record.scm

(import (scheme base)
        (scheme write))

(define-record-type rb-tree
  (%make-rb-tree compare)
  rb-tree?
  (node rb-tree-node set-node!)
  (compare rb-tree-compare set-rb-tree-compare!)
  (size rb-tree-size set-size!))

(define (compare i1 i2)
  (- i1 i2))

(define (make-rb-tree . cmp)
  (let* ((cmp (if (null? cmp) compare (car cmp)))
         (rb (%make-rb-tree cmp)))
    (set-node! rb 'leaf)
    (set-size! rb 0)
    (write (rb-tree-compare rb))        ; #<unbound>になってしまう
    rb))

(make-rb-tree compare)