The mirrors vocabulary defines data types which present an object's slots and slot values as an associative structure. This enables idioms such as iteration over all slots in a tuple, or editing of tuples, sequences and assocs in a generic fashion. This functionality is used by developer tools and meta-programming utilities.

A mirror provides such a view of a tuple:

<mirror> ( object -- mirror )

Utility word used by developer tools which inspect objects:
make-mirror ( obj -- assoc )

See also
Low-level slot operations