Aura

Auras are types of atoms. A generic atom (@) is a non-negative decimal integer. Auras allow such atoms to be defined more specifically, such as @t for little-endian UTF-8 strings, @ux for hexadecimal and @p for a ship name like ~sampel-palnet. Auras do three things:

1. Define type nesting logic, such that @tas nests under @, @t, and @ta but not @p.
2. Let the pretty-printer know how to print the values, so a @t like 'foo' prints as 'foo' rather than 7.303.014.
3. Define literal syntaxes for the various auras, so the parser/compiler can understand them.

Note that auras do not enforce the validity of an encoding scheme, so you can type-cast the @t '!!!' to @ta despite ! not being allowed in an @ta literal. They are ultimately just metadata given to compiler.

Further reading

• Aura reference: Additional information about auras.
• Hoon School: syntax lesson: Includes details of atoms and auras.