For now, this reference is a best-effort document. We strive for validity and completeness, but are not yet there. In the future, the docs and lang teams will work together to figure out how best to do this. Until then, this is a best-effort attempt. If you find something wrong or missing, file an issue or send in a pull request.


Whitespace is any non-empty string containing only characters that have the Pattern_White_Space Unicode property, namely:

  • U+0009 (horizontal tab, '\t')
  • U+000A (line feed, '\n')
  • U+000B (vertical tab)
  • U+000C (form feed)
  • U+000D (carriage return, '\r')
  • U+0020 (space, ' ')
  • U+0085 (next line)
  • U+200E (left-to-right mark)
  • U+200F (right-to-left mark)
  • U+2028 (line separator)
  • U+2029 (paragraph separator)

Rust is a "free-form" language, meaning that all forms of whitespace serve only to separate tokens in the grammar, and have no semantic significance.

A Rust program has identical meaning if each whitespace element is replaced with any other legal whitespace element, such as a single space character.