I'm enjoying the discussion, thanks! Elm really does sound heavily opinionated, but that's often for the better, as you say. How's the tooling, besides the compiler+error messages? I've seen a web-based interactive editor, but I assume that's not _the_ way to write Elm.
The tooling is solid, the lsp server provides auto completions and edit by edit syntax checking in major editors like vim, Emacs and vscode, there is a good formatting tool in elm-format, a built in repl which is basic but works fast. A test runner is also there, with support for fuzzing. Not to mention a time travel debugger which is a highlight.
Things that are missing or not good are proper logging, step by step line debugger, profiling and performance tracking.
