Keywords

The following words are reserved and cannot be used as ordinary identifiers:

namespace  using      public      internal    private
export     function   local       return      end
const      record     union       class       interface
enum       attribute  type        open        implements
if         then       elseif      else        while
repeat     until      for         do          break
continue   match      when        with        nil
true       false      and         or          not

Reservation does not mean every word introduces every planned form. In rc.3, for implements numeric ranges but not generalized for value in iterable; enum implements nominal payload-free cases; and type implements non-generic erased aliases. open inheritance is not part of the supported executable surface. export is rejected because declarations use public, internal, or private directly.

Built-in type names such as Int, String, and Boolean are language-provided names rather than keywords in the same lexical category.