Most of this is sugar, e.g. flat() and flatMap(), out of scope for a language spec. Function.toString being more accurate is helpful. But real progress would

Most of this is sugar, e.g. flat() and flatMap(), out of scope for a language spec. Function.toString being more accurate is helpful. But real progress would be removing dangerous backtracking regular expressions in favor of RE2: https://github.com/google/re2/wiki/Syntax https://github.com/google/re2/wiki/Syntax