The (rnrs records inspection (6))library provides procedures for
inspecting records and their record-type descriptors. These procedures are designed
to allow the writing of portable printers and inspectors.
[R6RS] Returns #t if obj is a record, and its record type is not opaque, and returns #f otherwise.
[R6RS] Returns the rtd representing the type of record if the type
is not opaque. The rtd of the most precise type is returned; that is, the type
t such that record is of type t but not of any type that
extends t. If the type is opaque, an exception is raised with condition
type &assertion.
[R6RS] Returns the name/parent/uid of the record-type descriptor rtd.
[R6RS] Returns #t if the record-type descriptor is generative/sealed/opaque, and #f if not.
[R6RS] Returns a vector of symbols naming the fields of the type represented
by rtd (not including the fields of parent types) where the fields are
ordered as described under make-record-type-descriptor.
[R6RS] Returns #t if the field specified by k of the type represented
by rtd is mutable, and #f if not. K is as in record-accessor.