> Haskell + Nix is the best environment I've ever used for any development

That sounds like a recommendation.

That's because it's spefically optimized for my needs: writing Reflex apps. It's what I do for a living.

Everyone has different priorities. I know some users who started using Haskell at all with reflex-platform despite the difficulty because it scratched exactly their itch.

Well, as complex as Nix+whatever-you-have-cobbled-together-to-build-and-editor-instrument-ghcjs is, it pales in comparison to the sheer ferocious confusion granted to the ecosystem by tools like webpack, so I can see where it might seem like an improvement in some regards.

Webpack: it's like lens error messages for your builds, at runtime!

for developing haskell

It sure read like that to me, but given the international nature of this forum, I'll take you at your word. Nor do I disagree with you about your assessment of your experience.

But your experience and your requirements differ from mine, and in a professional capacity I could never recommend Nix for an organization.