* Added a comment file about r6rs records.

This commit is contained in:
Abdulaziz Ghuloum 2007-05-14 14:53:29 -04:00
parent 94ff7fcc6e
commit e831d54afe
1 changed files with 51 additions and 0 deletions

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src/r6rs-records.ss Normal file
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;;; procedural layer:
(make-record-type-descriptor name parent uid sealed? opaque? fields)
;;; name is a symbol, for informational purposes only
;;; parent is #f or an rtd
;;; uid is #f or symbol.
;;; symbol => nongenerative (or interned by that name)
;;; #f => generative (can use a gensym for uid)
;;; if parent is sealed?, then it cannot be extended,
;;; therefore, parent must not be sealed.
;;; if parent is opaque, then so is the rtd (overrides opaque?)
;;; if parent is not opaque, then use opaque?
;;; fields is a vector where each element is either:
;;; (mutable <symbol>) or (immutable <symbol>)
;;; symbols need not be unique, they're informational.
(record-type-descriptor? x)
;;; self explanatory.
(make-record-constructor-descriptor
rtd parent-constructor-descriptor protocol)
;;; returns a record constructor descriptor
;;; protocol is either a procedure or #f
;;; if rtd has no parent, then protocol must be #f
;;; typical protocol procedure is:
;;; (lambda (new)
;;; (lambda (bar baz) ;;; constructor of 2 args
;;; ;;; for a record of three fields
;;; (new bar baz (* bar baz))))
;;; default protocol procedure is (lambda (new) new)
;;; an extension protocol is typically:
;;; (lambda (parent-new)
;;; (lambda (px py pz x y z)
;;; (let ([new (parent-new px py pz)])
;;; (new x y z))))
;;; or (lambda (parent-new)
;;; (lambda (px py pz x y z)
;;; ((parent-new px py pz) x y z)))
;;;
(record-constructor rcd)
;;; returns a procedure that constructs records. The number of
;;; arguments that the procedure takes is the same number of
;;; arguments in the protocol's inner lambda.
(record-predicate rtd) ;=> predicate procedure.
(record-accessor rtd k) ;=> accessor procedure.
(record-mutator rtd k) ;=> mutator procedure.