- Poor ecosystem fit for an enterprise environment. We weren't willing to write libraries for some of the things we needed to support: DB2 access, SOAP, etc. Ended up writing C# wrapper services for a lot of that early on
- Poor library ecosystem in some cases. What felt like a good choice would be unsupported a year later
- Perhaps our own fault for committing to using Reflex for a heavyweight frontend. The team did an amazing job, but supporting GHCJS, the tooling around it, and trying to get faster dev iterations became a huge drag on the team
- Indirectly had to support it due to Reflex, but Nix. It's another rabbit hole that requires collective interest and a willingness to peel back the layers to make things work. Was another drag on the team
At the end of the day I'd say the biggest problem was cultural. I firmly believe that in order to have a successful Haskell environment, you need devs committed to the language and would label themselves "Haskellers". My team learned it and became expert engineers, but they are by no means Haskell language pros who thoroughly understand the inside outs of the language and its myriad of extensions. It's just a tool to them and they only used as much as they needed to.