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6.2.1.4 Composite Keys
— Operation on base-table: make-keyifier-1 type

Returns a procedure which accepts a single argument which must be of type type. This returned procedure returns an object suitable for being a key argument in the functions whose descriptions follow.

Any 2 arguments of the supported type passed to the returned function which are not equal? must result in returned values which are not equal?.

— Operation on base-table: make-list-keyifier key-dimension types

The list of symbols types must have at least key-dimension elements. Returns a procedure which accepts a list of length key-dimension and whose types must corresopond to the types named by types. This returned procedure combines the elements of its list argument into an object suitable for being a key argument in the functions whose descriptions follow.

Any 2 lists of supported types (which must at least include symbols and non-negative integers) passed to the returned function which are not equal? must result in returned values which are not equal?.

— Operation on base-table: make-key-extractor key-dimension types column-number

Returns a procedure which accepts objects produced by application of the result of (make-list-keyifier key-dimension types). This procedure returns a key which is equal? to the column-numberth element of the list which was passed to create composite-key. The list types must have at least key-dimension elements.

— Operation on base-table: make-key->list key-dimension types

Returns a procedure which accepts objects produced by application of the result of (make-list-keyifier key-dimension types). This procedure returns a list of keys which are elementwise equal? to the list which was passed to create composite-key.