Something I've just found is that the errors can also be output in a nice machine readable format, so the suggested fixes can be read in by your editor plugin.
And finally, this is wonderful, a specific repo for code that causes error messages and a request for people to submit error messages that are confusing: https://github.com/elm-lang/error-message-catalog
If you're interested, there were a couple more examples shown elsewhere in this thread:
http://elm-lang.org/blog/compiler-errors-for-humans (an older version it seems)
https://twitter.com/st58/status/732908457217531904
https://twitter.com/GregorySchier/status/732830868562182144
Something I've just found is that the errors can also be output in a nice machine readable format, so the suggested fixes can be read in by your editor plugin.
And finally, this is wonderful, a specific repo for code that causes error messages and a request for people to submit error messages that are confusing: https://github.com/elm-lang/error-message-catalog