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# Structures

A structure type is a record datatype composed of a number of named fields. A structure, an instance of a structure type, is a first-class value that contains a value for each field of the structure type. A structure instance is created with a type-specific constructor procedure, and its field values are accessed and changed with type- and field-specific selector and setter procedures. In addition, each structure type has a predicate procedure that answers `#t` for instances of the structure type and `#f` for any other value.

- Creating Structure Types
- Creating Subtypes
- Structure Utilities