this for the benefit of having strongly typed, and functional language inside the model. If you learn the type model and the REPL then the rest can follow naturally.<p>My employer had one or two webapps written in elm and they worked well. The stakeholder hated the L&F so as usual, they died on issues tangential to the coding language but there was a valid point made by other coders: If you go this far off the common path, you make support burdens for other people. I think this is part of why FP for web is so thin on the ground: it requires substantial cross group participation to succeed at scale, a lone-wolf won't get you a good outcome