It's not rock-solid nor complete.
The authors refused to fix a parser error related to negative literals: https://github.com/elm/compiler/issues/1773
The authors refused to fix a parser error related to negative literals: https://github.com/elm/compiler/issues/1773
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
I don't think the language is complete, but that we should aspire towards completeness over churn.