Words

Table of contents

Overview

A word is a lexical element formed from a sequence of letters or letter-like characters, such as fn or Foo or Int.

The exact lexical form of words has not yet been settled. However, Carbon will follow lexical conventions for identifiers based on Unicode Annex #31. TODO: Update this once the precise rules are decided; see the Unicode source files proposal.

Carbon source files, including comments and string literals, are required to be in Unicode Normalization Form C (NFC).

Keywords

The following words are interpreted as keywords:

  • abstract
  • adapt
  • addr
  • alias
  • and
  • as
  • auto
  • base
  • break
  • case
  • choice
  • class
  • constraint
  • continue
  • default
  • destructor
  • else
  • export
  • extend
  • final
  • fn
  • for
  • forall
  • friend
  • if
  • impl
  • impls
  • import
  • in
  • interface
  • let
  • library
  • like
  • match
  • namespace
  • not
  • observe
  • or
  • override
  • package
  • partial
  • private
  • protected
  • require
  • return
  • returned
  • Self
  • template
  • then
  • type
  • var
  • virtual
  • where
  • while

Raw identifiers

A raw identifier looks like r#<identifier>. This can be used for identifiers which have the same spelling as keywords; for example, r#impl. It can help when using C++ code with identifiers that are keywords in Carbon.

The identifier doesn’t need to be a keyword, in order to support forwards compatibility when a keyword is planned to be added. When <identifier> is not a keyword, it will refer to the same entity as r#<identifier>.

Alternatives considered

References